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Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

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Nuclear Power and Public Nuclear Power and Public Health Measures in Health Measures in Nuclear Plant Emergencies Nuclear Plant Emergencies reac/ts reac/ts R. E. Toohey, Ph.D., CHP
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Page 1: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Nuclear Power and Public Nuclear Power and Public Health Measures in Health Measures in

Nuclear Plant EmergenciesNuclear Plant Emergencies

reac/tsreac/ts

R. E. Toohey, Ph.D., CHP

Page 2: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Lesson ObjectivesLesson Objectives

Familiarize students with the basic characteristics of nuclear power plant accidents

Describe planning guidelines and considerations for accident response

Apply considerations to the accidents at Three Mile Island and Chornobyl

Page 3: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

The Fission ProcessThe Fission Process

Fissile nuclideneutron

neutrons

Fission products

Page 4: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Fission Product Yield by MassFission Product Yield by Mass

Page 5: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Approximate Distribution of Fission Approximate Distribution of Fission EnergyEnergy

MeV

Kinetic energy of fission fragments 165Instantaneous gamma-ray energy 7Kinetic energy of fission neutrons 5Beta particles form fission products 7Gamma rays from fission products 6Neutrinos 10

Total fission energy ∼200

Page 6: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Neutron BalanceNeutron Balance Neutrons released in fission may be lost by escaping

the container, or by being absorbed by non-fissile materials

If more neutrons are lost than are produced, the reaction is subcritical and dies out (“safe”)

If the number lost equals the number produced, the reaction is critical (steady state, e.g., a reactor)

If the fewer neutrons are lost than are produced, the reaction is supercritical and energy release increases exponentially (e.g., a nuclear weapon)

Page 7: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Nuclear Reactor SchematicsNuclear Reactor Schematics

Pressurized Water Nuclear ReactorPressurized Water Nuclear Reactor

Page 8: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Nuclear Reactor SchematicsNuclear Reactor Schematics

Boiling Water Nuclear ReactorBoiling Water Nuclear Reactor

Page 9: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Reactor AccidentsReactor Accidents

Loss of Coolant Accident (LOCA) Pipe breaks in the primary loop remove

cooling water from the core, leading to an increase in core temperature

Fuel rods fail, releasing volatile radionuclides (iodine, cesium, etc.)

Core meltdown—all the way to China?

Page 10: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

What Really HappensWhat Really Happens

Fuel expands, reducing reaction rate Reactor scrams with gravity-induced

lowering of control rods Emergency core cooling system activates

and floods core Even if core does melt, containment

systems works, as at TMI

Page 11: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Reactor AccidentsReactor Accidents

Most likely route of exposure to the public would be a release to the air.

Plume materials could consist of particulates, vapors, mists, or gases.

Plume could be short duration (puff) or continuous.

Particulates will tend to settle to the ground as the plume drifts from the plant.

Page 12: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Atmospheric ReleasesAtmospheric Releases

Volatile radionuclides may be released from containment

Principal radionuclide of concern is 131I Releases are monitored by sensors placed

around plant Plume dispersal is mathematically modeled,

taking local terrain into account

Page 13: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Airborne RadioactivityAirborne Radioactivity “Source term” - source of the exposure

– examples - stack effluent, burning aircraft, etc.– complex function of the material (quantity and

type), flow rate,distribution,etc.– units - activity/unit of time (e.g., Ci/sec; Bq/sec)

Population/personnel exposure– airborne (radioactivity) concentration

[µCi/ml; Bq/m3]– resuspended (ground/surface) contamination

[µCi/ft2; Bq/m2 →µCi/ml; Bq/m3]

Page 14: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies
Page 15: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies
Page 16: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies
Page 17: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Plume DispersionPlume Dispersion

Page 18: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies
Page 19: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Exposure PathwaysExposure Pathways

External dose from plume overhead (cloud shine) or material on ground (ground shine).

Internal dose due to inhaling materials directly from plume or from stirred dust.

Ingestion of contaminated materials in the form of food or water.

Page 20: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Emergency Planning ZoneEmergency Planning Zone

Areas for which planning is needed to assure that prompt and effective actions can be taken to protect the public

Plume EPZ: radius of approximately 10 miles

Ingestion EPZ: radius of approximately 50 miles

Page 21: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Exclusion AreaExclusion Area

An area surrounding the plant such that an individual located at any point on its boundary will not receive a dose to the whole body exceeding 250 mSv (25 rem) nor a dose to the thyroid exceeding 3 Sv (300 rem) within 2 hours of the postulated incident

Page 22: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Classification of EmergenciesClassification of Emergencies

Unusual Event: a potential degradation of the level of safety of the plant

Alert: readiness of on-site and off-site response organizations increased.

