Groundwater Activation Calculations for E872

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1 0 Fermi National Aelerator Laboratory FERMILAB-TM-1944 Groundwater Ativation Calulations for E872 E872 W.S. Freeman The E872 Collaboration Fermi National Aelerator Laboratory P.O. Box 500, Batavia, Illinois August Operated by Universities Researh Assoiation In. under Contrat No. DE-AC02-76CH03000 with the United States Department of Energy

2 Dislaimer This report was prepared as an aount of work sponsored by an ageny of the United States Government. Neither the United States Government nor any ageny thereof, nor any of their employees, makes any warranty, express or implied, or abbumes any legal liability or responsibility for the auray, ompleteness, or usefulness of any information, apparatus, produt, or proess dislosed, or represents that its use would not infringe privately owned rights. Referene herein to any speifi ommerial produt, proess, or servie by trade name, trademark, manufaturer, or otherwise, does not neessarily onstitute or imply its endorsement, reommendation, or favoring by the United States Government or any ageny thereof. The views and opinions of authors expressed herein do not neessarily state or reflet those of the United States Government or any ageny thereof.

3 Fermilab Groundwater Ativation Calulations for E-872 William S. Freeman July 28, 1995 The E872 beam dump geometry has been modeled in CASIM and alulations have been done to determine the annual limits for protons on target. Results are presented using both the single resident well model (SRWM) and the newlyapproved onentration model (CM). The onlusion is that the target/ dump design is adequate for the maximum number of protons on target requested by the experiment, whih is >lxlolb protons per year at 800 GeV. Desription of Modeled Geometry The E872 target/beam dump will be loated near the upstream end of the PW8 experimental hall. The target/ dump was modeled as a 1 meter long retangular tungsten blok with transverse dimensions 10 m (h) x 5 m (w). It was reessed in surrounding steel shielding with its upstream end loated 1 meter inside the shield. Beause the beam elevation at the target loation is only 91 m above the floor it was deided to support the target from above to allow the maximum possible shielding beneath the target. Thus the target was assumed to reside in a avity with internal dimensions of 26 m (h) x 20 m (w) with only a 1 m learane between the bottom of the target and the steel shielding (see figure 1). The width of the avity was determined by the need to use a "half-density" tungsten target for part of the running period with provision to move it into the beam remotely. This halfdensity target was modeled as five tungsten bloks, eah of dimension 10 m (h) x 5 m (w) x 10 m (1), equally spaed beside the full density target (see figure 2). The beam was assumed to be targeted on the enter of the upstream fae of the fulldensity target for the results reported here. A large steel sweeping magnet (SELMA) will be loated immediately downstream of the target/ dump. The magnet aperture will be ompletely filled. For simpliity this magnet was modeled as a solid, unmagnetized iron blok with dimensions 190 m (h) x 290 m (w) x 700 m (1), entered on the beam line. (see figure 3). The beam elevation above the floor inreases from 91 to 182 m beginning at the upstream end of the SELMA magnet. The magnet rested on a 45 m thik onrete blok plaed on the floor of the hall. An extra 30 m of steel was added to the upper surfae of the magnet to redue residual ativation rates to aeptable levels. A seond sweeping magnet (MuSweep 2) will follow downstream of SELMA. It has a "piture-frame" ross setion with one vertial side entered on the beam axis and is 500 m long. It also was modeled as solid, unmagnetized iron with ross-setion dimensions shown in figure

