X-Ray safety cover.pgm - My Illinois Statemy.ilstu.edu/~gferren/CHE38045gf/materials/X-Ray and...

Self-Study

X-Ray Safetyfor Analytical and Industrial Settings

LEAD

LosN A T I O N A L L A B O R A T O R Y

Alamos

X-RAY COMPLIANCE LABEL

PN:___________________________

Resurvey Due:_________________ ______________ Month Year

_____________________________ ______________X-Ray Device Control Office Rep. Date

This machine has been surveyed and found tomeet applicable radiation safety standards

and operational safety requirements.

LA-UR-99-5083

This training course is presented with the understanding that the information and materialsprovided were developed based on specific circumstances present at the Los Alamos NationalLaboratory at the time of publication. Those circumstances may or may not be similar toconditions present at other locations represented by participants in this course. Thecourse materials and information will need to be adapted accordingly. The University ofCalifornia/Los Alamos National Laboratory will not be liable for direct or indirect damagesresulting from use of this material.

Instructional DesignersAnn Anthony

Mike McNaughtonTechnical Advisor

David LeeEditors

Denise Derkacs and Karen SmithIllustrators

Jim Mahan and Tamara TuckerCover Designer

Rosalie Ott

Course Number: 12326 December 1998

Document Number: ESH13-335-ks-12/98

Contents

X-Ray Safety for Analytical and Industrial Settings i

Introduction ............................................................................... 1

Course Purpose ....................................................................... 1

Course Objectives.................................................................... 1

Regulations and Guidance ....................................................... 2

ANSI Objectives ....................................................................... 3

About this Self-Study Guide...................................................... 3

Unit 1: Radiation Protection Principles................................... 5

Unit Objectives ......................................................................... 5

Atoms and Ions ........................................................................ 5

Radiation .................................................................................. 6

Units of Measure ...................................................................... 7

Background Radiation .............................................................. 7

Dose Limits and Control Levels................................................ 8

Causes of Accidental Exposures.............................................. 9

ALARA ..................................................................................... 9

Self-Assessment ...................................................................... 11

Answers ................................................................................... 14

Unit 2: Production of X-Rays ................................................... 15

Unit Objectives ......................................................................... 15

Electromagnetic Radiation ....................................................... 16

X-Ray Production ..................................................................... 17

Photon Energy and Total Power .............................................. 19

Interaction with Matter .............................................................. 20

Implications of Photon Energy and Total Power....................... 21

Self-Assessment ...................................................................... 22

Answers ................................................................................... 25

☞

Contents

ii X-Ray Safety for Analytical and Industrial Settings

Unit 3: Biological Effects.......................................................... 27

Unit Objectives ......................................................................... 27

Early History of X-Rays ............................................................ 28

Biological Effects of Radiation.................................................. 30

Factors that Determine Biological Effects................................. 31

Somatic Effects ........................................................................ 33

Heritable Effects....................................................................... 37

Self-Assessment ...................................................................... 38

Answers ................................................................................... 40

Unit 4: Radiation Detection ...................................................... 41

Unit Objectives ......................................................................... 41

Radiation Surveys .................................................................... 42

Radiation Monitoring Instruments............................................. 42

Personnel Monitoring Devices.................................................. 44

Self-Assessment ...................................................................... 46

Answers ................................................................................... 48

Unit 5: Protective Measures ..................................................... 49

Unit Objectives ......................................................................... 49

Radiological Postings ............................................................... 50

Labels....................................................................................... 52

Warning Devices ...................................................................... 52

Shielding .................................................................................. 53

Work Documents...................................................................... 55

Self-Assessment ...................................................................... 57

Answers ................................................................................... 59

Unit 6: X-Ray Generating Devices ........................................... 61

Unit Objectives ......................................................................... 61

Intentional and Incidental Devices............................................ 62

Incidental X-Ray Devices ......................................................... 63

Intentional Analytical X-Ray Devices........................................ 63

Intentional Industrial X-Ray Devices......................................... 65

Summary of X-Ray Devices ..................................................... 68

Self-Assessment ...................................................................... 69

Answers ................................................................................... 71

Contents

X-Ray Safety for Analytical and Industrial Settings iii

Unit 7: Responsibilities for X-Ray Safety................................ 73

Unit Objectives ......................................................................... 73

Responsibilities ........................................................................ 74

Self-Assessment ...................................................................... 76

Answers ................................................................................... 78

Lessons Learned....................................................................... 79

Scenario ................................................................................... 79

Lessons Learned...................................................................... 80

References............................................................................... 81

Glossary..................................................................................... 83

Appendix A ................................................................................ 97

Radiation Safety Requirements for Industrial X-Ray Devices .. 97

Appendix B ................................................................................ 103

Radiation Safety Requirements for Analytical X-Ray Devices.. 103

Mail-In Package ......................................................................... 107

Course Credit ........................................................................... 107

Quiz.......................................................................................... 108

Course Roster .......................................................................... 113

Course Evaluation.................................................................... 115

Contents

iv X-Ray Safety for Analytical and Industrial Settings

Notes . . .

Introduction

X-Ray Safety for Analytical and Industrial Settings 1

Course Purpose

The purpose of this course is to increase your knowledge to enableyou to perform your job safely by adhering to proper radiationprotection practices while working with or around x-ray-generatingdevices. This course will inform you about the policies andprocedures you should follow to reduce the risk of exposure to theionizing radiation produced by x-ray-generating devices.

Other hazards associated with the use of some x-ray machinessuch as electrical, mechanical, laser light, and explosives are notaddressed in this course because they are specific to particularmachines and procedures. Neither does this course addressoperating procedures for specific installations. You will receivetraining on the specific operating procedures at your work site.

Course Objectives

Upon completion of this course, you will be able to understand

¥ what x-rays are and how they are generated;

¥ the biological effects of x-rays;

¥ how x-rays are detected;

¥ the measures that protect you from x-rays;

¥ the regulations and requirements governing x-ray devices; and

¥ the responsibilities of the X-Ray Device Control Office,operating groups, x-ray-device custodians, and x-ray-deviceoperators.

☞

Introduction

2 X-Ray Safety for Analytical and Industrial Settings

Regulations and Guidance

The prime compliance document for occupational radiationprotection at Department of Energy (DOE) sites is Title 10 of theCode of Federal Regulations, 10 CFR 835. The DOE RadiologicalControl (RadCon) Manual provides detailed guidance on the bestpractices currently available in the area of radiological control.At Los Alamos National Laboratory (LANL), 10 CFR 835 drives theRadiation Protection Program (RPP).

The American National Standards Institute (ANSI) details safetyguidelines for x-ray devices in two standards, one on analytical(x-ray diffraction and fluorescence) x-ray equipment and anotheron industrial (nonmedical) x-ray installations. Guidance for x-raytraining is also provided by the Nuclear Regulatory Commissionin 10 CFR 19.12 and 10 CFR 34.31.

At LANL, the protection program for individuals working with oraround x-ray devices is implemented through the followingdocuments:

¥ the Laboratory Standard, (LS)107-03.0, X-Ray-GeneratingDevices;

¥ ANSI N43.2 (R1989), Radiation Safety for X-Ray Diffraction andFluorescence Analysis Equipment; and

¥ ANSI N43.3 (1993), American National Standard for GeneralRadiation Safety—Installations Using Non-Medical X-Ray andSealed Gamma-Ray Sources, Energies up to 10 MeV.

Most of the information presented in this course is based on theradiation safety guidelines on x-ray devices contained in ANSIN43.2 and N43.3 and in LS107-03.0, Appendix A, which outlinesthe safety requirements for the design, installation, and operationof industrial x-ray installations, and Appendix B, which outlines thesafety requirements for analytical x-ray diffraction and fluorescenceequipment.

Introduction


ANSI Objectives

The main objectives of ANSI N43.2 and ANSI N43.3 are to keepworker exposure to ionizing radiation at levels that are as low asreasonably achievable (ALARA) and to ensure that no workerreceives greater than the maximum permissible dose equivalent.These objectives may be achieved through the following methods:

¥ using firm management controls,

¥ using standard operating procedures (SOPs) and radiologicalwork permits (RWPs),

¥ maintaining equipment appropriately,

¥ employing a comprehensive maintenance and surveillanceprogram,

¥ using adequate shielding,

¥ maximizing distance from the source, and

¥ minimizing worker exposure.

About this Self-Study Guide

In this Guide

This self-study guide contains seven learning modules, followed bylessons learned, a glossary, and references. The learning modulescontain self-assessments to review the material covered.

At the end of this study guide is a cumulative quiz to review theinformation in all six learning modules. A score of 80% on the quizis required for course credit.

The Mail-In Package at the end of this guide contains instructionson how to receive credit for this course.

Introduction


Notes . . .

Unit 1: Radiation Protection Principles


Unit Objectives

Major Objective

Upon completion of this unit, you will understand basic radiationprotection principles essential to the safe operation of x-raydevices.

Enabling Objectives (EOs)

Using the self-assessment, you will be able to identify

EO1 the structure of atoms and ions,

EO2 the definition of ionizing radiation,

EO3 sources of natural and manmade background radiation,

EO4 DOE and LANL dose limits,

EO5 the ALARA policy, and

EO6 three basic methods for reducing external exposure.

Atoms and Ions

The atom, the basic unit of matter, is made up of three primaryparticles: protons, neutrons, and electrons. Protons and neutronsare found in the nucleus of the atom; electrons are found orbitingthe nucleus. Protons have a positive charge; neutrons are neutral;electrons have a negative charge. Electrons determine how theatom chemically interacts with other atoms to form molecules.

An atom usually has a number of electrons equal to the numberof protons in its nucleus so that the atom is electrically neutral.A charged atom, called an ion, can have a positive or negativecharge, depending on the number of protons and electrons. An ionis formed when an incoming electromagnetic wave or an incomingparticle interacts with an orbiting electron and causes it to beejected from its orbit, a process called ionization.



Radiation

For radiation protection purposes, ionization is important because itaffects chemical and biological processes and allows the detectionof radiation.

Radiation is the transfer of energy through open space. Radiationwith enough energy to cause ionization is referred to as ionizingradiation. Radiation that lacks the energy to cause ionization isreferred to as nonionizing radiation.

Ionizing radiation takes the form of alpha, beta, or neutron particlesor gamma or x-ray photons.

AlphaParticle

NeutronParticle

BetaParticle

γ GammaRay

X-Ray

Figure 1. Ionizing Radiation

X-rays are a form of electromagnetic radiation and are very similarto gamma rays. They differ in their point of origin. Gamma raysoriginate from within the atomic nucleus, whereas x-rays originatefrom the electrons outside the nucleus. X-rays and gamma rays arecommonly grouped together as one type of radiation. This coursewill discuss in detail how x-rays are produced in Unit 2.



Units of Measure

Ionizing radiation is measured in the following units:

¥ roentgen (R), the measure of exposure to radiation, defined bythe ionization caused by x-rays in air;

¥ rad, the radiation absorbed dose or energy absorbed per unitmass; and

¥ rem, the roentgen equivalent man or dose equivalent.

For x-rays, assume that 1 R = 1 rad = 1 rem.

Note: For a more detailed discussion of R, rad, and rem, refer tounit 4 in Accelerator Safety (Self-Study) and in Sealed SourceSafety (Self -Study).

Background Radiation

Background radiation, to which everyone is exposed, comes fromboth natural and manmade sources. The most common sources ofnatural background radiation are cosmic, terrestrial, internal, andradon. The most common sources of manmade backgroundradiation are medical procedures and consumer products.

The average background dose to the general population from bothnatural and manmade sources is about 360 mrem per year. InLos Alamos, background dose averages about 400 mrem per yearbecause of higher altitude and radon levels.

Natural Sources

Manmade Sources

Radon 200 mrem

Cosmic 28 mrem

Terrestrial 28 mrem Internal

40 mrem

Medical X-Rays 39 mrem

Nuclear Medicine 14 mrem

Consumer Products 10 mrem

Other 2 mrem

Figure 2. Average Annual Background Dose



Background Radiation—continued

Naturally occurring sources include an average of about 200 mremper year from radon and its decay products, about 40 mrem peryear from internal emitters such as potassium-40, about 28 mremper year from cosmic rays, and about 28 mrem per year fromterrestrial sources such as naturally occurring uranium and thorium.

Manmade sources include an average of about 10 mrem per yearfrom consumer products such as building materials and about53 mrem per year from medical procedures such as x-rays. Notethat the dose from a chest x-ray is 5 to 10 mrem, from a dental x-ray is 50 to 300 mrem, and from a mammogram is 0.5 to 2 rem.Because these doses are to only parts of the body, the effectivedose equivalent to the whole body is a fraction of these values.

Dose Limits and Control Levels

Limits on occupational doses are based on data on the biologicaleffects of exposure to ionizing radiation and guidance from theInternational Commission on Radiological Protection, the NationalCouncil on Radiation Protection, and the Environmental ProtectionAgency. The limits are well below the doses at which anysymptoms of biological effects appear.

The following table lists DOE dose limits for occupational doses.

DOE Dose Limits

Part of the Body Dose Limits (in rem)

whole body 5 rem/year

extremity 50 rem/year

skin 50 rem/year

internal organ 50 rem/year

Lens of the eye 15 rem/year

embryo/fetus 0.5 rem/term of pregnancy

minors and the public 0.1 rem/year



Dose Limits and Control Levels—continued

DOE facilities are designed and operated to reduce workers’ doseequivalents as far below the occupational limits as reasonable. AtLANL, your lifetime dose in rem is not allowed to exceed your agein years. For example, a 40-year-old worker is limited to a totaldose of 40 rem. The dose equivalent for x-ray workers is typicallybetween 0 and 100 mrem per year above natural background.

Causes of Accidental Exposures

Although most x-ray workers do not receive any measurableradiation above background, accidents related to x-ray-deviceshave occurred when proper work procedures have not beenfollowed. Failure to follow proper procedures has been the result of

¥ rushing to complete a job,

¥ fatigue,

¥ illness,

¥ personal problems,

¥ lack of communication, or

¥ complacency.

Every year about one x-ray incident per hundred x-ray units occursnationwide. Of these incidents, about one-third result in injury to aperson. The accident rate at DOE laboratories is lower than thenational average.

ALARA

Because the effects of chronic exposure to low levels of ionizingradiation are not precisely known, there is an assumed risk fromany exposure. ALARA policy is to keep radiation dose as low asreasonably achievable, considering economic and socialconstraints.

The goal of the ALARA program is to keep radiation dose ALARA,that is, as far below the occupational dose limits and administrativecontrol levels as is reasonably achievable so that there is noradiation exposure without commensurate benefit based on soundeconomic principles. The success of the ALARA program is directlylinked to a clear understanding and following of the policies andprocedures for the protection of workers. Keeping radiation doseequivalent ALARA is the responsibility of each worker.



ALARA—continued

Reducing External Exposure

Three basic ways to reduce external exposure to radiation are to

¥ minimize time,

¥ maximize distance, and

¥ use shielding.

