NUMINBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 1

NuMI Beamline
Radiation Safety Issues
Nancy Grossman
FNAL
NBI03 November 2003

NUMI

NuMI Beamline Radiation Issues
•
•

•
•

Overview
Some Details– Air Activation– Groundwater Protection– RAW Water Calculations, Containment– Air and Water Monitoring– Residual Dose Rates/Hot Component Handling
Decontamination & Decommissioning
Conclusions

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 2

NUMI

Radiological Safety
Overview

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 3

Regions
Radiological Areasz
MI/ExtractionzPrompt radiationz
Carrier Tunnel Lined Regionz
Residual activation of enclosures andz
Carrier Tunnel Drill &Blast
components
Regionz Hot component handlingz
Pre-target RegionzRadioActive Water (RAW) systemsz
Target Hallz
Decay Tunnelz Cooling systemsz
Hadron Absorberz
Airborne activationz
Muon Alcovesz
Groundwater
Mitigation
activation/contaminationz
Passive shielding
Designs are reviewed in accordance withz
Interlocked Radiation Detectors
Chapter 8 of the Fermilab Radiologicalz
Beam Permit System (BPS)
Control Manual (FRCM).
– Only extract if beamline ready& “good” beam

NUMI

NuMI
Radiation Safety Overview
Conceptual Plan
View:(not to scale)(5/01)
Labyrinth
Carrier
Pipe

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 4

Interlocked door or gateContinuous air monitor“Door”
Labyrinth
Stripline Penetration

Muon
Alcoves

MINOS
Enclosure
Door/Gate to Prevent
US Wandering
Conceptual Elevation
View:(not to scale)

MI/NuMI
Stub

Muon
Alcoves

PreTarget
HadronAbsorber

MINOS
EnclosureNUMI

Radiological Safety:
Assessment Process & Issues

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 5

1. Presentations to NuMI Radiation Safety Advisory Committee (NRSAC)• Initial validation of calculation methods
2. “Preliminary Radiation Shielding Assessment” to start civil construction in 1/00
3. Final “Radiation Shielding Assessment” approval needed to operate with beam
– This occurs near the end of the project– Need “buy-in” on methodologies and rough results early on in design phasein order to have workable designs & no surprises
Issues• We almost always underestimated the amount of work needed to determine
radiation safety input to designs• Radiation calculations almost always lagged design effort– Not enough manpower, experts– Often brought in non- radiation protection physicists to do the work
– Used overall experience and general expertise of radiological personnel at
FNAL until time could be spent to better calculate the effect.
– At times this required modifications later, none significant fortunately

NUMI

NuMI Radiation Protection
Overview

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 6

Prompt Radiation (source term: MARS hadronic flux density):• FNAL “standard” method/model– Based on personnel-sized labyrinths with bends– Rough (conservative) correction factor for long and/or small penetrations• NuMI method/model (brought old model up to date)– More accurate for long straight and/or small penetrations– Automatically looks at “short circuits” and does curved penetrations• Once start running, hope to benchmark this methodology
Groundwater (source term: MARS star density in rock):• FNAL “standard” method/model– Beams in glacial till (~clay), thus water assumed static (no flow)– Model migrates water to aquifer, few cm’s/yr movement, decay in transit• NuMI method/model (NuMI in aquifer, water flows into tunnel at 350 gpm)
– Water only activated as long as resident in rock, then pumped to surface• Activation of water less an issue where water flows than at interface region

NUMI

NuMI Radiation Protection
Overview

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 7

Air Activation (source term: MARS hadronic flux density):• FNAL “standard” method/model– Single volume of activated air, leaves activation region, decays in transit– CAP 88 program required for use for determining rates at site boundary• NuMI method/model– 2 activated volumes, one highly activated & confined, leaks to outer volume• Air in Target Pile and Hadron Absorber must be confined as much as possible
Cooling Systems Activation (source term: MARS hadronic flux density):• No FNAL “standard” method/model, estimates made, measure as run• NuMI method/model– Develop method/spreadsheet for calculation similar to air activation
spreadsheet– Use flux densities from MARS and cross sections• Levels get very high for horns, target – determine frequency of changes

NUMI

NuMI Radiation Protection
Overview

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 8Component Activation (source term: MARS residual dose rate):• FNAL “standard” method/model– Previously used CASIM star density with correction factors– MARS is now the “shielding code” that must be use & gives residual doserates
• NuMI method/model– Benchmarked MARS residual dose rate values at FNAL AP0– Use MARS residual dose rates with uncertainty factors based on thebenchmark data
• Cracks between shield blocks are important, but not as big a contributor toresiduals as was generally thought• Material composition can be very important, especially sodium content of
concretesome details to follow…..