4 For ompleteness, the downstream passive steel muon absorbers were also inluded in the modeled geometry with dimensions as shown in figure 5, although the bulk of the stars and the highest star density in the soil surrounding the enlosure are expeted to be onentrated in the viinity of the target and the SELMA magnet and not around the muon absorbers. The PW8 enlosure was modeled with 45 m thik onrete walls, floor, and eiling. The upstream region of the hall had a retangular ross setion with inner dimensions shown in figure 6a and 6b. Note that the beam elevation is 91 m above the floor in the upstream region. The downstream region has a larger ross setion due to a lower floor elevation. The enlosure was assumed to be surrounded by soil out to a radius of 750 m whih ensured a minimum of one meter of earth in all radial diretions. Plan and elevation views of the full modeled geometry are shown in figures 7a and 7b. The CASIM FORTRAN geometry file is reprodued in Appendix 1. The CASIM input data file is shown in Appendix 2. Results Single Resident Well Model (SRWM) The total number of stars produed in the soil surrounding the PW8 enlosure was alulated to be 0.10 ± This was obtained from a CASIM run using 100,000 inident partiles at 800 GeV. The final onentration of the ith radionulide tna 1 (in pci /ml-yr) is given by.. N S K L e(-y/v;r;) final = p T t t ' T 6.47Xl0 13 l (eq. 1) where is the average number of inident protons per year is the total number of stars per proton produed in the unproteted soil region is the number of leahable atoms of the ith nulide produed per star ( atoms/star for H3, atoms /star for Na22) the mean deay life for the ith nulide (17.7 years for H3, 3.74 years for Na22) the vertial veloity of the ith nulide (2.19 m/yr for H3, 0.98 m/yr for Na22) y the vertial distane from the soure to the aquifer (11.3 meters) -2-

5 6.47x1Ql3 onversion fator to get proper units and based on the standard 40 gallons per day pumped from a single well for an entire year The sum of the ratios of onentrations to their allowed regulatory limits must be less than 1 to insure that the annual 4 mrem per year limit for ommunity drinking water supplies is not exeeded (ref: 40 CFR 141). That is, C(H3) + C(Na22) s (eq. 2) Using equations 1 and 2, the maximum permitted number of protons on target per year was determined to be 2.0 x 1Ql8. The results are summarized in Table 1. Conentration Model (CM) The reently approved onentration model (ref: TM1851, Malensek, et al and Environmental Protetion Note 8, Cossairt) also was used to determine the allowed number of protons on target per year. In the onentration model the initial onentration C;, for radionulide, i, is given by where NP =Np Smax O.OI9 K; L; I 1.17 x p. W; is the number of inident protons per year (eq. 3) smax is the maximum star density per inident proton in the unproteted soil K; is the radionulide prodution probability per star ( atoms/star for H3, 0.02 atoms I star for Na22) L; is the leahability fator for the radionulide ( 0.9 for H3 and for Na22) p is the soil density (2.25 gm/ m3 for moist soil) w; is the weight of water divided by the weight of soil that orresponds to 90% leahing (0.27 for H3 and 0.52 for Na22) The final onentration in groundwater, ;"nat, is related to the initial onentration by t<nat = C. R. R. R i i till mix dolomite (eq. 4) where Rt;u is a redution fator in the model that takes aount of the migration of radionulides downward through the soil (glaial till) to the aquifer and allows for -3-

6 radioative deay en route. The additional redution fators, Rmix and Rdolomire are assumed equal to one. The redution fators are given by R (H3) = 1 0. [-0.3 d(meters)] r;u e (eq. 5) R ('AT 22 )- 1 Q. [-0.92 d(meters)j i't;u 1va -. e (eq. 6) where dis the distane from 1.84 meters below the point of maximum star density to the aquifer (11.3 meters). Due to the lak of ylindrial symmetry of the modeled CASIM geometry, it was neessary to define separate regions of soil beneath the target/ dump and to determine the star density in those regions by dividing the total stars produed in the regions by the volume of the regions. Two retangular regions were defined below the beam line. Eah of them was 100 m (1) x 30 m (w) x 15 m (h). The first was entered diretly below the 100 m long tungsten blok immediately beneath the onrete floor slab. This was beneath the thinnest part of the steel shielding surrounding the target and is in the region where the maximum star density in the unproteted soil would be expeted. The seond region was beneath the upstream end of SELMA, immediately downstream of the first region, and also entered below the beamline immediately beneath the floor slab. However, the floor slab is about three feet lower in elevation at this loation and there is also an additional 45 m of onrete on whih the SELMA magnet rests, so this region would be expeted to have a redued star density. These regions are indiated in figure 7b. The total number of stars per inident proton produed in the region beneath the dump was 1.9 xlq-3 (±0.6x10-3) stars, based on a CASIM run with 100,000 inident partiles at 800 GeV. Dividing by the region's volume of 4.5x104 m3 gives a maximum star density of 4.2x1Q-8 stars per m3 per proton. Solving for the initial and final onentrations for H3 and Na22 in terms of N" using equations 3 through 6, substituting the results into eq. 2 and solving for N" gives a maximum of 4.4x1Q18 ( ±1.3x1018) protons per year, averaged over three years. Conlusion The beam dump shielding design as modeled for the E872 experiment in PW8 is adequate for the number of protons on target required by the experiment using either the Single Resident Well Model or the Conentration Model. -4-