3

MinimizeTime

MaximizeDistance

UseShielding

12

6

9 3

12

6

9 3

In Out

Figure 3. Methods for Reducing External Exposure

Minimize time near a source of radiation by planning ahead.Maximize distance by moving away from the source of radiationwhenever possible. Exposure from x-ray sources is inverselyproportional to the square of the distance (inverse-square law),that is, when the distance is doubled, the exposure is reducedby one-fourth. Use shielding appropriate for the type of radiation.Lead, concrete, and steel are effective in shielding against x-rays.



Self-Assessment

1. Ionizing radiation can remove electrons from a neutral atom toform (EO1)

a. neutrons

b. protons

c. electrons

d. ions

2. Radiation is (EO2)

a. radioactive decay of electrons

b. neutral atoms in a material

c. energy transferred through space

d. neutral ions in an unwanted place

3. All but one of the following are examples of ionizing radiation,except (EO2)

a. alpha

b. beta

c. atom

d. x-ray

4. Radiation to which everyone is exposed to is called (EO3)

a. alpha

b. background

c. cathode ray

d. occupational

5. Background radiation averages about (EO3)

a. 360 mrem per hour

b. 360 mrem per year

c. 360 rem per hour

d. 360 rem per year

6. The DOE dose limit for the whole body is (EO4)

a. 5 mrem per hour

b. 5 rem per hour

c. 5 mrem per year

d. 5 rem per year

✓



Self-Assessment—continued

7. At LANL a 50-year-old worker is limited to an accumulatedlifetime dose of (EO4)

a. 5 rem

b. 20 rem

c. 40 rem

d. 50 rem

8. The dose limit for an embryo or fetus is (EO4)

a. the same as for the whole body of an adult

b. more than for the whole body of an adult

c. less than for the whole body of an adult

d. not specified

9. The policy of keeping radiation dose ALARA is followedbecause the effects of low levels of radiation are (EO5)

a. not precisely known

b. nonexistent

c. unacceptably hazardous

d. as large as regulations allow

10. One of the methods of reducing exposure to radiation is tominimize (EO6)

a. distance

b. time

c. shielding

d. speed

11. If you move away from a point source of x-rays until you arefour times as far away, your exposure will be (EO6)

a. the same

b. one-half

c. one-fourth

d. one-sixteenth

✓



Notes . . .



Answers

1. d

2. c

3. c

4. b

5. b

6. d

7. d

8. c

9. a

10. b

11. d

Unit 2: Production of X-Rays


Unit Objectives

Major Objective

Upon completion of this unit, you will understand what x-rays areand how they are produced so that you will be able to work aroundthem safely.



EO1 the types of electromagnetic radiation;

EO2 the difference between x-rays and gamma rays;

EO3 how x-rays are produced;

EO4 bremsstrahlung and characteristic x-rays;

EO5 the difference between photon energy and total power;

EO6 the effects of voltage, current, and filtration on x-rays;

EO7 how x-rays interact with matter; and

EO8 how energy relates to radiation dose.



Electromagnetic Radiation

X-rays are a type of electromagnetic radiation. Other types ofelectromagnetic radiation are radio waves, microwaves, infrared,light, ultraviolet, and gamma rays. The types of radiation aredistinguished by the amount of energy carried by the individualphotons.

All electromagnetic radiation consists of photons, which areindividual packets of energy. One is not usually aware of theseindividual packets because they are so numerous. For example,a household light bulb emits about 1021 photons per second.

The energy carried by individual photons, which is measured inelectron volts (eV), is related to the frequency of the radiation.Different types of electromagnetic radiation and their typical photonenergy are listed in the following table.

Electromagnetic Radiation

Type of Radiation Typical Photon Energy

radio wave 1 µeV

microwave 1 meV

infrared 1 eV

red light 2 eV

violet light 3 eV

ultraviolet 4 eV

x-ray 100 keV

gamma ray 1 MeV



Electromagnetic Radiation—continued

X-Rays and Gamma Rays

X-rays are similar to gamma rays in their ability to ionize atoms.Other types of electromagnetic radiation are nonionizing. It takes5 eV of photon energy to ionize a carbon atom, so one x-ray photon(typically 100 keV) can ionize thousands of atoms.

As discussed in Unit 1, the distinction between x-rays and gammarays is their origin, or method of production. Gamma rays originatefrom within the nucleus; x-rays originate from the electrons outsidethe nucleus.

In addition, gamma photons often have more energy than x-rayphotons. For example, diagnostic x-rays are about 40 keV, whereasgammas from cobalt-60 are about 1 MeV. However, there are manyexceptions. At LANL for example, gammas from plutonium areless than 60 keV, whereas x-rays from the pulsed high-energyradiographic machine emitting x-rays (PHERMEX) are about10 MeV.

X-Ray Production

X-rays are produced when charged particles, usually electrons,are accelerated by an electrical voltage (potential difference).Whenever a high voltage, a vacuum, and a source of electrons arepresent in any scientific device, x-rays can be produced. This iswhy many devices that use high voltages produce incidental x-rays.Televisions, computer monitors, and many other devices at LANLproduce incidental x-rays.



X-Ray Production—continued

Most x-ray devices emit electrons from a cathode, accelerate themwith a voltage, and allow them to hit an anode, which emits x-rayphotons.

+

Copper Anode

TungstenTarget

Electrons

Heated Tungsten Filament

EvacuatedEnvelope

Figure 4. X-Ray Tube

Bremsstrahlung

When electrons hit the anode, they decelerate or brake,emitting bremsstrahlung (meaning braking radiation in German).Bremsstrahlung is produced most effectively when small chargedparticles hit large atoms such as when electrons hit a tungstenanode. However, bremsstrahlung can be produced with anycharged particles and any target. For example, at researchlaboratories such as LANL, bremsstrahlung has been producedby accelerating protons and allowing them to hit hydrogen.

Characteristic X-Rays

When electrons change from one atomic orbit to another,characteristic x-rays are produced. The individual photon energiesare characteristic of the type of atom and can be used to identifyvery small quantities of a particular element. For this reasonthey are important in analytical x-ray applications at researchlaboratories such as LANL.



Photon Energy and Total Power

For radiation protection purposes, it is important to distinguishbetween the energy of individual photons in an x-ray beam and thetotal energy of all the photons in the beam. It is also important todistinguish between average power and peak power in a pulsedx-ray device.

Typically, the individual photon energy is given in electron volts(eV), whereas the total power of a beam is given in watts (W).Consider an analogous example from visible light: a 100-W red lightemits more total power than a 10-W blue light; however, blue lightphotons have more energy than red light photons.

The photon energy may be varied either by changing the voltage orby using filters that are analogous to the colored filters used in light.The number of photons emitted may be varied by changing thecurrent.

Voltage

The photon energy produced by an x-ray device depends on thevoltage, which is measured in volts (V). A voltage of 10 kV willproduce up to 10-keV x-ray photons. Most of the x-ray photonsproduced by a given maximum electron acceleration potential willbe approximately one-third of the maximum electron accelerationpotential. For example, a 120-kV-peak (kVp) diagnostic x-raymachine produces x-ray photons most of which will have energiesaround 40 keV. Many x-ray devices have meters to measurevoltage. Whenever the voltage is on, a device can produce x-rays,even if the current is too low to read.CurrentThe total number of photons produced by an x-ray device dependson the current, which is measured in amperes, or amps, (A). Thecurrent is controlled by increasing or decreasing the number ofelectrons emitted from the cathode. The higher the electron current,the more x-ray photons are emitted from the anode. Many x-raydevices have meters to measure current.

Determining Total Power

Total power equals voltage times current (W = V x A). For example,a 10-kV device with a current of 1 mA produces 10 W of power.



Interaction with Matter

Scattering

When x-rays pass through any material, some will be transmitted,some will be absorbed, and some will scatter. The proportionsdepend on the photon energy and the type of material.

X-rays can scatter off a target to the surrounding area, off a walland into an adjacent room, and over and around shielding. Acommon mistake is to install thick shielding walls around an x-raysource but ignore the need for a roof, based on the assumptionthat x-rays travel in a straight line. The x-rays that scatter over andaround shielding walls are known as skyshine.

Source Shield

X

X

X

Air Scatter (Skyshine)

Figure 5. Skyshine

Shielding

High-energy x-ray photons are more penetrating than low-energyphotons. This makes high-energy photons more difficult to shield.Thicker shielding may be required, or if the shielding thickness isfixed, high-energy photons will penetrate more often than low-energy photons. Varying thicknesses of lead, concrete, and steelare most effective in shielding against x-rays.



Interaction with Matter—continued

Filtration

High- and low-energy photons are sometimes referred to hardand soft x-rays, respectively. Because hard x-rays are morepenetrating, they are more desirable for radiography (producing aphotograph of the interior of the body or a piece of apparatus). Softx-rays are less useful for radiography because they are absorbednear the surface.

A filter such as a few millimeters of aluminum can be used toharden the beam by absorbing most of the low-energy photons.The remaining high-energy photons are more penetrating.

Implications of Photon Energy and Total Power

High-energy photons penetrate deeply into the body, resulting in adeep dose and damage to the internal organs. Low-energy photonsare absorbed in the top layers of tissue, resulting in a shallow doseand damage mostly to the skin.

The greater the number of photons, and therefore the greater thetotal energy, the more damage is caused to whatever part of thebody the photons strike. This is measured in units of rad or rem,defined as the result of 0.01 W for 1 second in 1 kilogram of humantissue (0.01 W-sec/kg = 1 rad = 1 rem, for x-rays). Note that aconcentrated beam of x-rays could deposit all of its energy in muchless than 1 kilogram of tissue. For example, 0.01 W for 1 second in1 gram would result in 1,000 rem of damage.

A 100-keV photon is more hazardous than a 10-keV photon, and10 W are more hazardous than 1 W, but the precise hazardsdepend on what part of the body is exposed, how far the x-rayphoton penetrates, and other factors discussed in Unit 3.



Self-Assessment

1. X-rays are similar to other types of electromagnetic radiationbecause all consist of (EO1)

a. electrons

b. photons

c. protons

d. neutrons

2. X-rays are different from some other types of electromagneticradiation because x-rays are (EO1)

a. electrons

b. ionizing

c. nonionizing

d. atoms

3. Which of the following types of radiation is the most similar tox-rays? (EO2)

a. microwaves

b. infrared

c. ultraviolet

d. gamma rays

4. In an x-ray device, x-rays are emitted from the (EO3)

a. anode

b. vacuum

c. cathode

d. diode

5. Production of x-rays by bremsstrahlung is generally increasedwhen charged particles with _____ mass hit an anode with_____ atomic weight. (EO4)

a. small, low

b. large, low

c. small, high

d. large, high

✓




6. In an x-ray device, photon energy depends on _____ and thenumber of photons produced depends on _____. (EO5)

a. current, voltage

b. current, filtration

c. voltage, current

d. voltage, filtration

7. Which of the following best describes the safety situation whenthe voltage meter on an x-ray device is on and the currentmeter reads zero, assuming the meter has not malfunctioned?(EO6)

a. there are no x-rays

b. there may be a small current, too small to read, producingsome x-rays

c. the x-ray hazard is unaffected by the current or voltage

d. the x-ray energy increases as the current and voltagedecrease

8. When filtration is used in an x-ray device to harden the beam,the remaining photons are (EO6)

a. low-energy, more penetrating

b. low-energy, less penetrating

c. high-energy, more penetrating

d. high-energy, less penetrating

9. When x-rays interact with matter, will they be absorbed,transmitted, or scattered? (EO7)

a. absorbed

b. transmitted

c. scattered

d. some of each

10. Scattering of x-rays by air may result in increased (EO7)

a. skyshine

b. power

c. current

d. voltage

✓




11. When comparing 10-keV with 100-keV x-rays, the shieldingrequired is likely to be (EO7)

a. greater for 10 keV

b. greater for 100 keV

c. the same for each

d. impossible for 10 keV and easy for 100 keV

12. The dose received from x-rays is a measure of (EO8)

a. the energy absorbed per unit mass

b. the power absorbed per unit photon

c. the photons transmitted per unit weight

d. the electron volts scattered per unit watt

✓



Notes . . .



Answers

1. b

2. b

3. d

4. a

5. c

6. c

7. b

8. c

9. d

10. a

11. b

12. a

Unit 3: Biological Effects


Unit Objectives

Major Objective

Upon completion of this unit, you will understand the biologicaleffects of x-rays and the importance of protective measures forworking with or around x-rays.



EO1 the early history of x-rays and the consequences of workingwith or around x-rays without protective measures,

EO2 factors that determine the biological effects of x-ray exposure,

EO3 the differences between thermal and x-ray burns,

EO4 the signs and symptoms of an acute exposure to x-rays,

EO5 the effects of chronic exposure to x-rays, and

EO6 the difference between somatic and heritable effects.



Early History of X-Rays

Discovery of X-Rays

X-rays were discovered by German scientist Wilhelm Roentgen.In early November 1895, Roentgen was investigating high-voltageelectricity and noticed that a nearby phosphor glowed in the darkwhenever he switched on the apparatus. He quickly demonstratedthat these unknown “x” rays, as he called them, traveled in straightlines, penetrated some materials, and were stopped by densermaterials. He continued experiments with these “x” rays andeventually produced an x-ray picture of his wife’s hand showingthe bones and her wedding ring. In early January 1896, Roentgenmailed copies of this picture along with his report to fellowscientists.

By February 1896, the first diagnostic x-ray in the United Stateswas taken, followed quickly by the first x-ray picture of a fetus inutero. By March, the first dental x-rays were taken. In that samemonth, French scientist Henri Becquerel was looking forfluorescence effects from the sun, using uranium on a photographicplate. The weather turned cloudy so he put the uranium and thephotographic plate into a drawer. When he developed the plates afew weeks later, he realized he had made a new discovery. Hisstudent, Marie Curie, named it radioactivity.

Figure 6. Roentgen’s First X-Ray



Early History of X-Rays—continued

Discovery Of Harmful Effects

Because virtually no protective measures were used in those earlydays, people soon learned about the harmful effects of x-rays.X-ray workers were exposed to very large doses of radiation, andskin damage from that exposure was observed and documentedearly in 1896. In March of that year, Thomas Edison reported eyeinjuries from working with x-rays. By June, experimenters werebeing cautioned not to get too close to x-ray tubes. By the end ofthat year, reports were being circulated about cases of hair loss,reddened skin, skin sloughing off, and lesions. Some x-ray workerslost fingers, and some eventually contracted cancer. By the early1900s, the potential carcinogenic effect of x-ray exposure inhumans had been reported.

Since that time, more than a billion dollars have been spent in thiscountry alone on radiation effects research. The biological effectsof exposures to radiation have been investigated. National andinternational agencies have formed to aid in the standardization ofx-ray use to ensure safer practices.



Biological Effects of Radiation

X-rays can penetrate deeply into the human body, strip electronsfrom orbit, and thereby break or modify chemical bonds withincritical biological molecules that make up the cells. This processcan cause cell injury and even cell death, depending on the doseand dose rate of the exposure.