NUMI

Groundwater Protection

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 9•Hired several groundwater consultants to determine water levels and flow rates
around the unlined regions of the NuMI tunnel.
– All water within 10’ (3 m) of tunnel flows into the tunnel(within the aquifer region)– Most water flows in rapidly through the fractures– Determine an average inflow velocity based on groundwater consultant’s
inflow estimates•

Use the Fermilab Concentration Model, modified to allow for water flow
– Fermilab Reports TM1851, TM2092, TM2009 (NuMI).
– Updated to include our latest understanding of groundwater contamination by
22Na and 3H, the only radionuclides of concern (NuMI-B-495)– Flow dependent residency time of water in the region of the beamline (inflow
or outflow) where applicable.
– Irradiation time = residency time of the water in the activation region– Groundwater Methodology document completed and approved.

NUMI

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 10Groundwater Protection
Standard Groundwater Model
Static water
Leaching based on glacial till, 90%leaching volume of water
Radionuclide production based on
Borak et. al

NuMI
Water flows
Dolomite with fractures rockwith porosity -> water
volumeDirect production of tritiumin water

Resulting Model
Inflow ( 22Na retarded)"Leaching" volume of water isthe porosity "volume"
22

Na: FNAL measurement
3
H: based on Borak et.al.

Calculations must be below the regulatory limit including uncertainties (FNAL memo, DOE
Environmental Assessment response letter)– Use uncertainties in all parameters to determine overall uncertainty• Determine effect on results and add in quadrature
Calculations are conservative (for inflow regions):– Comparing concentrations in inflow water, which will be pumped to the surface, togroundwater limits– Model includes worst case conditions (dry), which we did not encounter– Does not include decay during migration to a well
• Water along the unlined beamline tunnel can not get to any well other than the NuMI beamline“well”– Does not include dilution & dispersion in transit to a well
Bottom Line: Ensure compliance with monitoring well(s)NUMI

Groundwater Protection:
Primary Beam- Clean•••

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 11

Open apertures and “Autotune” will help keep beam nominal and “clean”– Have determined power supply regulation needed for clean beam
– Beam optics dynamic aperture matches that of the Main Injector
Beam to NuMI only when conditions are nominal (Beam Permit System, BPS)
– Magnet currents within nominal limits this pulse– Limit on beam loss last pulse and integrated beam loss (beam loss monitors,
Beam Loss Budget Monitor, BLBM)– Interlocked radiation detectors (detect large loss in carrier tunnel region)• Part of Radiation Safety System to prevent multiple accident pulses– “Clean” Main Injector beam
Detailed simulations (MARS14) of the primary beamline and possible accident andDC (continuous) loss conditions have been studied.
– Strong indication that beam loss monitors (BLM) signals closely track
groundwater activation levels.
– Testing BPS in MiniBooNE

NUMI

Groundwater Protection:
Primary Beam

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 12

MARS14 Primary beamline: 7 different regions based on geometry & geology(water flow rates different in each region)• water velocity varies from a few cm’s/year in the upstream glacial till region to• 50-200 meters/year in the lower rock regions

NUMI

Groundwater Protection:
Primary & Secondary Beam

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 13

Hadron Absorber

Secondary Beam (Inflow Region) results: 0.200(no accident condition)

Decay Region(Upper Ordovician)Target Hall

Decay Region(Lower Silurian)

Decay Region(Middle Silurian)

Relative Concentration

Primary Beam:
Lined Carrier Tunnel, Interface Region - driving region:
Groundwater limit: 3H: 20 pCi/ml, 22Na: 0.4 pCi/ml– 125 lost pulses in 1.5 years
Surface water: 3H: 2000 pCi/ml, 22Na: 10 pCi/ml
Dimensions:Radionuclide Concentrations Relative to the• 6’ (1.8 m) diameter tunnel,
Regulatory Limit• 1’ (0.3 m) diameter beam pipe 1.200• ~100’ (30 m) long section
1.000
Accident Loss:
0.800• Unlikely to happen often.
• Loss detected and next pulse not
0.600
extracted.
Normal Loss: ~10-4/4e13ppp
0.400

