NUMI

NuMI Internal ReviewJuly 12, 2001Infrastructure:

Radiation SafetyPage 1

Technical Components

NuMI Beamline

Radiation Safety Issues

Radiation Safety Coordinator

Nancy Grossman

FNAL

July 12, 2001

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NuMI Internal ReviewJuly 12, 2001Infrastructure:

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Outline

• Overview

• Gate Locations

• Radiation Safety Monitors/Equipment

• Critical Devices

• Access

• Prompt Radiation

• Groundwater Protection

• Air and Water Monitoring

• Component Activation

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NuMI Internal ReviewJuly 12, 2001Infrastructure:

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Radiation Safety Overview

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Gates & Fences

• Probable location of interlocked gates ( ) and locked fences ( )• Gutter, Pipes• Vacuum pump• RAW water system• Interlocked radiation detector

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Radiation Safety Monitors/Equipment

• Presently envision 3 interlocked detectors

– Upstream shaft area

– Power Supply Room

– Hadron Absorber/Bypass tunnel area

• Frisker, portable survey meter, and radioactivity class meter

(3 sets)

– Near upstream shaft interlocked gate area

– Near downstream bypass tunnel interlocked gate area

– Target Hall horn work area

• 2 stack monitors:

– Pre-Target Hall stack

– Target Hall/Decay Region stack

• MOU with the ES&H Section is being drafted to cover:

– Equipment needed for NuMI

– Air and water monitoring

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Critical Devices

Primary Critical Device: Lambertsons (i:LAM60) in MI extraction

Lambertsons power supply will be turned off Beam will stay in MI and oscillate (off-center) and

probably eventually scrape off on something

Secondary Critical Device: First set of bend magnets (e:HV101)

HV101 power supplies will be turned off

MARS runs show that there are no problems with groundwater or personnel protection in the Pre Target region when one or both critical devices are tripped off and beam is extracted to NuMI.

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NuMI Internal ReviewJuly 12, 2001Infrastructure:

Radiation SafetyPage 7Access

NuMI Beam, No Access:

• Carrier Tunnel, Pre-Target, Target Hall, Decay Tunnel, Hadron Absorber Cavern, Muon Alcoves

NuMI Beam Access:

• Base of Target Hall Shaft

• Power Supply & RAW Rooms

– RAW Room may have locked door.

• Bypass tunnel to some extent (determine final gate location when run and do measurements)

• MINOS Cavern

MI Beam NuMI Access:

• Everywhere but the Carrier Tunnel (and upstream)

• Carrier Tunnel will have a Captured Key (or similar) door.

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NuMI Internal ReviewJuly 12, 2001Infrastructure:

Radiation SafetyPage 8Prompt Radiation

Labyrinth and penetration exit dose rates :– Labyrinth source terms where bulk shielding is present (dark blue text) are not well known (factor of 10)

– MARS simulation of the Target Pile has at least 1 foot less steel on all sides than the present design (yellow shading)– Preliminary MARS14 simulation of the present Target Pile shield design is nearly complete

• MARS14 can more accurately determine the source terms outside of thick shielding (factor of 3?)AccessNormal

(mrem/hr)Accident

(mrem/hr)Accident

(mrem/pulse)Mitigation (possible)

Survey Riser SR-1 (498) 0.15 14765.41 7.79 plugExhaust Air Vent EAV-1 (935) 0.03 2852.87 1.51 (fence)Survey Riser SR-2 (954) 0.03 2852.87 1.51 plugTarget Hall Labyrinth 2.44E-04 24.37 0.013 OKTarget Hall Labyrinth 1.36E-03 - - OKTarget Hall Equipment Door 0.02 2476.83 1.31 OKTarget Hall Equipment Door 0.74 - - OKStripline Penetration (PS Room) 2.77 - - (shield)Raw Penetration 60.80 - - plugSurvey Riser SR-3 (1321) 0.002 - - plugVent EAV-2 0.57 - - fenceVent EAV-3 0.57 - - fenceAbsorber Labyrinth 0.09 - - OKBypass Tunnel 0.08 - - OK

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Groundwater Protection: Primary Beam

• Open apertures and “Autotune” will help keep beam nominal and “clean”

• Enable beam extraction to NuMI only when conditions are nominal (Beam Extraction Permit)

– Magnet currents within nominal limits this pulse

– Limit on beam loss last pulse and integrated beam loss (beam loss monitors, Beam Loss Budget System)

– Interlocked radiation detectors

– “Clean” Main Injector beam

• Detailed simulations (MARS14) of the primary beamline and possible accident and DC (continuous) loss conditions have been studied.