In some cases, altered cells are able to repair the damage. In othercases, the effects are passed to daughter cells through cell divisionand after several divisions can result in a group of cells with alteredcharacteristics. The division of these cells may be the first step intumor or cancer development. If enough cells in a body organ areinjured or altered, the functioning of the organ can be impaired.

Cell Nucleus

Cell

Chromosome

Radiation

Figure 7. Effects of Radiation on a Cell



Factors that Determine Biological Effects

Several factors contribute to the biological effects of x-rayexposure, including

¥ dose rate,

¥ total dose received,

¥ energy of the radiation,

¥ area of the body exposed,

¥ individual sensitivity, and

¥ cell sensitivity.

Dose Rate

Depending on the period of time over which it is received, a doseis commonly categorized as acute or chronic. An acute dose isreceived in a short period (seconds to days); a chronic dose isreceived over a long period (months to years).

For the same total dose, an acute dose is more damaging than achronic dose because the cell does not have time to repair anydamage between “hits.” With an acute dose, a cell may receivemany “hits” and the effects are cumulative.

Total Dose Received

The higher the total amount of radiation received, the greater theeffects observed. The effects of an acute dose of more than 100rem are easily observed. However, the signs and symptoms of anacute dose of amounts less than 10 to 25 rem are not easilyobserved.

The effects of a chronic dose are also difficult to observe. Althoughchronic effects have not been observed directly, it is assumed thatthe higher the total dose, the greater the risk of contracting canceror other long-term effects.



Factors that Determine Biological Effects—continued

Energy of the Radiation

The energy of x-rays can range from less than 1 keV up to morethan 10 MeV, but are typically 40 to 100 keV. The higher the energyof the x-ray, the greater the penetration into body tissue (deepdose) and the higher the probability of damage to internal organs,bone, or bone marrow, the site of blood-forming tissue. Lowerenergy x-rays are absorbed in the first few centimeters of tissue(shallow dose) and can cause damage to the skin but less damageto the internal organs of the body.

Area of the Body Exposed

Just as a burn to the majority of the body is more damaging than aburn confined to a small area, similarly a radiation dose to thewhole body, which contains the vital organs and blood-formingtissue, is much more damaging than an exposure to only theextremities. In addition, the larger the area exposed, the moredifficult it is for the body to repair the damage.

Individual Sensitivity

Some individuals are more sensitive to radiation than others. Age,gender, lifestyle, and overall health can have an effect on how thebody responds to radiation dose.

Cell Sensitivity

Some cells are more sensitive to radiation than others. Cells thatare more sensitive to radiation are radiosensitive; cells that areless sensitive to radiation are radioresistant.

Cells that are nonspecialized such as sperm and ovum cells or cellsthat are actively dividing such as hair follicle and gastrointestinalcells are the most radiosensitive. Cells that are specialized (mature)or cells that are less-actively dividing such as bone, muscle, orbrain cells are more radioresistant.



Somatic Effects

Somatic effects are biological effects that occur in the individualexposed to radiation. Somatic effects may result from acute orchronic doses of radiation.

Early Effects

The most common injury associated with the operation of x-rayanalysis equipment occurs when a part of the body, usually a hand,is exposed to the primary x-ray beam. Both x-ray diffraction andfluorescence analysis equipment generate high-intensity x-rays thatcan cause severe and permanent injury if any part of the body isexposed to the primary beam.

The most common injury associated with the operation of industrialx-ray equipment occurs when an operator is exposed to the primaryx-ray beam or almost touches the source for as little as a fewseconds.

These types of injuries are sometimes referred to as radiationburns.

X-Ray Burns versus Thermal Burns

Most nerve endings are near the surface of the skin, so they giveimmediate warning of a surface burn such as you might receivefrom touching a high-temperature object. In contrast, high-energyx-rays penetrate the outer layer of skin that contains most of thenerve endings so you may not feel an x-ray burn until the damagehas been done.

X-ray burns do not harm the outer, mature, nondividing skin layers.Rather, the x-rays penetrate to the deeper, basal skin layer,damaging or killing the rapidly dividing germinal cells that weredestined to replace the outer layers that slough off. Following thisdamage, the outer cells that are naturally sloughed off are notreplaced. Lack of a fully viable basal layer of cells means that x-rayburns are slow to heal, and in some cases, may never heal.Frequently, such burns require skin grafts. In some cases, severex-ray burns have resulted in gangrene and amputation of a finger.

The important variable is the energy of the radiation. Heat radiationis infrared, typically 1 eV; sunburn is caused by ultraviolet, typically4 eV; x-rays are typically 40 to 100 keV.



Somatic Effects—continued

Signs and Symptoms of Exposure to X-Rays

~500 rem. An acute dose of about 500 rem to a part of the bodycauses a radiation burn equivalent to a first-degree thermal burn ormild sunburn. Typically, there is no immediate pain, but a sensationof warmth or itching occurs within about a day after exposure. Areddening or inflammation of the affected area usually appearswithin a day and fades after a few more days. The reddening mayreappear as late as two to three weeks after the exposure. A dryscaling or peeling of the irradiated portion of the skin is likely tofollow.

If you have been working with or around an x-ray device and younotice an unexplained reddening of your skin, notify your supervisorand the Occupational Medicine Group (ESH-2). Aside fromavoiding further injury and guarding against infection, furthermedical treatment will probably not be required and recoveryshould be fairly complete.

An acute dose of about 600-900 rem to the lens of the eye causesa cataract to begin to form.

>1,000 rem. An acute dose of greater than 1,000 rem to a part ofthe body causes serious tissue damage similar to a second-degreethermal burn. First reddening and inflammation occurs, followed byswelling and tenderness. Blisters will form within one to threeweeks and will break open leaving raw, painful wounds that canbecome infected. Hands exposed to such a dose become stiff andfinger motion is often painful. If you develop symptoms such asthese, seek immediate medical attention to avoid infection andrelieve pain.

An even larger acute dose causes severe tissue damage similar toa scalding or chemical burn. Intense pain and swelling occurs,sometimes within hours. For this type of radiation burn, seekimmediate medical treatment to reduce pain. The injury may notheal without surgical removal of exposed tissue and skin grafting tocover the wound. Damage to blood vessels also occurs, which canlead to gangrene and amputation.




A typical x-ray device can produce such a dose in about 3 seconds.For example, the dose rate from an x-ray device with a tungstenanode and a beryllium window operating at 50 keV and 20 mAproduces about 900 rem per second at 7.5 cm. The dose rate canbe estimated from the formula

50 V I

rem/sec = ———— ,

R2

where V is the potential in volts, I is the current in amperes, andR is the distance in centimeters.

Latent Effects

The probability of a latent effect appearing several years after anacute exposure to radiation depends on the amount of the dose.The higher the dose, the greater the risk of developing a long-termeffect. When an individual receives a large accidental dose, andthe prompt effects of that exposure have been dealt with, there stillremains a concern about latent effects years after the exposure.Although there is no unique disease associated with exposure toradiation, the concern usually centers around the possibility ofdeveloping cancer. If the exposure is directly to the lens of the eye,the development of cataracts is the expected latent effect.

Chronic Effects

Chronic somatic effects may not appear until several years afterexposure to radiation. Chronic effects result from doses of radiationreceived over a long period. The higher the cumulative dose, thegreater the risk of developing a chronic effect. One chronic effect iscataracts. Chronic dose to the lens of the eye can result incataracts and other optical problems if the total dose exceeds600 rem.




Risk of Developing Cancer from Chronic Exposure

The risk of cancer from chronic low doses of radiation cannotbe estimated precisely because the risk is so low it cannot bedistinguished from natural causes. Thus, estimates of the risk fromlow doses must be inferred from those developed for the effectsobserved at acute high doses.

The Fifth Committee on the Biological Effects of Ionizing Radiation(BEIR V) estimates the risk to be 0.8% for an acute dose of 10 rem.This risk estimate for high doses was developed through studies ofJapanese atomic bomb survivors, uranium miners, radium watch-dial painters, and radiotherapy patients.

Below 10 rem, effects of chronic, low doses have not beenmeasured. Therefore, risk estimates for low doses have beeninferred from high-dose data to provide conservative protectionguidelines for exposure.

Effects of Prenatal Exposure (Teratogenic Effects)

The embryo/fetus is especially sensitive to radiation. The embryois in the most sensitive stage with both actively dividing andnonspecialized cells right after fertilization. If you are planning apregnancy, you should seek advice from the Reproductive HealthHazards Program (RHHP) Committee through ESH-2 or the Policyand Program Analysis Group (ESH-12) and keep your radiationdose ALARA.

If you become pregnant, you are strongly encouraged to declareyour pregnancy in writing to your supervisor, ESH-2, or ESH-12and to keep your total accumulated dose ALARA during the ninemonths of pregnancy. The dose limit for a declared pregnantworker is 500 mrem during the term of the pregnancy, with no morethan 0.05 rem per month.



Heritable Effects

Somatic Effects

Heritable Effects

Appear inexposed person

Appear in futuregenerations of exposed person

Figure 8. Somatic vs. Heritable Effects

Heritable effects are biological effects that are inherited by childrenfrom their parents at conception. Irradiation of the reproductiveorgans can damage and alter cells that are involved in conceptionand can alter heritable information passed on to offspring.

Heritable effects have been observed in large scale experimentswith fruit flies and mice irradiated with large doses of radiation.Heritable effects have not been established in humans. However,the probability of heritable effects in humans is prudently inferredfrom the animal data.

The heritable effects of ionizing radiation do not result in biologicalconditions in the offspring that are uniquely different from theeffects that occur naturally. Extensive observations of the childrenof Japanese atomic bomb survivors have not revealed anystatistically significant health effects.

Note: Teratogenic (congenital) effects are not heritable effects.Teratogenic effects are not inherited; they are caused by the actionof agents such as drugs, alcohol, radiation, or infection to anunborn child in utero. Teratogenic effects occurred in children whowere irradiated in utero by the atomic bombs at Hiroshima orNagasaki.



Self-Assessment

1. X-rays were discovered by Wilhelm Roentgen in 1895 while hewas (EO1)

a. x-raying his wife’s hand

b. investigating fluorescence of uranium

c. experimenting with high-voltage vacuum tubes

d. visiting Thomas Edison

2. If the total accumulated dose from x-rays to human tissueremains the same, how does the dose rate affect the biologicaldamage? (EO2)

a. acute doses are generally more serious

b. chronic doses are generally more serious

c. the dose rate must exceed 5 mrem per hour to have aneffect

d. the dose rate makes no difference

3. Which of the following types of cells is most radiosensitive?(EO2)

a. skin

b. bone

c. muscle

d. gastrointestinal

4. Which of the following types of cells is most radioresistant?(EO2)

a. gastrointestinal

b. brain

c. sperm

d. ovum

5. One of the first signs of an x-ray burn to the extremities is(EO3)

a. loss of hair

b. cancer

c. nausea

d. reddening of the skin

✓




6. When comparing an x-ray burn with a thermal burn, an x-rayburn is likely to be _____ painful immediately, and _____painful later. (EO4)

a. less, less

b. less, more

c. more, less

d. more, more

7. Acute effects occur in a _____ period; chronic effects occurover a _____ period. (EO5)

a. long, longer

b. long, short

c. short, long

d. short, shorter

8. Chronic exposure of the eye to x-rays can result in (EO5)

a. acute effects

b. burns

c. cataracts

d. puncture

9. Somatic effects occur in the ______, heritable effects occur inthe ______ (EO6)

a. children, exposed person

b. children, body

c. exposed person, children

d. skin, hair

✓



Answers

1. c

2. a

3. d

4. b

5. d

6. b

7. c

8. c

9. c

Unit 4: Radiation Detection


Unit Objectives

Major Objective

Upon completion of this unit, you will understand which radiationmonitoring instruments and which personnel monitoring devices areappropriate for detecting x-rays.



EO1 the requirements for surveying x-ray devices,

EO2 the instruments used for x-ray detection and measurement,and

EO3 the devices used for personnel monitoring.



Radiation Surveys

Radiation protection surveys are conducted on all new or newlyinstalled intentional x-ray devices by the X-Ray Device ControlOffice and resurveyed annually and as specified in LS107-03.0.A LANL x-ray compliance label certifies that the device has beensurveyed and that safe operating requirements have been met.

WARNINGDO NOT USE THIS MACHINE

It does not meet applicableradiation safety standards

and operational safety requirements

X-Ray Device ControlOffice Representative

Phone

Date PN

X-RAY COMPLIANCE LABEL

PN: ___________________________

Resurvey Due: ________________ ______________ Month Year

_____________________________ ______________X-Ray Device Control Office Rep. Date

This machine has been surveyed and found tomeet applicable radiation safety standards

and operational safety requirements.

Figure 9. Compliance and Warning Labels

When significant safety hazards are identified, a LANL warninglabel is attached to the x-ray device, indicating that it must not beused. After any necessary repairs or modifications are completed,the device must be resurveyed by the X-Ray Device Control Office.

Radiation Monitoring Instruments

External exposure controls used to minimize the dose equivalentto workers are based on the data taken with portable radiationmonitoring instruments during a radiation survey. An understandingof these instruments is important to ensure that the data obtainedare accurate and appropriate for the source of radiation.

Many factors can affect how well the survey measurement reflectsthe actual conditions, including

¥ selection of the appropriate instrument based on the type andenergy of radiation and the radiation intensity;

¥ correct operation of the instrument based on the instrumentoperating characteristics and limitations; and

¥ calibration of the instrument to a known radiation field similar intype, energy, and intensity to the radiation field to be measured.



Radiation Monitoring Instruments—continued

Instruments Used for X-Ray Detection and Measurement

Ebe

rline

CA

UTI

ON

XX

XX

XX

XX

XX

XX

XX

XXX

X

XX

XX

XX

XX

XX

XX

XX

XXX

X

XX

XX

XX

XX

XX

XX

XX

XXX

X

XX

XX

XX

XX

XX

XX

XX

XXX

XX

XX

XX

XX

XX

X

XX

XX

XXX

XXXX

ESPEberlineSmartPortable

GM Counter Ion Chamber

Eberline

2 3 4

5

ION CHAMBERMODEL RO - 3C SERIAL 724

eberline

OFF

550

ZEROBAT 3

BAT 2

mR/h

Figure 10. Detection and Measurement Instruments

X-ray-device operators often use a radiation monitoring instrumentfor the detection of x-rays, for example, to verify that the deviceis off before entry into the area. The measurement of x-rays isnormally the job of a qualified radiological control technician (RCT).

Instruments such as Geiger-Mueller (GM) counters, which countindividual photons in counts per minute (cpm), are sensitive tox-rays. However, because a low-energy and a high-energy photonare both assigned one count, the GM counters tend to overrespondto the low-energy photons. A thin-windowed GM counter is theinstrument of choice for the detection of x-rays.

