Residual Radiation Cooldown: Main Injector

Bruce C. BrownFermilab All Experimenters Meeting

19 March 2012

2Bruce C Brown -- All Experimenters Mtg

Outline

Datao Residual Radiation at Bar Coded Locationso BLM Data each 2.2 sec Main Injector Cycle

Fit Residual Radiation using BLM datao Assume a set of half life valueso Weight BLM data by half life, do linear fit (simple matrix inversion only)

Identify Important Isotopes (activation study)Examine Cooldown Predictionso Collimator Areao ANU Operationo Effects from SeaQuest Operation

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Residual Radiation near MI Collimators

H230

Q230D

V231

Q232D

V301

C301

V303

C303

H304

V305

H306

V307

C307

H308

C308

V309

H230

1

10

100

1000

20110308 20120202

Resi

dual

Rad

iatio

n on

Con

tact

(mr/

hr)

19 March 2012

Formulas for FittingThe BLM system records (for each monitor) a loss integral (LI) for each MI Cycle. We

sum these over ten minute intervals (Ts = 600 sec) – to quantas, LIj.

For each isotope we sum these quantas weighted by the half-life

The fitting hypothesis assumes that the measured residual radiation at measurement time, TM is a linear sum of the weighted quata sums over the set of isotopes

The physics of the loss pattern and isotope production, loss monitor geometry, bar code monitor location geometry and Geiger tube energy response multiply to create one linear constant EI.

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Losses LI232 Since Oct 2006

10/10/2006 2/22/2008 7/6/2009 11/18/2010 4/1/20120

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

a(week avg) b(312.30D) c( 27.70D) d( 5.59D)

Aver

age

or W

eigh

ted

LI232

Loss

(mr/

sec)

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Activation for MI Steel Samples(Normalized to BLM rate)

Compare Normalized Activation of MI Steel Sample

Sample Half Life Average Ratio days Shielded Unshield

/AverageShielded

Br-76 0.675 19639.73Co-60 1925.8 138487.1Cr-51 27.7 284194.5 100.5783Fe-52 0.344792 1266.819 201.9571Fe-59 44.5 327404.6Mn-52 5.591 79053.71 102.5272Mn-54 312.2 639444.8 99.31633Mn-56 0.1074 6771619 4.545409Na-24 0.62329 4104.662 59.35237Sb-122 2.7 552517.2 1.914643Sb-124 60.2 202194.8Sc-44m 2.44 5385.168 260.7752Sc-46 83.83 16852.09 215.3617Sc-47 3.341 10350.71 131.7161Sc-48 1.82 2048.755 108.3398V-48 15.98 47371 149.0295Sc-44 0.165417 10380 278.141

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Residual Radiation w/ Fit at Q232D

19 March 2012

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Cooldown Prediction – D230D

0 50 100 150 200 250 300 350 4001

2

3

Residual Radiation Decay for Q230D Using Fit from February 2012

2 Weeks Full Rate 2 Weeks 1/2 Rate 2 Weeks 1/4 Rate 2 Weeks 0 Rate 1 Week 1/2 Rate 1 Week 1/4 Rate 1 Week 0 Rate

Days after Shutdown Begins

Resi

dual

Rad

iatio

n N

orm

aliz

ed to

Ra

te a

fter

Yea

r

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Cooldown Prediction – Q230D

0 5 10 15 20 25 30 35 40 45 501.8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

Residual Radiation Decay for Q230D Using Fit from February 2012 Use Mn-54, Cr-51, Mn-52, Mn-56