0.000
0

1

2

3

4

5

6

NUMI

Airborne Activation

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 14

Radioactive Air calculations:– Goal for NuMI is < 45 Ci/year:• ~0.025 mrem/year (1/4 continuous monitoring limit)– Majority of the air activation occurs inside the Target Pile
• Closed system at negative pressure relative to the air outside the shield(recirculated at ~25,000 cfm, 30 km/hr)• Preliminary calculations based on re-circulation:– @ 700 cfm (20 m3/minute) vent rate to stack, leakage @700 cfm-> ~20
Ci/year (4E13 p/pulse)– Hadron Absorber contributes a significant amount also
• Need to seal the Hadron Absorber.
• Preliminary calculations based on sealing:– @ 2250 cfm (64 m3/minute) vent rate to stack, leakage @200 cfm-> ~10
Ci/year (4E13 p/pulse)– Have a variable rate ventilation system for both stacks.
– Measurements of air activation will be made early on and the ventilation rates
can be adjusted (and both piles can be better sealed if necessary)

NUMI

Airborne Activation

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 15

Air Path

Elevation
Top air seal
Cross Section
Air from chiller
runs down outsideof pileStripline
Concrete Cover (oops –really only one layer)“Carriage” - Module
Support Beams
Horn Shielding Module
Horn
Steel Shielding
Air returns down centerof beam-line
Concrete Shielding

NUMI

Radioactive Water (RAW )(3H, 7Be main concerns)

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 16

Activity in cooling water, maximum estimates, 1 year of operation, 1 hour cooldown– Horn 1 RAW water system (horn 2 RAW about a factor of 3 less):• Change ~ yearly• 7 Ci/yr, ~140 µCi/ml– Target RAW water system:• 1 Ci/yr, very small volume– Decay Pipe RAW water system:• Most likely last lifetime of NuMI
• 11 mCi/yr, ~700 pCi/ml– Hadron Absorber RAW water system:• Most likely last lifetime of NuMI
• 40 mCi, ~0.1 µCi/ml
Water will be sampled periodically to check levels, alarm systems for water loss,
procedures for access to RAW Room.
(FRCM guidelines recommend not exceeding 0.67 µCi/ml)

NUMI

Radioactive Water (RAW )NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 17

Target Hall RAW Water – Secondary Containment• Slow Leak Scenario: Surface discharge much less than the limit, so that longterm leaks are not a problem.
• Sudden failure (20 Ci in system, 20 out of 100 gallons leaks before shutdown• Water can not go directly in to the under drain, seepage through the concrete
floor is sufficient
H3

Be7

8 piC/ml

47 piC/ml

0.4 Ci

2.1 Ci

Water flow rate

150 gal/min

150 gal/min

Surface Water Limit

2000 piC/ml

1000 piC/ml

6 hr

61 hr

resulting water radio
activation, slow leakresulting water radio
activity, sudden failure

sudden failure duration(to not exceed limit)

NUMI

Air and Water Monitoring

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 18

Operation of the NuMI Facility will be included in the comprehensive
laboratory water and air monitoring program
Air:• Permanent air monitors will be located at both ventilation shafts in the decay
region (Hadron Absorber air and Target Hall air release points)• Probably 3rd monitor at the release point in the upstream end, good
indication of beam loss
• Measurements will be watched closely when NuMI starts up at low intensity(flow rates can be decreased, shielding piles can be better sealed)
Water:• One monitoring well is located just down gradient of the carrier tunnel
interface region.
• Regular sampling of the monitoring wells (monthly initially)• Regular sampling of the water pumped from NuMI and released to the surface
waters.
• Regular sampling of the cooling water systems (RAW and LCW)NUMI

Residual Dose Rate
Estimation with MARSNBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 19

Much Progress has been made in this area:– “Benchmarking Residual Dose Rates in a NuMI-Like Environment”, I. Rakhno
et. al.
• Agreement is within a factor of 3
• Must carefully put in geometry, materials and get sufficient statistics(neutrons dominate as source)– Detailed Target Hall geometry around horn 1 is complete.
• Cracks around module and between T-blocks• Stripline penetration– Robust draft Hot Horn Handling procedure, drawings and dose estimates arecomplete.
details to follow….