Measurement of radiation dose rates and surveys of recordrequires an instrument that reads roentgen or rem (R/hour,mR/hour, rem/hour, mrem/hour). Ion chambers, which detectcurrent instead of counting pulses, have the flattest energyresponse.



Personnel Monitoring Devices

Whole-Body Dosimeters

Operators of intentional x-ray devices wear whole-body dosimeterssuch as thermoluminescent dosimeters (TLDs). TLDs canaccurately measure radiation doses as low as 10 mrem and areused to assess the dose of record. The records are available to theworkers from ESH-12 at any time. Hazardous situations orpractices that otherwise may go unnoticed can be spotted byhigher-than-usual dosimeter readings.

Whole-body dosimeters should be worn so they represent the doseto the trunk of the body. Standard practice is to wear a dosimeterbetween the neck and the waist, but in specific situations suchas nonuniform radiation fields, special considerations may apply.Some dosimeters have a required orientation with a specific sidefacing out.

LASL

Pocket Dosimeter

Whole-Body Dosimeter

Figure 11. Personnel Monitoring Devices

Pocket Dosimeters

Pocket ionization chambers such as pencil dosimeters or electronicdosimeters are used in higher radiation areas. Pencil dosimetersare manufactured with scales in several different ranges; the0–500 mR range, marked in increments of 20 mR, is most oftenused. Pocket dosimeters, which give an immediate readout of theradiation dose, are supplemental and used primarily as ALARAtools.



Personnel Monitoring Devices—continued

Alarming Dosimeters

In higher radiation areas, an alarming dosimeter may be used toprovide an audible warning of radiation. This contributes to keepingdoses ALARA by increasing a worker’s awareness of the radiation.

Special Considerations

Specific applications may require special considerations. Forexample, low-energy x-rays will not penetrate the walls of somedosimeters, and flash x-ray devices produce a very short pulse thatis not correctly measured by most dosimeters.

If you think you may need special dosimeters or instruments,contact an RCT or the ESH-12 X-Ray Device Control Office,7-8080.



Self-Assessment

1. An x-ray device must be surveyed (EO1)

a. annually

b. semiannually

c. quarterly

d. weekly

2. The instrument of choice to detect x-rays, in cpm, and whichis very sensitive, is a (an) (EO2)

a. personnel contamination monitor

b. thin layer of ZnS scintillator

c. thin-windowed GM counter

d. ion chamber

3. The best instrument to measure the dose rate for x-rays,in mR/hour, is a (an) (EO2)

a. personnel contamination monitor

b. thin layer of ZnS scintillator

c. thin-windowed GM counter

d. ion chamber

4. A TLD can measure doses as low as (EO3)

a. 0.5 mR per hour

b. 10 mrem

c. 10 rem

d. 5 R per hour

✓




5. When working with an intense source of x-rays, a pocketchamber is used to (EO3)

a. shield the user from radiation

b. provide an official record of the dose

c. provide an immediate reading of the dose

d. measure the dose to the fingers

6. An alarming dosimeter provides (EO3)

a. a very accurate measurement of the total dose

b. an official record of the dose

c. an audible warning of the dose or dose rate

d. a reading of the dose to the fingers

✓



Answers

1. a

2. c

3. d

4. b

5. c

6. c

Unit 5: Protective Measures


Unit Objectives

Major Objective

Upon completion of this unit, you will understand about protectivemeasures that restrict or control access to x-ray areas and devicesor warn of x-ray hazards and work documents that provide specificprocedures to ensure safe operation of x-ray devices.



EO1 the purpose of posting,

EO2 the defining conditions and entry requirements for areascontrolled for radiological purposes,

EO3 the requirements for labels and warning signals,

EO4 the requirements for fail-safe interlocks,

EO5 the criteria for determining appropriate shielding, and

EO6 the purpose of an SOP and RWP and when each is used.



Radiological Postings

Purpose of Posting

The two primary reasons for radiological posting are

¥ to inform workers of the area radiological conditions and

¥ to inform workers of the entry requirements for the area.

To maintain exposure to radiation ALARA, access to areas ordevices in which one can receive more than 100 mrem per yearare restricted.

CONTROLLED AREAAccess Controlled for Radiological Purposes

Contamination and External Radiation Hazards

May Exist within this Area

ENTRY REQUIREMENTS

(FACILITY-SPECIFIC REQUIREMENTS)

NOTICE

GRAVE DANGER

LOCATION

VERY HIGHRADIATION AREA

Max. Dose Rate

DATE RCT

Dose Rate Exceeds 500 rad/hr

rad/hr

SPECIAL CONTROLS REQUIRED FOR ENTRY

CONTACT FOR REQUIREMENTS

RADIOLOGICAL BUFFER AREA

Elevated Contamination, Airborne Radioactivity, and

External Radiation Hazards May Exist within this Area

CAUTION

ENTRY REQUIREMENTS

(FACILITY-SPECIFIC REQUIREMENTS)

RADIATION AREADose Equivalent Rate Exceeds 5 mrem/hr

CONTACT HEALTH PHYSICS

RAD WORKER 1 TRAINING

OTHER

TLD BADGE

LOCATION

Max. Dose Equivalent RateDATE RCT

mrem/hr

SUPPLEMENTAL DOSIMETER

RWP

CAUTION

ENTRY REQUIREMENTS

DANGER

LOCATION

HIGH RADIATION AREA

Max. Dose Equivalent Rate

DATE RCT

Dose Equivalent Rate Exceeds 100 mrem/hr

mrem/hr

ENTRY REQUIREMENTS

CONTACT HEALTH PHYSICS

RAD WORKER 2 TRAINING SUPPLEMENTAL DOSIMETER

TLD BADGE RWP

OTHER

Figure 12. Radiological Postings



Radiological Postings—continued

Posting Requirements

Areas controlled for radiological purposes must be posted witha black or magenta standard three-bladed radiological warningsymbol or trefoil, on a yellow background. At LANL, black on yellowis used for most postings. Additionally, yellow and magenta ropes,tapes, chains, or other barriers can be used to mark the boundariesof radiological areas.

Postings and barriers must be clearly visible from all accessibledirections. Postings on doors should remain visible when doors areopen or closed. Postings should state the radiation dose rate andthe entry requirements. If more than one radiological hazard existsin an area, the posting should identify each hazard. Postings thatindicate an intermittent radiological condition should include astatement specifying when the condition exists such as when a redlight is on.

The same posting requirements apply for x-ray or gamma radiationas for any other type of radiation. Areas controlled for radiologicalpurposes are posted as shown in the following table. Most of thesearea definitions are standard throughout the United States.

Posting Requirements

Area Posting Defining Condition Entry Requirements

Controlled Area >100 mrem/yearpossible

General EmployeeRadiological Training

RadiologicalBuffer Area

n/a facility-specific

Radiation Area >5 mrem/hour, but≤100 mrem/hour

Radiological Worker ITraining

TLD

RWP (as required)

HighRadiation Area

>100 mrem/hour, but≤500 rad/hour

Radiological Worker ITraining

TLD

supplemental dosimetry

RWP

Very HighRadiation Area

>500 rad/hour special requirements



Labels

The control panel of an intentional x-ray device must be labeledwith the words “CAUTION—THIS EQUIPMENT PRODUCESX-RAYS WHEN ENERGIZED.”

An x-ray device that has been surveyed by the X-Ray DeviceControl Office and meets safe operating requirements displaysa LANL x-ray compliance label. A device that fails to meet allappropriate safety requirements displays a warning label indicatingthat the device must not be used.

An x-ray device must also display a label stating that the X-RayDevice Control Office must be notified if the machine is moved,transferred, or altered.

Warning Devices

CAUTIONRADIATION

This Equipment ProducesX-RADIATION When Energized

SHUTTEROPEN

X-RAYS ON

X-RAYS ON

FAIL SAFE

Figure 13. Labels and Indicator Lights

Warning signals are used to alert workers to the status of the x-raytube. Visible indicators that are activated automatically when poweris available for x-ray production include

¥ a current meter on the x-ray device control panel,

¥ a warning light labeled “X-RAYS ON” near or on the x-raydevice control panel,

¥ a warning light or rotating beacon near the x-ray device or thex-ray room door, and

¥ a “SHUTTER OPEN” indicator on or near the x-ray device.



Warning Devices—continued

For x-ray systems with an open beam in a shielded room, audibleand visible evacuation warning signals must be activated at least20 seconds before x-ray production can be started. Any personwho is inside the exposure room when warning signals come onshould immediately leave the room and activate the scram switchon the way out. The scram switch is an emergency off switchdesigned to shut down the x-ray system immediately.

Interlocks

Fail-safe interlocks are provided on doors and access panels ofx-ray devices so that x-ray production is not possible when theyare open. A fail-safe interlock is designed so that any failure thatcan reasonably be anticipated will result in a condition in whichpersonnel are safe.

Interlocks must be tested by the x-ray-device custodian at leastevery six months for proper operation. The interlock test proceduremay be locally specified, but typically is as follows:

1. Energize the x-ray tube.

2. Open each door or access panel one at a time.

3. Observe x-ray warning light or current meter at the controlpanel.

4. Record the results in a log.

Shielding

Analytical Systems

For analytical x-ray machines such as x-ray fluorescence anddiffraction systems the manufacturer provides shielding inaccordance with ANSI N43.2. However, prudent practice requiresthat any device or source that involves radiation should besurveyed to determine the adequacy of the shielding.



Shielding—continued

Enclosed-beam systems have sufficient shielding so that the doserate does not exceed 0.25 mrem per hour under normal operatingconditions. The dose rate may be difficult to evaluate. Accordingto ANSI N43.2, this requirement is met if the shielding is at leastequal to the thickness of lead specified in the table below for themaximum rated anode current and potential.

Shielding Requirements

Anode Current Millimeters of Lead

(mA) 50 kVp 70 kVp 100 kVp

20 1.5 5.6 7.7

40 1.6 5.8 7.9

80 1.6 5.9 —

160 1.7 — —

Industrial Systems

Some industrial x-ray systems such as the cabinet x-ray systemsused for airport security are completely enclosed in an interlockedand shielded cabinet. Larger systems such as medical x-ray unitsare enclosed in a shielded room to which access is restricted.Shielding for x-ray rooms is designed to handle the most severeoperating conditions of the x-ray machine. RCTs periodically verifythat the shielding integrity has not deteriorated.

X-Ray Device Control Office personnel develop recommendationsfor shielding based on the following information:

¥ type of source,

¥ voltage or energy,

¥ amperage or current,

¥ contemplated use,

¥ expected workload,

¥ structural details of the building, and

¥ type of occupancy for all affected areas.



Work Documents

Standard Operating Procedures

Each intentional x-ray device must have an SOP to ensure thatthe x-ray device will be operated safely and efficiently. As specifiedin LS107-03.0, SOPs should include the following:

¥ description of the x-ray device and its intended use;

¥ normal x-ray parameters (peak power, current, exposure time,x-ray source-to film distance, etc.);

¥ procedures for proper sample preparation, alignmentprocedures, or handling of object to be radiographed;

¥ description of all safety hazards (electrical, mechanical,explosive, and radiation) associated with the operation of the x-ray device;

¥ description of the safety features (interlocks, warning signals,etc.) and any other safety precautions;

¥ procedures for performing interlock tests and the recommendedfrequency of such tests;

¥ required operator training and dosimetry;

¥ posting of signs and labels;

¥ x-ray-device safety checklist (items to be checked before use);

¥ actions to take in the event of an abnormal occurrence oremergency; and

¥ use of a radiation monitoring instrument upon entry into thearea, as specified in ANSI N43.3 for some x-ray devices.

X-Ray Device Control Office personnel review each SOP to verifythat it establishes appropriate safety practices and can assist theoperating groups in preparing or modifying an SOP. The currentSOP must be kept near the x-ray device.

Hazard Control Plan

The SOP should be incorporated into a hazard control plan (HCP),as defined in Laboratory implementation requirement (LIR) 300-00-01.0, Safe Work Practices, and LIR300-00-02.0, Documentationof Safe Work Practices. In addition to defining the work, the HCPmust identify the hazards and describe the controls. Existingdocumentation provided by the manufacturer is normally sufficientto identify the hazards and describe the controls, if the apparatushas not been modified and will be used as designed.



Work Documents—continued

Radiological Work Permits

General RWPs are used to establish radiological controls for entryinto radiological areas. They serve to

¥ inform workers of area radiological conditions,

¥ inform workers of entry requirements for the areas, and

¥ provide a means to relate radiation doses to specific workactivities.

A job-specific RWP is used to control nonroutine operations or workareas with changing radiological conditions.

RWPs are used in conjunction with x-ray devices when any of thefollowing situations exist:

¥ a compliance label for a newly acquired x-ray device cannot beissued because the SOP for that device has not yet been writtenand approved,

¥ a portable x-ray device will be used only for a short period, tooshort to warrant writing an SOP, or

¥ a nonroutine event requires that an operator must enter theradiation exposure room when the x-ray beam is on and x-raysare being produced so that either a High or Very High RadiationArea exists.

Integrated Safety Management and RWPs

Integrated Safety Management (ISM) is the framework thatsupports LANL's commitment to “Safety First.” ISM involves fivesteps that are to be incorporated into all work activities. The RWPfollows these five steps, as follows:

1. Define the work. The work to be performed is defined in the firstsection, “General Information.”

2. Identify the hazards. The radiation hazards are identified in thesecond section, “Pre-Job Radiological Conditions.”

3. Implement Controls. The work controls are specified in the thirdsection, “Radiological Protection Requirements.”

4. Do the work safely. The fourth section specifies “hold points,”which are checks to ensure that dose levels are as expected.

5. Provide feedback. The final two sections, “Post-Job RadiologicalConditions” and “Review,” ensure that lessons learned arecommunicated to workers performing similar jobs in the future.



Self-Assessment

1. A primary purpose of posting radiological areas is to (EO1)

a. prevent workers from entering radiological areas

b. inform workers of the radiological conditions

c. allow RCTs to measure the dose

d. eliminate all occupational doses at LANL

2. The types of posting used for Radiation and High RadiationAreas at LANL (EO2)

a. have a different meaning at each facility

b. have a different meaning at each DOE site

c. are standard throughout the United States

d. are sometimes in Spanish at LANL

3. Radiological Worker Training is required for all individuals who(EO2)

a. work at LANL

b. do not wear TLDs

c. enter Controlled Areas

d. enter Radiation Areas

4. In a Radiation Area the dose rate is (EO2)

a. 5 to 100 mrem per year

b. 5 to 100 rem per hour

c. 5 to 100 mrem per hour

d. 100 to 500 mrem per hour

5. Whenever x-rays are on, which of the following is required?(EO3)

a. a bell must ring continuously

b. a warning light must read “X-RAYS ON”

c. a line manager must be in the room

d. a scram switch must be pressed

✓




6. All of the following are true for x-ray interlocks, except (EO4)

a. they must be fail-safe

b. they must be tested every six months

c. tests must be documented

d. they must be computer controlled

7. According to ANSI 43.2, approximately how much leadshielding is required for 70-kVp x-rays? (EO5)

a. 2 mm

b. 6 mm

c. 8 mm

d. 12 mm

8. An RWP is generally used instead of an SOP for (EO6)

a. routine work

b. nonroutine work

c. all work with x-rays

d. all work with radiation

✓



Notes . . .