Site Area Emergency: event resulting in major decrease in protection of public or on-site personnel.

General Emergency: event resulting in risk requiring implementation of urgent off-site actions.

Page 23: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Who is Responsible for Actions?Who is Responsible for Actions?

Staff at the facility at the time of the accident.

Local officials. National and regional officials.

Page 24: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Accident responseAccident response

Independent of the type of accident:– determine and control hazards to

responders & victims – assess, treat, evacuate victims– implement further control procedures– assess personnel exposures– monitor clean-up– verify clean-up effectiveness

Page 25: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Exposure Guidance for RespondersExposure Guidance for Responders

All activities:– 5 rem TEDE, 15 rem eye, 50 rem organ

Protecting major/valuable property:– 10 rem TEDE, 30 rem eye, 100 rem organ

Life saving or protecting large populations:– 25 rem TEDE, 75 rem eye, 250 rem organ

Exceed latter only on a voluntary basis by persons fully aware of risks involved

Page 26: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Additional Guidance for Additional Guidance for RespondersResponders

Risk of injury in rescue and recovery operations shall be minimized

Risks to responders shall be weighed against benefits to be gained

Rescue actions involving substantial personal risk shall be performed by volunteers

Each individual subjected to emergency dose limits shall be thoroughly briefed

Page 27: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Some More Guidance for Some More Guidance for RespondersResponders

Volunteers above age of 45 preferred TEDE shall not exceed 1 Sv (100 rem) Internal exposure should be minimized Exposure under such conditions should be

limited to once in a lifetime Persons receiving exposures above 250

mSv (25 rem) should avoid procreation for several months

Page 28: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Guidance for Population Guidance for Population Protection: 1st PrincipleProtection: 1st Principle

Intervention to avoid serious prompt health effects should be carried out as a first priority– serious prompt health effects may be

expected in susceptible populations at doses > 1 Gy (100 rad), and in all at doses > 2 Gy (200 rad) (whole-body)

– evacuation is usually the only effective intervention measure in high dose situations

Page 29: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Guidance for Population Guidance for Population Protection: 2nd PrincipleProtection: 2nd Principle

Protective actions to avoid delayed health effects should be initiated when they will produce more good than harm in the affected population– iodine prophylaxis in case of radioiodine

releases– sheltering in place, evacuation, or

temporary relocation

Page 30: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Guidance for Population Guidance for Population Protection: 3rd PrincipleProtection: 3rd Principle

These actions should be introduced and withdrawn at levels that produce a maximum net benefit to the population– guidelines available from USEPA, IAEA,

and IRPA– may well be driven primarily by logistical

considerations (e.g., availability of transport, availability of temporary shelters, etc.)

Page 31: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Protective Actions Protective Actions Available to the PublicAvailable to the Public

Sheltering Evacuation Stable Iodine Prophylaxis Other actions to reduce dose

Page 32: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Guidelines for Protective ActionsGuidelines for Protective Actions

Early phase: initiation of release to about 4 days

Evacuate to avoid TEDE of 1 - 5 rem Shelter in place if equal or greater

protection afforded by doing so Administer KI to prevent thyroid dose of 25

rem

Page 33: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Logistical Requirements for Logistical Requirements for Early Protective ActionsEarly Protective Actions

Sheltering:– Normal emergency services; additional police

Evacuation:– Transportation– Temporary housing (schools, tentage, etc.)– Food and water– Sanitation

Iodine prophylaxis:– KI tablets (or tincture of iodine on skin)

Page 34: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Intermediate Phase PAG’sIntermediate Phase PAG’s

Intermediate phase: source or release is under control, and additional protective actions are being implemented; weeks to months

Relocate to avoid 2 rem TEDE or 100 rem to skin in first year

Apply dose reduction techniques (e.g., decontamination, hot spot removal) if less than 2 rem TEDE anticipated in 1st year

Page 35: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Late Phase PAG’sLate Phase PAG’s

Late phase: recovery phase; site remediation and long-term mitigation; months to years