NUMI

Residual Dose Rates with MARS:
Horn 1, Module, T-Blocks, Cracks

Concrete Cap
Air
T-Blocks
Horn

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 20

NUMI

MARS: Horn 1 Stripline Cross
Section Flux

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 21NUMI

MARS14: Target Chase &Residual Dose Rates

mrem/hr on contact,
30 day irradiation, a
day cooldown

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 22

<1
0.3

~2

100 mrem = 1 mSv

Inner side of top blocks
Bottom of T-blocks
98,000Inner side of bottom blocks
100 mrem= 1 Sv

0.2
2.5
31

NUMI

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 23

Residual Rate Distributions

Top Curve: inner side of bottom set of steel blocks in chase
Shaded Curve: bottom of T- Blocks
Bottom Curve: inner side of top steel blocks in chase

100 rem = 1 Sv

NUMIResidual Activation
Location

Dose Rate(on contact)< 1 mrem/hr~ 5 mrem/hr~ 2 mrem/hr

Target Hall: concrete floor of work area
Target Hall: Top of T-Block (horn 1)
Target Hall: Bottom of concrete “cap”
Target Hall: near hot cell
Target Hall: near air handling equipment
Target Hall: DS horn baffle (old result)
25 rem/hr
Target Hall: bottom of T-Blocks above horn 1
100 rem/hr(average)
Target Hall: inside cave walls around horn 1
80 rem/hr
Target Hall: horn 1 outer conductor
600 rem/hr
Target Hall: target
6000 rem/hr
Target Hall: upstream wall
Decay Region: outside edge of concrete~100 mrem/hr
Decay Region: emergency egress (rock & conc)~100 mrem/hr
Decay Region: upstream window
5 rem/hr
Decay Region: downstream window
700 mrem/hr
Decay Region: decay pipe
30-200 rem/hr
Hadron Absorber: Core Near Beam
~100’s rem/hr
Hadron Absorber: Core Sides~ 10’s rem/hr
Hadron Absorber: Steel Blocks~1’s rem/hr
Hadron Absorber: Front~ 1’s rem/hr
Hadron Absorber: Labyrinth Side
~100 mrem/hr
Hadron Absorber: Non-Labyrinth Side
Hadron Absorber: Top
Hadron Absorber: Back< 30 mrem/hr

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 24

MARS13 Residuals:
30 days irradiation,
1 day cool down(@2E13protons/sec)
100 mrem = 1 mSv

NUMI

NuMI Hot Component Handling

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 25

NuMI Target Hall Utilizes Three Basic Beamline Elements- Horn Protection Baffle & Target Assembly- Magnetic Focusing Horn 1- Magnetic Focusing Horn 2
Basic Operational Criteria- Protection baffle/target assembly and horn 1 require motion
capability in beamline chase- Shielding design should allow the position of horn 2 to bechanged along the beamline to accommodate a LE, ME, andHE beamline configuration- Low energy target is designed for 107 pulse, 1 year lifetime- Focusing horn 1 is designed for 107 pulse, 1 year lifetime
We anticipate changing failed horns and targets during the experiment(and allow flexibility for configuration changes)

NUMI

NuMI Target Hall

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 26

NUMI

NuMI Target Hall
Beam line is below floor level
Remote rotating
crane hook

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 27

Temporary Stackup
of removed shielding
Steel from module middle
Concrete from over horn
Horn+Module in transit
Stripline
Concrete CoverModule Support Beams
Horn Shielding Module
Horn

Beam passageway (chase)is 1.2 m wide x 1.3 highSteel Shielding
Air Cooling Passage
Concrete Shielding

NUMI

Target and Horn Modules
Motor drives for transverse
and vertical motion of carrier
relative to module

Target/Baffle
Module

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 28

25 cm wide, 2 m deep Steel endwallswith positioning, water, electric feedthroughs

Horn 1 Module
RemoteStripline
Clamp
Stripline

BaffleCarrier

Water tankTargetHorn 1
Target moves relative tocarrier for insertion into horn for L.E. beam

NUMI

Hot Handling Work Cell
Mount/dismount components on modules

Horn connections are all done throughthe module by person on top of hot cell

Railing
ModuleLead-glass window
Horn
Remote lifting table
Concrete walls
3m

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 29

NUMI

Lifting Table in Hot Cell

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 30

Push horn or target up intomodule remotely – 5 degrees
of motion

Both tables
move together
along beam direction

Each table has independent verticaland transverse motion

NUMI

Lifting Fixture for Module

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 31

Remotely change pick point to match center of gravity

Teeth disengaged toenable movement ofhook relative tolifting fixture frame

Teeth engaged at
center of gravity
for horn 1 pick

Lifting
fixture box
frame
Module hook
Pins to engage module hooks

NUMI

Hot Horn Replacement Procedureitalics denotes remote operation (camera)
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 32