_



Answers

1. b

2. c

3. d

4. c

5. b

6. d

7. b

8. b

Unit 6: X-Ray-Generating Devices


Unit Objectives

Major Objective

Upon completion of this unit, you will understand the categories ofx-ray-generating devices and the risks associated with each.



EO1 the difference between incidental and intentional x-raydevices;

EO2 the types of analytical and industrial x-ray devices;

EO3 the safety features essential for operation of analyticalenclosed- and open-beam systems; and

EO4 the safety features essential for operation of industrialcabinet, exempt shielded, shielded, unattended, and openinstallations.



Intentional and Incidental Devices

X-ray systems are divided into two broad categories: intentionaland incidental.

An incidental x-ray device produces x-rays that are not wanted orused as a part of the designed purpose of the machine. Examplesof incidental systems are computer monitors, televisions, electronmicroscopes, high-voltage electron guns, electron-beam weldingmachines, and electrostatic separators.

An intentional x-ray device is designed to generate an x-ray beamfor a particular use. Examples include x-ray diffraction andfluorescence analysis systems, flash x-ray systems, medical x-raymachines, and industrial cabinet and noncabinet x-ray installations.

Intentional x-ray devices are further divided into two subcategories:analytical and industrial. ANSI N43.2 applies to analytical x-raysystems and ANSI N43.3 applies to industrial systems.



Incidental X-Ray Devices

At a research laboratory such as LANL, many devices produceincidental x-rays. Any device that combines high voltage and avacuum could, in principle, produce x-rays. For example, atelevision or computer monitor generates incidental x-rays, butin modern designs the intensity is small, much less than 0.5 mRper hour.

Occasionally, this hazard is recognized only after the device hasoperated for some time. If you suspect an x-ray hazard, contact anRCT or the ESH-12 X-Ray Device Control Office (7-8080) to surveythe device.

Electron Microscopes

The exposure rate during any phase of operation of an electronmicroscope at the maximum-rated continuous beam current for themaximum-rated accelerating potential should not exceed 0.5 mRper hour at 2 inches (5 cm) from any accessible external surface.

Intentional Analytical X-Ray Devices

Analytical X-Ray Devices

Analytical x-ray devices use x-rays for diffraction or fluorescenceexperiments as research tools, especially in materials science.ANSI N43.2 defines two types of analytical x-ray systems: enclosedbeam and open beam.

Safety requirements and features for analytical systems aredetailed in Appendix B of LS107-03.0. Safety features include thefollowing:

¥ control panel labels with the words “CAUTION—THISEQUIPMENT PRODUCES X-RAYS WHEN ENERGIZED,”

¥ fail-safe lights with the words “X-RAYS ON” near x-ray tubehousings,

¥ fail-safe indicators with the words “SHUTTER OPEN” for beamshutters,

¥ fail-safe interlocks on access doors and panels,

¥ beam stops or other barriers, and

¥ appropriate shielding.



Intentional Analytical X-Ray Devices—continued

Enclosed-Beam System

In an enclosed-beam system, all possible x-ray paths (primary anddiffracted) are completely enclosed so that no part of a human bodycan be exposed to the beam during normal operation. Because it issafer, the enclosed-beam system should be selected over theopen-beam system whenever possible.

The x-ray tube, sample, detector, and analyzing crystal (if used)must be enclosed in a chamber or coupled chambers. The samplechamber door must have a fail-safe interlock so that no part of thebody can enter the chamber during normal operation or a shutter inthe primary beam.

The dose rate measured at 2 inches (5 cm) from the outer surfaceof the sample chamber must not exceed 0.25 mrem per hour duringnormal operation.

Open-Beam System

In an open-beam system, one or more x-ray beams are notenclosed, making exposure of human body parts possible duringnormal operation. The open-beam system is acceptable for useonly if an enclosed-beam system is impractical for any of thefollowing reasons:

¥ a need for making adjustments with the x-ray beam energized,

¥ a need for frequent changes of attachments and configurations,

¥ motion of specimen and detector over wide angular limits, or

¥ the examination of large or bulky samples.

A open-beam x-ray system must have a guard or interlock toprevent entry of any part of the body into the primary beam. Eachport of the x-ray tube housing must have a beam shutter with aconspicuous shutter-open indicator of fail-safe design.

The dose rate at 2 inches (5 cm) from the surface of the sourcehousing must not exceed 2.5 mrem per hour during normaloperation.



Intentional Industrial X-Ray Devices

Industrial X-Ray Devices

Industrial x-ray devices are used for radiography, for example, totake pictures of the inside of an object as in a medical chest x-rayor to measure the thickness of material. ANSI N43.3 defines fiveclasses of industrial x-ray installations: cabinet, exempt shielded,shielded, unattended, and open.

Safety requirements and features for industrial installations dependon the magnitude of the hazard and are detailed in Appendix A ofLS107-03.0. Safety features include some or all of the following:

¥ area postings;

¥ control panel caution labels;

¥ surveillance;

¥ barriers or enclosures;

¥ appropriate shielding;

¥ fail-safe interlocks;

¥ visible warning signals such as a rotating beacon;

¥ audible warning signals, 20 seconds before the x-rays areenergized and if an interlock is broken; and

¥ scram switches to de-energize x-rays in an emergency.

Cabinet X-Ray Installation

A cabinet x-ray installation is similar in principle to the analyticalenclosed-beam system. The x-ray tube is installed in an enclosure(cabinet) that contains the object being irradiated, providesshielding, and excludes individuals from its interior during x-rayproduction. An example is the x-ray device used to inspect carry-onbaggage at airline terminals. Certified cabinet x-ray systems complywith the requirements of 21 CFR 1020.40.

The low allowable dose rate of 0.5 mrem per hour at 2 inches(5 cm) from the outside surface of the enclosure for this class ofinstallation necessitates a higher degree of inherent shielding.

The inherent safety of the cabinet x-ray system makes installationpossible in a noncontrolled area.



Intentional Industrial X-Ray Devices—continued

Exempt Shielded Installation

An exempt shielded installation is similar to the cabinet x-rayinstallation. In an exempt shielded installation the source ofradiation and all objects exposed to that source are within anenclosure that excludes individuals from its interior.

The low allowable dose rate of 0.5 mrem per hour at 2 inches(5 cm) from the outside surface of the enclosure for this class ofinstallation necessitates a higher degree of inherent shielding.

An exempt shielded installation does not require occupancyrestrictions because inherent shielding is sufficient.

Shielded Installation

A shielded installation, in which the source of radiation and allobjects exposed to that source are within an enclosure, has lessshielding than an exempt shielded installation. This is a costadvantage for fixed installations, particularly for high-energysources where the reduction in shielding may result in significantsavings. However, there is more reliance on protective measuressuch as warning lights, posting, and procedures.

If the enclosure is large enough to permit entry and exit of workers,visible and audible warning signals are required. Interlocks arerequired to prevent access to the enclosure during x-ray production.A scram switch and suitable means of exit are required so that anyworker who inadvertently remains in the enclosure may leaveimmediately.

The entrance to an exposure room must be posted to alert workersthat they are entering an exposure room. The inside of an exposureroom must be posted according to the radiation level in theenclosure. Occupancy restrictions may be required.



Intentional Industrial X-Ray Devices—continued

Unattended Installation

An unattended installation consists of equipment designed andmanufactured for a specific purpose and does not requirepersonnel in attendance for its operation.

The dose rate at any accessible area 1 foot (30 cm) from theoutside surface of the x-ray device must not exceed 2 mrem perhour or 100 mrem per year.

The low allowable exposure level requires directing the primarybeam away from normally occupied areas and sufficient shielding.Occupancy restrictions are required in the vicinity of the device.

Note: This class of installation is not presently used at LANL.

Open Installation

An open installation has x-ray paths that are not enclosed. Theopen installation is used only when operational requirementsprevent the use of one of the other classes. Its use is limited mainlyto mobile and portable equipment in which fixed shielding cannotbe used. An example is a portable x-ray machine outdoors in anemergency response situation, with the x-ray tube not enclosedinside a shielded room.

An RCT should provide continuous job coverage when an openinstallation is operating.

The protection of personnel and the public depends almost entirelyon strict adherence to SOPs and posting. The x-ray device must bewithin a conspicuous perimeter (rope, tape, or other barrier) that isposted according to the radiation level in the area.

High Radiation Areas, in which the dose rate can exceed 100 mremper hour, must be either locked or under constant surveillance bythe x-ray-device operator to prevent access to the area. Beforeentering the area, the operator must use a radiation monitoringinstrument to detect x-ray production.



Summary of X-Ray Devices

The following table summarizes the classes of x-ray devicesrecognized by ANSI and LANL. For the enclosed beam, exemptshielded, and cabinet systems, access is controlled by enclosingthe x-rays within a chamber or cabinet. The other systems canhave potentially hazardous dose rates outside the system housing,so access must be controlled by a combination of locked doors,posting, warning lights, and procedures.

Summary of X-Ray Devices

Category ofInstallation

Type ofX-Ray Device

MaximumDose Rate

AccessControl

analytical enclosed beam 0.25 mrem/hour chamber

open beam 2.5 mrem/hour beam guard

industrial cabinet 0.5 mrem/hour cabinet

exempt shielded 0.5 mrem/hour cabinet

shielded as posted interlock

unattended 2.0 mrem/hour posting

open as posted surveillance



Self-Assessment

1. An x-ray beam that is purposely generated for a particular useis a (an) ______ system. (EO1)

a. intentional

b. incidental

c. open

d. closed

2. Which of the following is classified as an analytical x-raysystem? (EO2)

a. x-ray diffraction

b. cabinet x-ray

c. industrial

d. radiography

3. An analytical x-ray system in which all possible x-ray paths areconfined within a shielded chamber with interlocks is called a(an) ______ beam. (EO3)

a. shielded

b. enclosed

c. collimated

d. controlled

4. An analytical x-ray system that does not comply with all of therequirements for an enclosed-beam system is classified as a(an) ______ beam system. (EO3)

a. diffracted

b. fluorescent

c. open

d. radiographic

5. The external radiation from a cabinet or an exempt-shieldedx-ray installation must not exceed (EO4)

a. 0.5 mrem per hour at 1 foot

b. 0.5 mrem per hour at 2 inches

c. 5 mrem per hour at 1 foot

d. 5 mrem per hour at 2 inches

✓




6. If the radiation is 150 mrem per hour at 1 foot from an openinstallation, it must be (EO4)

a. closed down

b. shielded with 1.5 mm of lead

c. posted as a High Radiation Area

d. enclosed in a cabinet

7. Generally, x-ray systems require all of the following, except(EO4)

a. warning lights

b. shielding

c. weekly surveys

d. interlocks

✓



Notes . . .



Answers

1. a

2. a

3. b

4. c

5. b

6. c

7. c

Unit 7: Responsibilities for X-Ray Safety


Unit Objectives

Major Objective

Upon completion of this unit, you will understand who is responsiblefor implementing x-ray safety policies and procedures and whattheir specific responsibilities are.



EO1 the responsibilities of the X-Ray Device Control Office,

EO2 the responsibilities of operating groups regarding x-raysafety,

EO3 the responsibilities of x-ray-device custodians, and

EO4 the responsibilities of x-ray-device operators.



Responsibilities

The responsibility for maintaining exposures from x-rays ALARA isshared among the X-Ray Device Control Office, the operatinggroups, x-ray-device custodians, and x-ray-device operators.

X-Ray Device Control Office

The ESH-12 X-Ray Device Control Office (7-8080) is responsiblefor

¥ establishing requirements and standards;

¥ offering consulting services and training;

¥ approving all purchases, moves, transfers, and alterations ofx-ray equipment;

¥ surveying x-ray equipment, verifying that the appropriate safetyprogram requirements have been met, and affixing LANLcompliance labels to the devices; and

¥ issuing variances for devices that do not meet one or more ofthe requirements specified in LS107-03.0, if safety is achievedthrough alternative means or if the function could not beperformed if the device met the requirements.

Operating Groups

Operating groups are responsible for

¥ preparing SOPs and/or HCPs for their x-ray devices;

¥ ensuring that operators know the HCPs and follow SOPs;

¥ authorizing the work and workers, in compliance with LIR300-00-01; and

¥ appointing x-ray-device custodians.



Responsibilities—continued

X-Ray-Device Custodians

X-ray-device custodians are responsible for specific x-ray-generating machines. Their duties include

¥ registering new electron microscopes, intentional x-ray devices,and new x-ray tube assemblies or source housings with theX-Ray Device Control Office;

¥ making arrangements for operator training;

¥ maintaining a list of qualified operators authorized for particularmachines;

¥ documenting that operators have read the appropriate SOPsand HCPs;

¥ posting an authorized operator list near the control panel ofeach x-ray device;

¥ checking enclosure door safety interlocks every six months toensure proper functioning and recording of results on aninterlock test log posted on or near the control panel;

¥ contacting the X-Ray Device Control Office when a device isdue for resurveying and before performing any repair,maintenance, and/or nonroutine work that could cause exposureof any portion of the body to the primary beam; and

¥ meeting all requirements of LIR300-00-01, Safe Work Practices,and Laboratory Procedure (LP) 106-01.0, Lockout/Tagout forControl of Hazardous Energy Sources for Personnel Safety(Red Lock Procedure).

X-Ray-Device Operators

Authorized x-ray-device operators are responsible for

¥ wearing a TLD and other appropriate dosimetry,

¥ knowing the HCP and following the SOP for each machineoperated,

¥ knowing and following the operator safety checklist,

¥ notifying their supervisors of any unsafe or hazardous worksituations, and

¥ before reaching into the primary beam, verifying that the beamshutter is closed or that machine power is off.



Self-Assessment

1. Who must be contacted if alterations are made to an x-raydevice? (EO1)

a. ESH-1

b. ESH-12

c. division director

d. manufacturer

2. Who is responsible for surveying x-ray devices at LANL (EO1)

a. ESH-2

b. ESH-12

c. DX-2

d. none of the above

3. Who is responsible for ensuring that SOPs are prepared forx-ray devices? (EO2)

a. ESH-1

b. ESH-12

c. operating group

d. x-ray-device operator

4. Who appoints the x-ray-device custodian? (EO2)

a. ESH-1

b. ESH-12


d. operating group

5. Who is responsible for checking x-ray-device interlocks? (EO3)

a. ESH-1

b. ESH-12

c. x-ray-device custodian


✓




6. Who is responsible for keeping a list of the authorizedoperators for an x-ray device? (EO3)

a. ESH-1

b. ESH-12

c. x-ray-device custodian


7. Who should be familiar with the SOP for a particular x-raydevice (EO4)

a. ESH-1

b. ES H-12



✓



Answers

1. b

2. b

3. c

4. d

5. c

6. c

7. d

Lessons Learned


Scenario

On April 4, 1974, a worker (worker A) who had been repairing an x-ray spectrometer noticed redness, thickening, and blisters on bothhands. At the medical center, the doctors tried nonspecific anti-inflammatory measures, without effect. Later that month, twocoworkers (workers B and C) noticed similar skin changes, and thetrue nature of the problem became evident.