7 APPENDIXl CASIM FORTRAN Geometry File SUBROUTINE CASIMGEOM C USER SUBROUTINE DESCRIBING PROBLEM GEOMETRY C GIVEN ( X,Y,Z ) IN CM, ENTRY USRGEOM RETURNS C MATERIAL INDEX N (GE.-1 AND LE.9) C MAGNETIC REGION INDEX M (GE.0) C CONVENTIONS NM=-1 VACUUM WITH MAGNETIC FIELD PRESENT C 0 VACUUM NO MAGNETIC FIELD PRESENT C 1-9 MATERIALS C 99 Outside of defined geometry C MAGNETIC FIELD INDEX M MUST CORRESPOND TO INDEX IN C SUBROUTINE USRFIELD WHERE B VECTOR IS DEFINED AS A FUNCTION OF C LOCATION IMPLICIT NONE SAVE C========================== Inlude HIBI.CIN =========================== C HIBI REAL ZLIM, RLIM COMMON/HIBI/ ZLIM, RLIM C============================ End Inlude ============================== INTEGER N, M, KT REAL X, Y, Z, XM, YM, ZM, R REAL AX, AY Hard-wire the limits to your geometry here. This setion gets C alled one per Job. The 'SAVE' above insures that values set are retained after the subroutine is exited. ZLIM=3400. RLIM=750. RETURN C This setion gets alled whenever CASIM wants to hek what material C a partile is in, given X, Y, z ENTRY USRGEOM(X,Y,Z,N,M,KT,XM,YM,ZM) C The E-872 beam dump model geometry for a Casim alulation of ground water C ativation. C Inluded are a full and half density tungsten target surrounded by steel C shielding followed by the SELMA magnet followed by MuSweep 2 C followed by three long piees of steel shielding/absorber for the C detetor. The beam is targeted on the full density side of the target. C Steel shielding out to a distane from the beam line of 120 m has been C added around the target/dump on the top and sides. Steel out to C a distane of m from the beam elevation has been added below the C target/dump. This is the maximum allowed due to the floor elevation. C The target is reessed by 100 m along the beam diretion -5-

8 C C into the steel that surrounds it. 10 m thik layer of tungsten (20 m wide) is installed below the dump to ompensate for the redued steel thikness. (COMMENTED OUT FOR THIS RUN) C The Selma magnet is modeled as a steel blok 220 m x 290 m x 700 m C with a filled gap. The vertial width has been inreased from 190 to 220 C to see effet on ground water by adding a foot of steel on top. 45 m of onrete has been added on the floor below SELMA. This is a base C blok on whih SELMA rests. Mu Sweep 2 is modeled as a piture frame magnet with a filled gap. C Three piees of passive steel shielding downstream of the dump are inluded C The first is 800 m x 280 m x 80 m The seond is 400 m x The third is 300 m x 280 m x 140 m 280 m x 280 m The PW8 Experiment hall modeled as a onrete enlosure with 18 inh thik onrete eiling walls and floor. N=l Steel N=2 N=3 N=4 N=S Copper Tungsten Soil Conrete (not used in urrently speifed geometry) X,Y,Z ARE "LAB" COORDINATES XM, YM, ZM ARE "MAGNET" COORDINATES IN PRESENT EXAMPLE THEY ARE IDENTICAL Keep these 5 lines here, always. CASIM needs the ounter KT, and needs to C know when the ounter has gone beyond it's limit KT=KT+l IF(KT.GT.10000) THEN N = 99 RETURN ENDIF Set N=O until we know if we are in some other material N=O Set M=O until we know if we are in a field region M=O C First hek the limits of the geometry and exit if outside them R = SQRT(X*X + Y*Y) IF (R.GT. RLIM) THEN N = 99 RETURN ENDIF IF (Z.LE.O.. OR. Z.GT.ZLIM) THEN N = 99 RETURN ENDIF C Set "Magnet" oordinates the same as Lab oordinates XM=X YM=Y ZM=Z C AX=ABS(X) AY=ABS(Y) Define Geometry -6-