Remove concrete cover, use to build temporary shield
Disconnect utilities from top of module
Crane the shield T-blocks from module to temporary shield pile
Crane module+horn to hot cell (close cell door, place covers on top)
Disconnect utilities through module, loosen horn attachment
Lower horn with lifting table
Crane hot module out of way (back in chase)
Crane hot horn to Morgue (hot horn storage area), cover
Crane new horn in Hot Cell
Crane hot module to hot cell
Insert horn onto module with remote lifting table
Connect horn utilities through module
Crane module+horn back into beamline
Insert shield T-blocks into module
Connect utilities to top of module
Replace concrete cover

NUMI

Hot Handling DoseNBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 33

for hot horn replacement

Source Description
Walls, Floor, & Ceiling
Bottom of Horn Module
Top of Horn Module
Horn Module Connection Region
Inside Horn Chase (Steal)
Face of Unremoved H-Blocks
Horn (Side View)
Horn (Upstream View)
Horn (Downstream View)
Bottom of T-Blocks From Horn Module
Top of T-Blocks From Horn Module
Concrete H-Block Shield Wall #1
Concrete H-Block Shield Wall #2
Single Wall Reflection From Chase
Material In Morgue
Top of T-Blocks in Target Module
Top of Target Module

Hide Repair Doses

Dose Rateon Contact(mrem/hr)
0
213,083

RSO Measured (30 Day, 1 Day) (30 Day, 7 Day) (252 Day, 1 Day) (252 Day, 7 Day)
0
0.05
5.50E-03
6.13E-02
1.58E-02
0
1000006.14E+04
2.55E+05
2.13E+05
01
6.14E-01
2.55E+00
2.13E+00
01
6.14E-01
2.55E+00
2.13E+00

2
2

0
0
0
0
0
0
0
0
0
0
NA
0
0

66
6
19,39925,86538,797
213,083
2
3
3
0
0
2
2

1.90E+01
2.20E+00
7.04E+03
9.38E+03
1.41E+04
6.14E+04
6.14E-01
1.10E+00
1.10E+00
6.14E-03
NA
6.14E-01
6.14E-01

7.89E+01
2.45E+01
6.13E+05
8.18E+05
1.23E+06
2.55E+05
2.55E+00
1.23E+01
1.23E+01
2.55E-02
NA
2.55E+00
2.55E+00

6.61E+01
6.34E+00
1.94E+04
2.59E+04
3.88E+04
2.13E+05
2.13E+00
3.17E+00
3.17E+00
2.13E-02
NA
2.13E+00
2.13E+00

Technician #2

Radiation Safety Official

Engineer

1.22E+00

6.82E-02

2.47E-02

Dose Per Person (mrem)
Crane Operator Technician #1

HORN WILL BE REPAIRED
HORN WILL BE DISCARDED

31
20
6000008000001200000
100000
1
10
10
0.01
NA
1
1

4.13E+00

1.41E+00

Total Dose For All Personnel (mrem)
HORN WILL BE REPAIRED
HORN WILL BE DISCARDED

6.84E+00

Note 1 sievert = 100 rem

NUMI

Decontamination &Decommissioning

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 34• Guidelines of FESHM 8070 will be used for D&D of the NuMI Beamline.
• No hazardous materials have been used in construction of the beamline(except lead bricks for hot cell shielding, ones already activated).
• Major isotopes produced will have 2.6 and 5.3 year half-lives (exception oftritium).
• Sump pumps removing water from the NuMI tunnel will continue operation.
• Items put in the NuMI tunnel during construction are being chemicallyanalyzed.
– Mostly those items not accessible after tunnel construction– Grout, rock bolts, shotcrete, wire mesh

NUMI

Summary/Conclusions•

NBI2003
NuMI Radiation Safety
Nancy Grossman (FNAL)
November 2003
Page 35

We have come a long way:
– Much progress in developing new methodologies for air,groundwater, residual radioacitvation– Building/installing beamline– Culture, acceptance of “new” methodologies is occurring• Mainly groundwater and beam permit system understanding• Need to better communicate outside the project•

Higher Intensity beams, deep underground beams have new issues– Groundwater activation was never much of an issue at FNAL
• NuMI is in a drinking water aquifer– Need to minimize beam loss for groundwater & residual rates• Need very good beam control– Air needs to be contained, recirculated in target pile and beamstop, air levels too high otherwise