On March 21, March 29, April 2, and April 4, the three workers hadbeen working to repair a 40-kV, 30-mA x-ray spectrometer. In theabsence of the usual repair people, the three workers were notaware that the warning light was not operating and that the devicewas generating x-rays estimated at 100 R/min. During the work, allthree had received doses of >1,000 R.

By May 9, the acute reactions had largely subsided, but worker Adeveloped a shallow necrotic ulcer on the right index finger andanother on the left ring finger. Over the next few weeks, the ulceron the left ring finger gradually healed, but the right index fingerbecame increasingly painful. In June, three months after the x-rayexposure, the ulcer began to spread, extending up the fingertoward the knuckle. On July 19, the finger was amputated. InAugust, a painful ulcer developed on the left middle finger. Surgerywas performed to sever some nerves, and the finger healedsatisfactorily after a few weeks.

Worker B received a much smaller dose than worker A. Blistersformed during April and completely healed during May. When lastseen, four years after the x-ray exposure, some abnormalities werestill apparent but without any long-term disability.

Worker C was only exposed on April 4. On April 17, he felt aburning pain in and noticed redness on the fingers of both hands.By May 20, these injuries appeared to heal, leaving no apparentdisability. However, in November, a minor injury to his left handdeveloped into an ulcer that appeared to be like the ulcers onpatient A. Worker C’s ulcer healed in December without requiringsurgery.

Lessons Learned


Scenario—continued

In a separate accident on July 26, 1994, a 23-year-old engineerwas repairing a 40-kV, 70-mA x-ray spectrometer. He removedseveral panels and inserted his hand for 5–6 seconds at a distance6-8 cm from the x-ray tube, before realizing that he had failed to de-energize the device.

The engineer recalled having a sensation of tingling and itching inhis fingers the day after the accident. A pinching sensation,swelling, and redness were present between days four and seven.By day seven, a large blister was developing, in addition toincreased swelling and redness. One month after the accident, theentire hand was discolored, painful, and extremely sensitive to theslightest touch. Blood circulation to the entire hand was low,especially to the index and middle fingers. Surgery was performedto sever the sympathetic nerve, so as to allow the constricted bloodvessels to dilate, and a skin graft was sutured in place. One monthlater, the hand had returned to a normal color and the skin graftwas adherent.

In July 1995, one year after the accident, his index finger started toitch and turn black with necrosis or gangrene. As a result, his fingerwas amputated.

Lessons Learned¥ No pain was felt at the time of the x-ray exposure, but

considerable pain was felt later. The injuries took months toheal. In one case, the injuries resulted in permanent disability.

¥ The warning light was not fail-safe. Warning lights must bedesigned so if the light fails, x-ray production ceases.

¥ The workers were not authorized or trained to repair theequipment. They did not analyze the hazards or developcontrols before doing the work. There was no procedure and noRWP.

¥ The workers did not unplug or lockout and tagout theequipment.

Lessons Learned


References

I.J. Weignesberg, C.W. Asbury, and A. Feldman, “Injury Due toAccidental Exposure to X-Rays From An X-Ray FluorescenceSpectrometer,” Health Physics 39, 237-241 (1980).

M.E. Berger et al., “Accidental Radiation Injury to the Hand,” HealthPhysics 72, 343-348 (1997).

Lessons Learned


Notes . . .

Glossary


absorbed dose. The energy imparted to matter by ionizingradiation per unit mass of irradiated material. The unit of absorbeddose is the rad.

accelerator. A device employing an electrostatic orelectromagnetic field to impart kinetic energy to charged molecular,atomic, or subatomic particles that discharges the resultantparticulate or other radiation into another medium and creates aradiological area, due to direct, prompt (beam on) particles or beamradiation and indirect, induced (beam off) radioactivity from beaminteractions with targets and device components, where significantportions of the whole body (as opposed to the extremities) could beexposed.

Examples include linear accelerators (LINACs) such as the LosAlamos Neutron Science Center (LANSCE) accelerator, cyclotrons,synchrotrons, synchrocyclotrons, free-electron lasers (FELs), andion LINACs. Single and tandem Van de Graaff generators, whenused to accelerate charged particles other than electrons, are alsoconsidered accelerators.

Specifically excluded from this definition are devices that accelerateelectrons for the sole purpose of producing x-rays such as someLANL Van de Graaff generators, electron LINACs, the pulsed high-energy machine emitting x-rays (PHERMEX), the dual-axisradiographic hydrotest machine (DARHT), and betatrons used fornondestructive radiographic testing purposes; miscellaneouselectronic devices that produce ionizing radiation as an incidentalbyproduct of their primary function; machines that are incapable ofextracting the beam to a target other than to an x-ray productiontarget and/or that do not produce enough neutrons to cause targetactivation sufficient to create a radiological area in areas normallyoccupied by operating personnel; and machine neutron generators.

access panel. Any barrier or panel that is designed to be removedor opened for maintenance or service purposes, requires tools toopen, and permits access to the interior of the cabinet. See alsodoor, port, and aperture.

access port. See port.

Glossary


analytical x-ray device. A group of local and remote componentsthat use intentionally produced x-rays to evaluate, typically throughx-ray diffraction or fluorescence, the phase state or elementalcomposition of materials. Local components include those that arestruck by x-rays such as the x-ray source housings, beam portsand shutter assemblies, collimators, sample holders, cameras,goniometers, detectors, and shielding. Remote components includepowers supplies, transformers, amplifiers, readout devices, andcontrol panels.

anode. The positive electrode in an x-ray device that emits x-raysafter being struck by energetic electrons from the cathode.

aperture. In this context, the opening within an x-ray sourcehousing that permits the primary x-ray beam to emerge in theintended direction. Such an aperture is not necessarily an openhole, but rather may be a portion of the metal wall of the x-raysource housing that is significantly thinner than the surroundingx-ray source housing walls.

attenuation. The reduction of a radiation quantity upon passage ofthe radiation through matter, resulting from all types of interactionwith that matter. The radiation quantity may be, for example, theparticle fluence rate.

as low as reasonably achievable (ALARA). The operationalradiation protection philosophy of keeping radiation dose as farbelow the occupational dose limits and administrative control levelsas is reasonably achievable so that there is no radiation exposurewithout commensurate benefit based on sound economicprinciples.

bremsstrahlung. The electromagnetic radiation emitted when anelectrically charged subatomic particle such as an electron losesenergy upon being accelerated and deflected by the electric fieldsurrounding an atomic nucleus. In German, the term means brakingradiation.

cabinet x-ray system. An industrial x-ray device with the x-raytube installed in an enclosure (cabinet) that, independent of existingarchitectural structures except the floor upon which it may beplaced, is intended to contain at least that portion of a materialbeing irradiated, provide radiation attenuation, and excludeindividuals from its interior during x-ray generation. Included are allx-ray devices designed primarily for the inspection of carry-onbaggage at airline, railroad, and bus terminals. Excluded from thisdefinition are x-ray devices using a building wall for shielding and

Glossary


those using portable shields on a temporary basis. Certified cabinetx-ray systems shall meet the requirements specified in 21 CFR1020.40.

cathode. The negative electrode that emits electrons in an x-raydevice.

collimator. A device used to limit the size, shape, and direction ofthe primary beam.

compliance label. A LANL label affixed to an intentional x-raydevice certifying that the device has been surveyed and that safeoperating requirements have been met.

control panel. A device containing the means for regulating andactivating x-ray equipment or for preselecting and indicatingoperating factors.

Controlled Area. Any area to which access is managed to protectindividuals from exposure to radiation and/or radioactive materialand which is under the supervision of a person who has knowledgeof the appropriate radiation protection practices, including pertinentregulations, and who has responsibility for applying them.Individuals who enter only the Controlled Area, without enteringradiological areas, are not expected to receive a total doseequivalent of more than 100 mrem (0.001 sievert) in a year.

dark current. A current, usually of electrons, that may flow throughan acceleration tube or wave guide from sources other than thecathode of the accelerator. This is an abnormal phenomenon, oftenassociated with poor vacuum conditions or contaminated surfacesin the acceleration region.

door. In this context, any barrier that is designed to be moved oropened for routine operation purposes, does not generally requiretools to open, and permits access to the interior of the cabinet.

dose equivalent. The product of absorbed dose, the quality factor,and any other modifying factors necessary to express, on acommon scale for all ionizing radiations, the dose incurred byexposed persons. The unit of dose equivalent is the rem. (Forradiation protection purposes, the dose equivalent in rem may beconsidered numerically equivalent to the absorbed dose in rad orthe exposure in roentgen.)

dosimeter. A device that measures and indicates radiation dose.

Glossary


electron volt (eV). A unit of energy equal to the energy gained byan electron passing through a potential difference of 1 volt.

enclosed-beam system. An analytical x-ray system in which allpossible x-ray paths (primary as well as diffracted beams) are fullyenclosed.

exempt shielded installation. An industrial x-ray installation inwhich the source of radiation and all objects exposed to that sourceare within a permanent enclosure that meets the requirements of ashielded installation and contains additional shielding such that thedose equivalent rate at any accessible area 2 inches (5 cm) fromthe outside surface of the enclosure shall not exceed 0.5 per hour.Exempt shielded installations shall meet the radiation safetyrequirements specified in Appendix A of LS107-03.0. This class ofinstallation provides the highest degree of inherent safety becausethe protection does not depend on compliance with any operatinglimitations, and does not require occupancy restrictions outsidethe enclosure.

exposure. A measure of the ionization produced in air by x-ray orgamma radiation. It is the sum of the electrical charges of all of theions of one sign produced in air when all electrons liberated byphotons in a volume element of air are completely stopped in theair, divided by the mass of the air in the volume element. The unitof exposure is the roentgen (R).

external surface. An outside surface of a cabinet x-ray system,including the high-voltage generator, doors, access panels, latches,control knobs, and other permanently mounted hardware andincluding the plane across any aperture or port.

fail-safe design. A design in which the failure of any singlecomponent that can be realistically anticipated results in a conditionin which personnel are safe from exposure to radiation. Such adesign may cause beam-port shutters to close, primary transformerelectrical power to be interrupted, or otherwise prevent emergenceof the primary x-ray beam upon failure of the safety or warningdevice.

flash x-ray unit. A radiation-producing device that can producenanosecond bursts of high-intensity x-radiation.

floor. In this context, the underside external surface of the cabinet.

fluorescence analysis. Analysis of characteristic x-rays and thex-ray emission process.

Glossary


gauge. A device that produces ionizing radiation for the purposeof measuring particular properties of a system.

half-value layer (HVL). The thickness of a specified substancethat, when introduced into a beam of radiation, reduces theexposure rate by one-half.

hazard control plan (HCP). A document that, at a minimum,defines the work, identifies the hazards associated with the work,and describes the controls needed to reduce the risk to anacceptable level, as defined in LIR300-00-01.0.

High Radiation Area. Any area accessible to individuals, in whichradiation is present at such levels that a major portion of the wholebody (whole body, head and trunk, active blood-forming organs,gonads) could receive per hour a deep-dose equivalent in excessof 100 mrem but less than or equal to 500 rad at 1 foot (30 cm)from the radiation source or from any surface that the radiationpenetrates.

incidental x-ray device. A device that emits or produces x-raysin the process of its normal operation, in which the x-rays are anunwanted byproduct of the device’s intended purpose. Examplesinclude video display terminals, electron microscopes, high-voltageelectron guns, electron beam welders, ion implant devices,microwave cavities used as beam guides, radio-frequency cavities,microwave generators (magnetrons/klystrons), and field-emissionelectron beam diodes.

installation. A radiation source, with its associated equipment,and the space in which it is located.

installation enclosure. The portion of an x-ray installation thatclearly defines the transition from a noncontrolled to a controlledarea and provides such shielding as may be required to limit thedose rate in the noncontrolled area during normal operations.

intentional x-ray device. A device in which electrons, which areeither derived from a heated cathode by thermionic emission ordrawn from a cathode tip by a high electric field, undergoacceleration in a vacuum by means of a high electrostatic field(such as conventional x-ray tubes, field emission units, or electronVan de Graaff generators); a high magnetic field (such as abetatron); or an oscillating electric field (such as an electron LINAC)and collide with a metal anode target designed to produce x-raysfor a particular application, generally involving a radiographicprocedure, for which x-rays are essential to the process.

Glossary


Examples include diagnostic medical/dental x-ray devices; electronLINACs used in radiation therapy applications; portable and fixedflash x-ray systems; x-ray diffraction and fluorescence analysisequipment; cabinet x-ray systems; and Van de Graaff generators,electron LINACs, and betatrons used solely to produce x-rays thatdo not produce a sufficient number of neutrons to cause targetactivation sufficient to create a radiological area in areas normallyoccupied by operating personnel.

Specifically excluded from this definition are FELs in which theinitial electrons are produced by a laser beam impinging on aphotocathode.

interlock. A device for precluding access to an area of radiationhazard either by preventing entry or by automatically removing thehazard when the device is actuated.

ion. An atomic particle, atom, or chemical radical bearing anelectric charge, either negative or positive.

ionizing radiation. Any electromagnetic or particulate radiationcapable of producing ions, directly or indirectly, by interaction withmatter, including gamma and x-rays and alpha, beta, and neutronparticles.

lead equivalent. The thickness of lead affording the sameattenuation, under specific conditions, as the material in use.

leakage radiation. Any radiation, except the useful beam, comingfrom the x-ray assembly or sealed source housing.

maximum permissible dose equivalent (MPDE). The maximumdose equivalent that the body of a person or specific parts thereofshall be permitted to receive in a stated period of time.

medical x-ray system. An x-ray system for medical use, generallycategorized as either diagnostic or therapeutic. Diagnostic x-rayprocedures are used to obtain images of body parts; therapeuticx-ray procedures are used to manage malignancies.

normal operation. Operation under conditions suitable forcollecting data as recommended by a manufacturer of the x-raysystem. Recommended shielding and interlocks shall be in placeand operable.