9 C C Assume vauum everywhere N=O Define steel shielding/hole/tgt(full and half density) IF(Z.LT.200.) THEN IF(AY.LT AND. (X.LT AND.X.GE )) N=l!Steel IF(AY.LT.10.. AND. (X.LT.20.. AND.X.GE.-6.)) N=O!Hole IF(Z.GE.100.) THEN IF(AX.LT.5.. AND.AY.LT.2.5) N=3!Full density tungsten tgt IF(AX.LT.5.. AND. (Y.GE.2.5.AND.Y.LT.7.5)) THEN Half-density tungsten tgt IF(Z.LT.110.) N=3 IF(Z.GE AND.Z.LT.130.) N=3 IF(Z.GE AND.Z.LT.150.) N=3 IF(Z.GE AND.Z.LT.170.) N=3 IF(Z.GE AND.Z.LT.190.) N=3 C***** IF(AY.LT.10.. AND. (X.LT.-6.. AND.X.GE.-16.)) N=3!Tungsten below dump ENDIF C Define Selma magnet as solid steel blok IF(Z.GE AND.Z.LT.900.) THEN C***** IF(AX.LT AND.AY.LT.145.) N=l!30 m steel added on top and bottom C***** IF(AX.LT.95.. AND.AY.LT.145.) N=l!nominal SELMA dimensions IF((X.LT AND.X.GE.-95.).AND.AY.LT.145.) N=l!30 m steel on top only IF((X.LT AND.X.GE ).AND.AY.LT.145.) N=5!Extra onrete below SELMA C Define MuSweep 2 IF(Z.GE AND.Z.LT.1800.) THEN C Top/Bottom Steel IF(AX.LT AND.AX.GE.30.) THEN IF(Y.LT.35.. AND.Y.GE.-325.) N=l C East/West Steel IF(AX.LT.30.) THEN IF(AY.LT.35.) N=l!East IF(Y.LT AND.Y.GE.-325.) N=l!West C Passive Steel 1 IF(Z.GE AND.Z.LT.2700.) THEN IF(AX.LT AND.AY.LT.40.) N=l C Passive Steel 2 IF(Z.GE AND.Z.LT.3100.) THEN IF(AX.LT AND.AY.LT.70.) N=l C Passive Steel 3 IF(Z.GE AND.Z.LT.3400.) THEN IF(AX.LT AND.AY.LT.140.) N=l Roof Slab IF(X.LT.513.l.AND.X.GE.467.4) THEN IF(AY.LT.457.2) N=5 Side Walls IF(AY.GE AND.AY.LT.502.9) THEN IF(Z.LT.154.3) THEN IF(X.LT.513.l.AND.X.GE ) N=5!Upstream Side Walls ELSE IF(X.LT.513.l.AND.X.GE ) N=5!Downstream Side Walls -7-