2 Weeks Full Rate 2 Weeks 1/2 Rate 2 Weeks 1/4 Rate 2 Weeks 0 Rate 1 Week 1/2 Rate 1 Week 1/4 Rate 1 Week 0 Rate

Days after Shutdown Begins

Resi

dual

Rad

iatio

n N

orm

aliz

e to

Ra

te a

fter

Yea

r

19 March 2012

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Compare Cooldown Fits

Q230DV231Q232DV303 H304 V305 H306 V307 V309

-0.5

0

0.5

1

1.5

2

2.5

3

3.5

4

Isotope Ratios at Correctors

Mn56/Mn54 Mn52/Mn54 Cr51/Mn54

Equi

libriu

m A

ctiva

tion

Ratio

C301 C303 C303 C3070

10

20

30

40

50

60

70

Isotope Ratios at Collimators (Shielded)

Mn56/Mn54 Mn52/Mn54 Cr51/Mn54

Equi

libriu

m A

ctiva

tion

Ratio

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Predictions for Nova EraOperation of the Main Injector Complex for the NovA era will achieve 700 kW operation by

accelerating the similar intensities with higher repetition rates. The losses will be similar and much of the loss will be at the same locations.

The weighted loss rate LW for any isotope will reach an equilibrium for the new rate at 2.2/1.3 of the current (nearly) equilibrium rate.

Long Half Life isotopes will continue to build toward equilibrium.Measured Residual Radiation results from the sum of the specific activities, SA of produced

isotopes weighted by geometry effects and the energy response of the measurement instrument (Geiger Counter).

Since iron is typical of the materials we activate, we look at the chart of identified isotopes and see that the only long lived isotope not included in previous studies is Co-60 with a half life of 1925.8 Days (5.27 years).

Comparing the ratio of SA for Co-60 with that for Mn-54 we predict that when starting a shutdown after achieving equilibrium, we expect 13.8/63.9 = 21.6% enhancement of the long lived components (ignoring differences in geometry or energy response) .

Planning for a long shutdown in the Nova era will be impacted primarily by the 70% higher loss rate (assuming same loss fraction) with little impact from build-up of long half life isotopes.

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Activation Study for SeaQuest

Observe Losses for Current Operation at 3E11 pTypical activation data and loss rates will predict

residual radiation due to SeaQuest slow spill operation at 1E12 or at 1E13 ppp and expected repetition rate. Could try to use 8 GeV activation data but 120 Gev will be somewhat different physics and geometry

Will wait for measurements, then scale with rate

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Losses for Operation 8 – 11 March

19 March 2012

Beam21

LI520D

LI522A

LI521A

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Typical Rates for 1E12 protons/cycle

Assume we run 1 SeaQuest cycle per minute and take losses measured March 8-11, compare to 10 week average of some collimator region BLM’s

19 March 2012

Location mR/sec/1E12LI520A 0.409090909LI520B 54.81481481LI520C 157.7104377LI520D 18.21548822LI520E 10.94276094LI521B 18.49158249LI522A 0.777777778

Location mR/sec LI230 2.5874 LI303 55.2515 LI307 9.8107 LI309 48.5938

Resonant Extract Area Collimator Area

Residual Radiation Measurements following a week or two of operation are needed

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Acknowledgments

This work had been built on the efforts of many individuals and groups at the lab. Some of them include:

Guan Wu (MI Dept) for Application Program Support Operations and MI Department for vigilant tuning APC Energy Deposition Gp (Nikolai Mokhov and colleagues) Vernon Cupps (retired) for Activation Measurements Everyone who contributed to the MI BLM System

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ReferencesSome Console Applications for Displaying Main Injector BLM Measurementshttp://beamdocs.fnal.gov/AD/DocDB/0032/003299/002/Beams-doc-3299.html

Residual Radiation Monitoring in the Main Injector with the ROTEM RAM DA3-2000 Radiation Survey Meter

http://beamdocs.fnal.gov/AD/DocDB/0035/003523/001/Beams-doc-3523.html

Measuring correlations between beam loss and residual radiation in the Fermilab Main Injector. http://lss.fnal.gov/archive/2010/conf/fermilab-conf-10-368-ad.pdf

Activation of Steel and Copper Samples in the Main Injector Collimator Regionhttp://beamdocs.fnal.gov/AD-public/DocDB/ShowDocument?docid=4046

19 March 2012