Glossary


occupancy factor. The factor by which the workload should bemultiplied to correct for the degree or type of occupancy of the areaspecified.

occupied area. An area that may be occupied by persons.

open-beam system. An analytical x-ray system in which one ormore x-ray paths (primary as well as secondary) are not fullyenclosed.

open installation. An industrial x-ray installation that, because ofoperational requirements or temporary needs, cannot be providedwith the inherent degree of protection specified for other classes ofindustrial installations. Its use should be limited mainly to mobileand portable equipment where fixed shielding cannot be used. Theprotection of personnel and the public depends almost entirely onstrict adherence to safe operating procedures.

port. In this context, an opening, on the outside surface of thecabinet, designed to remain open during x-ray generation for thepurpose of moving material to be irradiated into and out of thecabinet, or for partial insertion of an object that will not fit insidethe cabinet.

primary beam. The x-radiation emitted directly from the target andpassing through the window of the x-ray tube.

primary radiation. Radiation coming directly from the target of thex-ray tube or from the sealed source.

qualified expert. A person having the knowledge and trainingnecessary to measure ionizing radiation, to analyze the significanceand evaluate the potential health effects, and to advise regardingradiation protection. Examples of persons considered to bequalified experts are those having experience in the industrial usesof radiation and certified by the American Board of Health Physics,the American Board of Industrial Hygiene, the American Board ofRadiology, and/or the American Board of Medical Physics.

quality factor. An energy-dependent dimensionless factor bywhich absorbed dose is to be multiplied to obtain, on a commonscale for all ionizing radiations, the magnitude of radiation effectslikely to be incurred by exposed persons. The quality factor for x-rays, gamma rays, and most beta particles is 1.0; the quality factorfor neutrons is assumed to be 10 in the absence of detailedspectral information.

Glossary


rad (radiation absorbed dose). The unit of absorbed dose. Onerad equals 0.01 joule per kilogram (100 ergs per gram).

Radiation Area. Any area accessible to personnel, in which thereexists radiation at such levels that a major portion of the body(whole body, head and truck, active blood-forming organs, gonads)could receive per hour a dose equivalent in excess of 5 mrem or inany 5 consecutive days a dose equivalent in excess of 100 mrem.

radiation-producing device . A device with a reasonable potentialto expose an individual to significantly hazardous levels of ionizingradiation. Specifically excluded are exempt-shielded devices, asdefined by ANSI N43.3, and devices that do not have a reasonablepotential to expose an individual to more than 100 mrem per year ofwhole-body dose, or 1 rem per year extremity dose.

radiation protection survey. An evaluation of the radiation hazardpotential in and around an x-ray installation. It customarily includesa physical survey of the arrangement and use of the equipment andmeasurements of the exposure rates under expected or routineequipment operating conditions.

radiation source. A device or a material that is capable of emittingionizing radiation.

radiological worker. A general employee whose job assignmentinvolves operating radiation-producing devices or working withradioactive materials, or who is likely to be routinely occupationallyexposed above 0.1 rem per year total effective dose equivalent.(10 CFR 835)

radiological control technician (RCT). Any person who is activelyengaged in or who has completed core RCT training, site-specificRCT training, standards and procedures training, a comprehensivewritten examination, and an oral board, as specified in the LANLRadiological Control Manual.

rem (roentgen equivalent man). The unit of dose equivalenceused to measure human exposures, which considers the biologicaleffects of different types of radiation. The dose equivalent in rem isnumerically equal to the absorbed dose in rad multiplied by thequality factor and any other necessary modifying factors.

roentgen (R). The unit of exposure. One roentgen equals2.58 x 10-4 coulomb per kilogram of air.

Glossary


scattered radiation. Radiation that has been deviated in directionas a result of interaction with matter and has usually been reducedin energy.

secondary radiation. Radiation (electrons, x-rays, gamma rays,or neutrons) produced by the interaction of primary radiation withmatter.

shielding. Attenuating material used to reduce the transmissionof radiation. The two general types of shielding are primary andsecondary. Primary shielding is material sufficient to attenuate theuseful beam to the required level. Secondary shielding is materialsufficient to attenuate stray radiation to the required level.

shielded installation. An industrial x-ray installation in which thesource of radiation and all objects exposed to that source are withina permanent enclosure. The dose equivalent rate at any accessiblenoncontrolled area 1 foot from the outside surface of the shieldedenclosure shall not exceed 2 mrem per hour. Shielded installationsshall have interlocks and visible and/or audible warning signals asspecified in Appendix A of LS107-03.0. This class of installationusually offers the greatest cost advantage for fixed installations.

skyshine. Radiation emerging from a shielded enclosure whichthen scatters off air molecules to increase radiation levels at somedistance from the outside of the shield.

stem radiation. X-rays given off from parts of the anode other thanthe target, particularly from the target support.

stray radiation. Radiation other than the useful beam. It includesleakage and scattered radiation.

system barrier. The portion of an x-ray installation that clearlydefines the transition from a Controlled Area to a Radiation Areaand provides such shielding as may be required to limit the doserate in the Controlled Area during normal operation.

tenth-value layer (TVL). The thickness of a specified substancethat, when introduced into a beam of radiation, reduces theexposure rate to one-tenth of the original value. One TVL isequivalent to 3.3 HVLs.

unattended installation. An industrial installation, as specifiedin LS107-03.0, that consists of equipment designed andmanufactured for a specific purpose and that does not requirepersonnel in attendance for its operation. The inherent radiation

Glossary


safety of such equipment may make installation possible in anoncontrolled area.

units. Systeme Internationale (SI) units used for quantities that arenot unique to ionizing radiation measurements such as energy perunit mass, that is, joules/kilogram; 1 J/kg = 1 gray. Conventionalspecial radiation units are units used for quantities unique toionizing radiation measurement such as the rad, rem, androentgen. To convert conventional radiation units to SI units, thefollowing factors are used:

1 rad = 0.01 gray (Gy)1 rem = 0.01 sievert (Sv)

1 roentgen (R) = 2.58 × 10-4 coulomb per kilogram of air

use factor. The fraction of the workload during which the usefulbeam is pointed in the direction under consideration.

useful beam. The part of the primary and secondary radiationthat passes through the aperture, cone, or other device used forcollimation.

Very High Radiation Area. Any area accessible to individuals inwhich radiation is present at such levels that a major portion of thewhole body (whole body, head and truck, active blood-formingorgans, gonads) could receive per hour an absorbed dose inexcess of 500 rad (5 gray) at 1 meter from the radiation sourceor from any surface that the radiation penetrates.

warning label. A LANL label affixed to the x-ray device warningthat the device must not be used.

workload. A measure, in suitable units, of the amount of use ofradiation equipment. For the purpose of this document, theworkload is expressed in milliampere-minutes per week for x-raysources, and roentgens per week at 1 meter from the source forgamma-ray sources and high-energy equipment (such as linearaccelerators, betatrons, etc.).

x-ray accessory apparatus. Any portion of an x-ray installationthat is external to the radiation source housing and into whichan x-ray beam is directed for making x-ray measurements or forother uses.

Glossary


X-Ray Device Control Office. A team in the Policy and ProgramAnalysis Group (ESH-12) that establishes x-ray-device programrequirements and standards, provides x-ray-device radiationprotection consultation, and serves as the central LANL point ofcontact for the management/control of x-ray devices as mandatedby the DOE.

x-ray-device custodian. A person designated by line managementas responsible for specific x-ray devices. This individual isresponsible for designating the operators of specific x-ray devices,arranging for the operators to attend x-ray safety training, assistingin the compilation/maintenance of the x-ray-device SOP,familiarizing operators with the x-ray-device SOP, maintainingrecords of operator training and safety interlock checks, serving asthe point of contact for the line organization’s x-ray devices, andcoordinating surveys with the X-Ray Device Control Office. Anx-ray-device custodian may also be an x-ray-device operator.

x-ray-device operator. An individual designated in writing by thex-ray-device custodian and qualified by training and experience tooperate a specific x-ray device.

x-ray diffraction. The scattering of x-rays by matter withaccompanying variation in intensity in different directions due tointerference effects.

x-ray installation. One or more x-ray systems, the surroundingroom or controlled area, and the installation enclosure.

x-ray power supply. The portion of an x-ray device that generatesthe accelerating voltage and current for the x-ray tube.

x-ray source housing. An enclosure directly surrounding an x-raytube that provides attenuation of the radiation emitted by the x-raytube. The x-ray source housing typically has an aperture throughwhich the useful beam is transmitted.

x-ray system. An assemblage of components for the controlledgeneration of x-rays.

x-ray tube. An electron tube that is designed for the conversion ofelectrical energy to x-ray energy.

x-ray tube assembly. An array of components typically containingthe cathode, anode, x-ray target, and electron-acceleratingcomponents within a vacuum.

Glossary


Notes . . .

References


“American National Standard for General RadiationSafety—Installations Using Non-Medical X-Ray and SealedGamma-Ray Sources, Energies up to 10 MeV,” ANSI N43.3,American National Standards Institute, 1993.

“Occupational Radiation Protection,” Title 10, Code of FederalRegulations, Part 835 (most recent edition).

“Radiation Generating Devices,” Implementation Guide for Use withTitle 10, Code of Federal Regulations, Part 835, “OccupationalRadiation Protection,” November 1994.

“Radiation Safety for X-Ray Diffraction and Fluorescence AnalysisEquipment,” ANSI N43.2, American National Standards Institute,1977 (reaffirmed 1989).

“Radiation Safety Training Criteria for Industrial Radiography,”NCRP Report, No. 61, National Council on Radiation Protectionand Measurements, 1978.

Radiological Control Manual, DOE/EH-0256T, Revision 1,Department of Energy, April 1994.

“Radiological Protection Training,” Implementation Guide for Usewith Title 10, Code of Federal Regulations, Part 835, “OccupationalRadiation Protection,” November 1994.

“X-Ray Generating Devices,” LS107-03.0, Los Alamos NationalLaboratory, October 1994.

References


Notes . . .

Appendix A


Radiation Safety Requirements for Industrial X-Ray Devices(LS107-03.0)

This appendix outlines the safety requirements for the design, installation, andoperation of industrial (nonanalytical) x-ray installations at the Laboratory.Electrical safety guidelines or considerations other than radiation safety are notincluded.

Radiation facilities shall be constructed to meet the requirements of one of theclasses of installations described below. The classes differ in their relativedependence on inherent shielding, operating restrictions, and supervision toensure the required degree of protection.

Shielded Installation. Assuming the x-ray device is located in an enclosure thatis large enough to permit entry and exit of personnel, shielded installations mustbe equipped with one of the following interlock/warning signal systems,depending on the primary beam radiation exposure rate of the x-ray device.

Option 1. Use this option for x-ray devices capable of producing a HighRadiation Area (greater than 100 mR/hr in the primary x-ray beam measured1 foot away from the x-ray tube anode) but not a Very High Radiation Area. Allaccess doors that open into the enclosure must have one fail-safe interlock pereach door and either a visible or an audible warning signal inside the enclosure.

• Visible Warning Signal. If a visible warning signal is provided, typically, arotating beacon-type device, such a signal must actuate whenever the primarybeam radiation exposure rate exceeds 100 mR/hr and, once actuated, mustremain actuated throughout the remainder of the radiation exposure time.

• Audible Warning Signal. If an audible warning signal is provided, this devicemust activate whenever an interlocked enclosure door is opened and theprimary x-ray beam radiation exposure rate exceeds 100 mR/hr at a distance of1 foot from the x-ray-tube anode. The audible signal must produce a frequencyand sound pressure level sufficient to be clearly audible to both the x-ray-device operator and any other person attempting to enter the radiation exposurearea through any of the interlocked doors. The audible signal should producean overall sound pressure level that is not less than 10 dB above the overallmaximum typical ambient noise level, and in any case, not less than 75 dB(referenced to 20 µN/m 2 ) at every location from which immediate evacuationis deemed essential. The audible warning signal need not remain on during theentire exposure period.

Introduction

Classes ofInstallations

Appendix A


Radiation Safety Requirements for Industrial X-Ray Devices(LS107-03.0)—continued

Option 2. Instead of Option 1, described above, all access doors that open intothe enclosure shall have a minimum of two interlocks wired in series, any one ofwhich shall be such that opening the door results in a physical disconnection ofthe energy supply circuit to the high-voltage generator. This disconnection shallnot depend on any moving part other than the door.

• For x-ray devices capable of producing a Very High Radiation Area (greaterthan 500 R/hr [500,000 mR/hr] in the primary x-ray beam measured at onemeter [equivalent to greater than 8.3 R/minute]), all access doors that open intothe radiation enclosure must have at least one fail-safe interlock and both anaudible and a visible warning signal. Both signals must actuate a minimum of20 seconds immediately before irradiation can be started, and the visible signalmust remain on throughout the entire radiation exposure time. The audiblesignal need not remain on during the entire exposure period, but must beactuated if any interlocked enclosure access door is opened and the primaryx-ray beam radiation exposure rate exceeds 100 mR/hr at a distance of 1 footfrom the x-ray tube anode.

• Whenever the enclosure (room) is large enough that it might take severalseconds for a person to exit the room in the event that the 20-second warningsignals are activated, at least one clearly labeled, emergency off (scram) switchmust be located inside the radiation enclosure. Once the scram switch ispressed, irradiation shall not be able to be resumed unless the switch is resetand the x-ray-device control panel is also reset.

• The outside area of entrances to the radiation enclosure shall be posted with asign that is illuminated when the 20-second warning signals, specified above,are activated. Such a sign should display the radiation symbol and the wordsDANGER—VERY HIGH RADIATION AREA INSIDE, or words ofequivalent meaning. The interior of the radiation enclosure shall be posted withpermanent signs that display the radiation symbol and the wordsDANGER—VERY HIGH RADIATION AREA, or words of equivalentmeaning. There must be enough interior signs that at least one sign will bereadily visible when any interlocked access door to the radiation enclosure isopened.

• The exterior surface of radiation enclosure access doors shall be posted with asign displaying the radiation symbol and the words CAUTION—ENTERINGA RADIATION EXPOSURE ROOM—RADIATION SURVEYINSTRUMENT REQUIRED, or words of equivalent meaning, as well as witha sign displaying the radiation symbol and the words CAUTION—X-RAYS.

Classes ofInstallations—continued

Appendix A



• The dose equivalent rate at any accessible noncontrolled area, 1 foot (30 cm)from the outside surface of the radiation enclosure (shielding), shall not exceed2 mrems in any 1 hour. Measurements for compliance to this limit may beaveraged over a cross-sectional area of 10 cm 2 . This dose equivalent rateshall be measured with the x-ray device operating at the maximum beamcurrent and voltage for continuous operation. No radiation-beam-limiting or -collimating devices or added beam filters shall be used during such shieldingevaluation measurements unless such devices/filters are integral to andpermanently fixed components of the x-ray device. The radiation beam shall bepositioned and oriented so that the highest exposure rate will be encountered inthe area under evaluation, provided that such positioning and orientation willserve a practical purpose in normal use.

Exempt Shielded Installation. To be classified as an exempt shieldedinstallation, such an installation must meet all of the above requirements for ashielded installation and contain additional radiation shielding, such that the doseequivalent rate at any accessible region 2 inches (5 cm) from the outside surfaceof the radiation enclosure under maximum credible operating parameters doesnot exceed 0.5 mrem in any 1 hour. This limit ensures with reasonableprobability that under practical conditions of occupancy and use, no one, eitherwithin the controlled area or in the environs of the installation, is exposed tomore radiation than that allowed by the radiation protection standards specifiedin Administrative Requirement 3-2, "Radiation Protection Exposure Standards.”Exempt shielded installations do not require any personnel occupancy controlsoutside the enclosure.