– Magnet power supply regulation levels needed to keep losses minimal are obtainable.

– Strong indication that beam loss monitors (BLM) signals closely track groundwater activation levels.

– Plan to test as much of the Extraction Beam Permit System and Beam Loss Budget System as possible in the P150 line starting this year.

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Groundwater Protection: Primary Beam

Preliminary MARS14 Primary beamline results, accident losses:

RegionWater residency

time (years/days)

Water residency time

(days)

Lost pulses allowed in

residency time Comment

Lined Carrier Pipe GT Accident 8.00000 V105, 0.6%

Lined Carrier Pipe (Interface) Accident 1.50919 V104-2, 30%

Unlined Carrier Pipe Accident 0.00487 V104-2, 13%Pre Target Accident (US) 0.01082 V105, 0.2%Pre Target Accident (Mid) 0.01821 V105, 0.2%Pre Target Accident (Shaft) 0.04618 V105, 0.2%Pre Target Accident (DS) 0.04028 V105, 0.2%

6.65 65616.8614.70

579916693

1.78 204

3.95 178

2920.00 4.E+11

550.85 125

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Groundwater Protection: Primary Beam

Preliminary MARS14 Primary beamline results, normal operation:

– Determine worst loss locations for normal operation

– Leads to power supply regulation (and Main Injector beam) requirements

– With presently envisioned power supply regulation:• All normal (DC) losses in the primary beam region are at least

an order of magnitude below what is necessary to meet the groundwater regulations.

– Main Injector emittance tails and position stability:• No beam loss if less than 3 mm horizontal orbit shift (vertical

requirements are very loose)• Modeled range of emittance and tails:

– No beam loss if 40 emittance with tails– Expect ~ 20 emittance with tails to 40

– Beam loss monitors look to be very good for tracking groundwater activation.

• Use Beam Loss Budget System to keep track of losses.• Long loss monitors in the carrier tunnel and at every possible

loss point.

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Groundwater Protection: Secondary Beam

• Hadron Absorber values need to be updated for the present cavern and Hadron Absorber design.

Radionuclide Concentrations Relative to the Regulatory Limit

0.000

0.200

0.400

0.600

0.800

1.000

1.200

0 1 2 3 4 5 6

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Airborne Activation

Radioactive Air calculations are being revisited with the present detailed Target Hall design.

– Site-wide permit submitted including NuMI operations in 3/99

– Goal for NuMI is < 45 Ci/year: • ~0.025 mrem/year (1/4 continuous monitoring limit)• Previous NuMI estimates were ~40 Ci/year

– Majority of the air activation occurs inside the Target Pile• Closed system at negative pressure relative to the air

outside the shield.• Preliminary calculations based on re-circulation:

– @ 2250 cfm ventilation, leakage @1500 cfm-> ~20 Ci/year

– Have a variable rate ventilation system from the Target Hall to the decay vent.

– Measurements of air activation will be made early on and the ventilation rate can be adjusted (and the target pile can be better sealed if necessary)

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RAW Water

RAW Water System calculations are in progress.

Preliminary Results:• Target Hall RAW water system:

– Change once per year– Maximum estimates: 4000 Ci/yr, ~20 mCi/ml– Discussions with Don Cossairt that this is OK.

– Alarms to the alarm console in MCR and loss of the beam permit for leak.

• Decay Pipe RAW water system:– Most likely last lifetime of NuMI– Maximum estimates: 11 mCi, ~700 pCi/ml

FRCM Guidelines: not get over 0.67 Ci/ml in RAW systems

Water will be sampled periodically to check levels, alarm systems for water loss, procedures for access to RAW Room.

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Residual Activation

MARS Residuals: 30 days irradiation, 1 day cool down (@2E13protons/sec)

Location Dose Rate

(on contact)

Target Hall: concrete floor of work area ~ mrem/hr

Target Hall: DS horn baffle 25 rem/hr

Target Hall: bottom of T-Block 60 rem/hr

Target Hall: inside cave 50 rem/hr

Target Hall: horn 1 outer conductor 600 rem/hr

Target Hall: Top of T-Block (horn 1) ~40 mrem/hr

Decay Region: outside edge of concrete ~100 mrem/hr

Hadron Absorber: Labyrinth Side ~100 mrem/hr

Hadron Absorber: Core Sides ~ 10’s rem/hr

Hadron Absorber: Core Near Beam ~100’s rem/hr

Hadron Absorber: Steel Blocks ~1’s rem/hr

Hadron Absorber: Back < 30 mrem/hr

Hadron Absorber: Front ~ 1’s rem/hr