TEDE not to exceed 0.5 rem in any year after the first

Cumulative dose (TEDE) from all years not to exceed 5 rem

Page 36: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Logistical Requirements forLogistical Requirements forLater Protective ActionsLater Protective Actions

Temporary relocation:– Transportation– Housing & furnishings– Security– Decontamination equipment & waste disposal

Permanent resettlement:– Transportation– Housing & furnishings– Security

Page 37: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Food Chain ConsiderationsFood Chain Considerations

Early times: radioiodine pathway is air to soil to vegetation to cow to milk to man

Late times: cesium and strontium pathways include– air to soil to food plants to man– air to soil to forage plants to food animals to

man– air to water to aquatic vegetation to fish to

man

Page 38: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Action Levels for Foodstuffs for Action Levels for Foodstuffs for General ConsumptionGeneral ConsumptionRadionuclideRadionuclide Action LevelAction Level

89Sr103Ru, 106Ru134Cs,137Cs

131I

1 kBq/kg(30 pCi/g)

90S0.1 kBq/kg(3 pCi/g)

238Pu, 239Pu 241Am

0.01 kBq/kg(0.3 pCi/g)

Page 39: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Action Levels for Milk, Infant Action Levels for Milk, Infant Foods and Drinking WaterFoods and Drinking Water

RadionuclideRadionuclide Action LevelAction Level89Sr

103Ru, 106Ru134Cs,137Cs

1 kBq/kg(30 pCi/g)

90S

131I0.1 kBq/kg(3 pCi/g)

238Pu, 239Pu 241Am

0.001 kBq/kg(0.03 pCi/g)

Page 40: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Logistical Requirements for Logistical Requirements for Control of Food and WaterControl of Food and Water

Monitoring capability Centralized distribution Alternate (distant) sources In case of food shortages, alternate

(higher) action levels should be instituted

Page 41: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Three Mile IslandThree Mile Island

Goldsboro, Pennsylvania

Page 42: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

Three Mile IslandThree Mile Island

Unit 2 feedwater pump tripped at 4:00 a.m. on March 28, 1979

Reactor scrammed 8 seconds later Pressure relief valve stuck open, so ECCS

water lost Pressurizer (only way of controlling water

level and pressure in primary loop) filling up, so high pressure injection pumps shut down

Page 43: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

TMI, con’tTMI, con’t

Core partially uncovered by 6:15 a.m. Site emergency declared at 7:00 a.m. General emergency declared at 7:24 a.m. Radiation levels indicated fuel damage

around 8:00 a.m. Core covered with water by 10:30 a.m.

Page 44: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

TMI, con’tTMI, con’t

State route 441 closed at 12:45 p.m. Everything fairly calm the next day Because of confusion and concern over the

“hydrogen bubble”, evacuation advised for pregnant women and preschool children with 5 miles at 12:30 on March 30

Schools closed and further evacuation planned Supplies of KI shipped in

Page 45: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

TMI, con’tTMI, con’t

NRC did not share info that hydrogen bubble was really not a threat

Many families, including health care providers, left on their own

Schools reopened April 4 5-mile evacuation advisory withdrawn on

April 9 Final clean-up cost was $1E9

Page 46: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

ChernobylChernobyl

Page 47: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

ChernobylChernobyl

Page 48: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

The Chernobyl ExperienceThe Chernobyl Experience I. Evacuation:

– Accident occurred 26 April 1986 at 1:23 am– 49,000 evacuated from Pripyat (3 km from

station) on April 27– 53,000 evacuated from 30-km exclusion zone

over next 10 days

Page 49: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

The Chernobyl ExperienceThe Chernobyl Experience

II. Sheltering:– 270,000 persons remained in controlled area

(10,300 sq. km with 137Cs > 15 Ci/sq. km)– delivery of non-contaminated meat and dairy

products continues– agricultural products monitored for

contamination before release for consumption– slow decontamination of settlements– 5 year external dose about 5 rem

Page 50: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

The Chernobyl ExperienceThe Chernobyl Experience III. Health effects:

– 2 acute trauma fatalities– 237 suspected cases of acute radiation

syndrome– 103 confirmed– 28 prompt fatalities– 10 fatalities during 10-year follow-up– 54 local radiation injuries, 14 severe– 10--50-fold increase in childhood thyroid

cancer

Page 51: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies
Page 52: Nuclear Power and Public Health Measures in Nuclear Plant Emergencies

IAEA ACCIDENT SCALE


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