Cabinet X-Ray Systems. Cabinet x-ray systems certified under the provisionsof 21 CFR 1020.40 shall comply with the requirements of exempt shieldedinstallations.

Unattended Installation. Design of such installations shall ensure thatindividuals in the area are not exposed to a dose equivalent rate in excess of100 mrems/year from operation of the shielded, single-purpose x-ray device orgauge. This may be achieved by orienting the primary beam in a direction awayfrom normally occupied areas, by sufficient shielding of the x-ray tube, and byadministrative measures. On or near such installations, warning signs with thewords CAUTION—X-RAYS shall be posted.

• Unattended Gauge Installation. Gauging devices in which it is possible to insertany part of the body into the primary radiation beam shall be posted with awarning sign(s) alerting individuals to the presence of radiation within the airgap. Such sign(s) shall be visible from the normal avenues of approach to thegauging device.


Appendix A



• Unattended Nongauge Installation. If the device is equipped with a shutter orother absorber so that the primary radiation beam can be reduced in magnitude,the "closed” and "open” position shall be easily identified. X-ray machinesshall have a visual warning signal when x-rays are produced that is visibleto individuals approaching the x-ray beam. The dose equivalent rate at anyaccessible area 1 foot (30 cm) from the outside surface of the device shall notexceed 2 mrems in any 1 hour when the device is in its normal operatingcondition. Occupancy in the vicinity of the x-ray device shall be limited sothat the dose equivalent rate to an individual in any one year shall not exceed100 mrems. Access panels opening into areas with exposure levels in excessof 2 mrems in any 1 hour shall be locked or secured with tamper resistantfasteners.

Open Installation. Such installations are ones that, because of operationalrequirements or temporary needs, cannot be provided with the inherent degreeof protection specified for either the shielded, exempt shielded, or unattendedinstallations. Open installations are limited mainly to mobile and portable x-raydevices in which permanent shielding cannot be used. For such installations,adequate radiation safety for the installation operators and the public dependsalmost entirely on strict adherence to SOPs (administrative controls). An openinstallation shall be approved by the Policy and Program Analysis Group(ESH-12) only in situations in which the use of one of the other classes is notfeasible. Open installations shall conform to all of the following requirements:

• The radiation source and all objects exposed thereto shall be located at theapproximate center of two roughly concentric perimeters. The innermostperimeter, delineated by rope, tape, or other suitable material, will be theoutermost boundary of the High Radiation Area inside of which the doseequivalent rate can exceed 100 mrems in any 1 hour. The outermost perimeterwill be the boundary outside of which the dose equivalent rate does not exceed5 mrems in 1 hour, and inside of which constitutes a Radiation Area. Both ofthese perimeters shall be posted with appropriate radiation warning signs inaccordance with LS107-02.2, “Radiological Posting.”

• The High Radiation Area shall be kept under constant surveillance by a trainedoperator who is knowledgeable in the safe operation of the source and who willprevent access to areas in excess of 100 mrems in any 1 hour. No person shallremain within the High Radiation Area during irradiation.

• The radiation source and equipment essential to the use of the source shall beinaccessible to unauthorized use, tampering, or removal. This shall beaccomplished by the attendance of a qualified operator or by other positivemeans such as locked enclosures.


Appendix A



• When entering an open installation after using the x-ray device, the operatorshall use a suitable survey meter and/or chirper, as determined by the HealthPhysics Operations Group (ESH-1), to verify that x-rays are no longer beingproduced.

In addition to the compliance labels specified in section 7.6, the x-ray-devicecustodian shall ensure that the x-ray-device control panel displays a label statingthat the X-Ray Device Control Office shall be notified when the x-ray device isto be moved, transferred, or altered. For x-ray devices, the system control panelshall also have a legible label bearing the conventional radiation symbol andwords CAUTION—THIS EQUIPMENT PRODUCES X-RAYS WHENENERGIZED, or words of equivalent meaning.


Control PanelLabels

Appendix A


Notes . . .

Appendix B


Radiation Safety Requirements for Analytical X-Ray Devices(LS107-03.0)

This appendix outlines the safety requirements for the design, installation,and operation of x-ray diffraction and x-ray fluorescence equipment at theLaboratory. In addition, radiation safety guidance is provided for electronmicroscopes. Electrical safety guidelines or considerations other than radiationsafety are not included.

For x-ray diffraction and x-ray-fluorescence equipment, in addition to thecompliance labels specified in section 7.6, the custodians of such devices shallensure that the x-ray-device control panel displays a label stating that the X-RayDevice Control Office shall be notified when the device is to be moved,transferred, or altered. The device control panel shall also have a legible labelbearing the conventional radiation symbol and words CAUTION—THISEQUIPMENT PRODUCES X-RAYS WHEN ENERGIZED, or words ofequivalent meaning.

Any access panel with significant exposure rates behind it (as determined bythe X-Ray Device Control Office) must have a safety interlock. The maximumexposure rate during any phase of operation of an electron microscope (at themaximum-rated continuous-beam current for the maximum-rated acceleratingpotential) must not exceed 0.5 mR/hour at a distance of 2 inches (5 cm) from anyaccessible external surface, including column, high-voltage cable, high-voltagetank, console, and power supply cabinet.

Common Provisions. Some fail-safe features have been incorporated intoexisting x-ray diffraction and fluorescence analysis systems. In a fail-safe design,failures of indicator or safety components (that can reasonably be anticipated)cause the equipment to fail only in modes that are guaranteed to prevent theexposure of individuals to radiation. For example, if a light indicating X-RAYSON fails, the production of x-rays is automatically prevented; or, if a shutterstatus indicator fails, the shutter automatically closes.

Special accessories to the equipment (for example, a powder-diffraction camera)must include a beam stop or other barrier so that the exposure rate caused by thetransmitted primary beam does not exceed 0.25 mR/hour under normal operatingconditions.

Introduction

Control PanelLabeling

ElectronMicroscopes

X-Ray Diffractionand FluorescenceAnalysis Equipment

Appendix B


Radiation Safety Requirements for Analytical X-Ray Devices(LS107-03.0)—continued

Fail-safe warning lights or indicators labeled with the words X-RAYS ON, orwords with similar meaning, must be installed in a conspicuous location near thex-ray tube housing to indicate when the x-ray tube is on. These indicators are tobe energized automatically and only when the tube current flows or high voltageis applied to the x-ray tube.

Common Safeguards. Before removing the tube housings or modifying shutters,collimators, or beam stops, the operator shall ensure that proper lockout/tagoutprocedures are followed at the source of electrical power and that the x-raydevice is off and remains off until safe conditions have been restored. The mainpower switch, rather than safety interlocks, must be used for routine shutdownin preparation for repairs.

Whenever manufacturer’s alignment procedures are available, prescribedsafeguards must be followed. The manufacturer’s recommended safetyprocedures must not be modified without approval from the user’s group leader.If an alignment procedure can cause an increased exposure rate in any area, theX-Ray Device Control Office must be notified, and the operator shall erecttemporary barriers and warning signs, as required by that office. The operatormust keep the area under surveillance until normal operation has been restored.Safety glasses (with glass lenses only) shall be used during open-beam alignmentprocedures to protect the eyes from an accidental primary beam exposure.

Open-Beam Systems. In addition to the safeguards described above, shutters inan open-beam system must be provided with a conspicuous SHUTTER OPENindicator of fail-safe design.

A guard or interlock that prevents entry of any part of the body into the primarybeam must be provided. Each port of the x-ray tube housing must be providedwith a beam shutter. Whenever an accessory setup is not permanent (that is,subject to frequent or periodic change), the shutter must be interlocked withevery accessory apparatus coupling or collimator so that the port will be openonly when the collimator or coupling is in place. Shutters at unused ports mustbe secured (e.g., bolted shut or interlocked) to prevent casual opening.

The exposure rate external to the x-ray-source housing, with all shutters closed,must not exceed 2.5 mR/hour as measured 2 inches (5 cm) from the surface ofthe housing within which the x-ray-tube assembly is operating at maximumaccelerating voltage and maximum continuous-tube milliamperage. Lead foiland/or portable shields shall be used whenever necessary to reduce scatter orother secondary radiation to this level.

Enclosed-Beam Systems. The radiation leakage limit for an enclosed beamsystem at 2 inches (5 cm) from outer surfaces of the sample chamber wall shallnot exceed 0.25 mR/hour during normal operation.

X-Ray Diffractionand FluorescenceAnalysis Equipment—continued

Appendix B


Radiation Safety Requirements for Analytical X-Ray Devices(LS107-03.0)—continued

The x-ray tube, sample, detector, and analyzing crystal (if used) must beenclosed in a chamber or coupled chambers that cannot be entered by any part ofthe body during normal operation. The sample chamber door or other closuremust befail-safe interlocked to the x-ray tube high-voltage supply or have a shutter inthe primary beam so that no x-ray beam can enter the sample chamber while theshutter is open.

Selection of Open- or Enclosed-Beam System. An enclosed-beam systemshall be selected over an open-beam system whenever feasible. An open-beamsystem is only approved if an enclosed-beam system is impractical because ofoperational requirements such as the following:• a need for frequent changes of attachments and configurations,• motion of specimen and detector over-wide angular limits, or• examination of large or bulky samples.

X-Ray Diffractionand FluorescenceAnalysis Equipment—continued

Appendix B


Notes . . .

Final Quiz

To receive credit for this self-study, you must complete the final quiz. The final quiz is located inthe Training Validation System (TVS).

Caution

• You need a SecureID or Crypto Card that is assigned to you and Administrative Access tothe Lab’s Integrated Computing Network (ICN) to complete the final quiz.

If you do not have a SecureID or Crypto Card that is assigned to you and ICNAdministrative Access, you must complete the final quiz at the ES&H Training Center inWhite Rock.

To schedule a time to complete the final quiz, contact the ESH-13 Registrar either by phoneat 7-0059 between 8:00 am and 5:00 pm or by e-mail at [email protected].

• Do not complete the final quiz using another person’s SecureID or Crypto Card. You canonly receive credit for the final quiz using a SecureID or Crypto Card that is assigned to you.

Starting the Quiz

To start the final quiz, click the Start Quiz button below:

Troubleshooting

• Acrobat Reader for Windows displays error “A Web browser has not been specified. Do youwant to configure the Weblink preferences?”

• Acrobat Reader for Macintosh displays “Select Web Browser” dialog box.

• Clicking Start Quiz button doesn’t bring up Netscape Navigator and/or get error message“The Web browser has not responded to your request for one minute: Terminating request.”.

• You get an error message after submitting the TVS quiz.

• Other problems: Contact CIC-6 Customer Server at 5-4444.

Acrobat Reader for Windows displays error “A Web browser has not beenspecified. Do you want to configure the Weblink preferences?”

If you are using a Windows PC, you may see the error message below when you click the Start Quizbutton:

This message appears when a Web browser has not been selected in the Acrobat Reader WeblinkPreferences. To select a Web browser, follow the instructions below:

1. Click the Yes button on the Acrobat Weblink error dialog box.Acrobat Reader displays the Weblink Preferences window.

2. Click the Browse… button.Acrobat Reader displays the Locate the Web Browser dialog box.

3. Use the dialog box to find your Web browser program, highlight the program name, and click theOpen button.Acrobat Reader puts the path to the Web browser program you selected into the WWW BrowserApplication text box on the Weblink Preferences window.

4. Click the OK button on the Weblink Preferences window.Acrobat Reader closes the Weblink Preferences window, starts the Web browser you selected, andlinks to TVS.

Note: If you need assistance configuring Adobe Acrobat Reader, contact CIC-6 Customer Service at 5-4444.

Return to Starting the Quiz

Acrobat Reader for Macintosh displ ays “Select Web Br owser” dialo g box

If you are using a Macintosh, you may see the dialog box below when you click the Start Quiz button:

This message appears when a Web browser has not been selected in the Acrobat Reader WeblinkPreferences. To select a Web browser, follow the instructions below:

1. Use the dialog box to find your Web browser program, highlight the program name, and click theOpen button.Acrobat Reader puts the name of the Web browser program you selected into the WWW BrowserApplication text box on the Weblink Preferences window.

2 Click the OK button on the Weblink Preferences window.Acrobat Reader closes the Weblink Preferences window, starts the Web browser you selected, andlinks to TVS.

Note: If you need assistance configuring Adobe Acrobat Reader, contact CIC-6 Customer Service at 5-4444.


The Web browser has not responded to your request for one minute:Terminating request.

If you are using a Macintosh, Adobe Acrobat Reader 3.x, and Netscape Navigator 4.x, you may see thefollowing problems when you click on the Start Quiz button:

• Netscape Navigator will fail to appear and• You see the following error message dialog box:

There is a bug in Adobe Acrobat Reader 3.x that creates these problems. In fact, a Netscape Navigatorwindow is open behind the Acrobat Reader window. You can work around the problem by following theinstructions below:

1. Click the OK button on the error message dialog box.Adobe Acrobat closes the error message dialog box and returns to the document window.

2. Click the Application Menu icon on the Mac OS menu bar.The Mac OS displays the Application Menu.

3 Click Netscape Navigator in the Application Menu.The Mac OS displays the Netscape Navigator window.

Note: If you need further assistance, contact CIC-6 Customer Service at 5-4444.


TVS Error Message After Submitting Quiz

If you receive an error message from TVS after you submit your quiz, please contact JohnConlon at 5-8248 or [email protected] with the following information:

• Your z-number• Your name• Your e-mail address• The approximate time you submitted your quiz• Your IP address (if available)

John will check TVS to see if your quiz was graded and contact you with the results.


NoteAs of Monday, January 24, 2000, you must have the following to complete self-study quizzes in theTraining Validation System (TVS):

• A Secure ID card or CryptoCard that is assigned to you and• Administrative access to the Laboratory’s Integrated Computing Network (ICN).

If you only have Open access to ICN, you will see the following error message:

Authentication failed – Reason: Authentication Server Unavailable

The window you see will look similar to the window below:

If you see the page above when you try to authenticate, you can

• Schedule a time to come to the ES&H Training Center in White Rock to complete the final self-study quiz or

• Request Administrative access to ICN by obtaining a copy of the ICN Access AuthorizationPacket and following the instuctions in the packet.

To schedule a time to complete the final quiz, contact the ESH-13 Registrar either by phone at 7-0059between 8:00 am and 5:00 pm or by e-mail at [email protected].

We apologize for any inconvenience this change in secur ity might cause.

https://tvprod.lanl.gov/pb/Pbisa050.dll/tv_server/tv/of_generate?ls_subject=72+&ls_validate=Quiz+Validate+Student&ls_type=Quiz&ls_tst_grp=Environmental+Safety+and+Health&ls_proct_auth=none

Date post:	06-Feb-2018
Category:	Documents
Upload:	doandiep
View:	216 times
Download:	2 times