10 C C C Floor Slabs IF(AY.LT.457.2) THEN IF(Z.LT.154.3) THEN IF(X.LT AND.X.GE ) N=5!Upstream Slab ELSEIF (Z.GE AND.Z.LT.200.) THEN IF(X.LT AND.X.GE ) N=5!Transition Slab ELSE IF(X.LT AND.X.GE ) N=5!Downstream Slab Soil Regions outside enlosure walls out to RLIM IF(AY.GE.502.9) N=4!Sides IF(AY.LT AND.X.GE.513.l) N=4!Top IF(Z.LT.154.3) THEN IF(X.LT ) N=4!Upstream below floor ELSE IF(X.LT ) N=4!Downstream below floor Speial soil region below tungsten dump for onen. model est. IF(Z.GE AND.Z.LT.200.) THEN IF(X.LT AND.X.GE ) THEN IF(AY.LT.15.) N=6!Speial soil bin below dump Speial soil region below Selma for onen. model est. IF(Z.GE AND.Z.LT.300.) THEN IF(X.LT AND.X.GE ) THEN IF(AY.LT.15.) N=7!Speial soil bin below Selma RETURN END -8-

11 Appendix 2 CASIM Input Data File The first lines hold the list of ustomized files you need to run your CASIM geometry. The two listed here are the MINIMUM you need, and should always be there. If you gave the CASIMGEOM file a ustomized name, then you need to edit that name here in plae of CASIMGEOM.FOR. Add more files as needed, add them as new lines below these two, 1 file-name per line, left-justified. CASIM.FOR E872DUMPGEOM.FOR E872DUMPGEOMVIEW.FOR E872CASPRIMAR.FOR!!!!!!!!!!!! The CASIM Input Dek information starts below this line!!!!! l.e !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! the information below is ignored by all CASIM ommand proeedures!!!!!! but is provided to list the standard parameters for materials used!!!!!! by most CASIM geometries. Copy lines below into the Input Dek above!!!!!! as needed. Do NOT opy the preeeding material ID line. The order!!!!!! in whih they are listed does not imply any assumptions within CASIM. Fe Iron Cu Copper Cu/H20 ombined, for water ooled magnet oils Brass Al Aluminum Be Berylium w Tungstun Pb Lead Soil Conrete

12 I INPUT DATA TABLE ISOTOPE DATA TABLE H3 Na22 Stars per inident partile Mean lifetimes (years) E-01 Protons per year Migration rate (ft per year) E+18 Distane to aquifer (feet) Allowed onentrations (pci per ml) Leahable atoms per star OUTPUT DATA TABLE H3 Na22 Conentrations (pci per ml) Ratio to allowed onentration OK OK Combined Ratio to EPA 4 mrem limitl 0.98 OK!All OK? H Yffi] Table 1- Single Resident Well Model spreadsheet results

13 Figure la- Cross setion through target/dump shielding region (dimensions in m)

14 >I Figure lb - Elevation view through target/dump shielding region (dimensions in m)

15 ~~~~~~~~~~~~100~~~~~~~~~~~~... 1(~ Beam-~ ~. l ~~... 1~ Plan view Cross setion Figure 2 - Tungsten target geometry (dimensions in m)

16 Figure 3 - SELMA magnet geometry (dimensions in m)

18 l ~ 300 ~ Plan View l ~ 300 ~ Elevation View Figure 5 - Muon absorber steel (dimensions in m)

20 s ro Cl.)!--<... en i::: ~ 0 '"'d i::: u Cl.) en en en 0!--< u 00 ~

21 MuSweep 2 Selma Steel Absorber 3 Plan View Ill Steel [J Conrete [J Soil ~ Tungsten Sale (meters) Figure 7a - Plan view of full geometry

22 Extra steel on top Passive Steel 1 Passive Steel 2 Passive Steel 3 Regions Used for Conentration Model Elevation View II Steel [I] Conrete D Soil ~ Tungsten Sale (meters) Figure 7b- Elevation view of full geometry

SHIELDING MATERIALS FOR HIGH-ENERGY NEUTRONS

SHIELDING MATERIALS FOR HIGH-ENERGY NEUTRONS SHELDNG MATERALS FOR HGH-ENERGY NEUTRONS Hsiao-Hua Hsu Health Physis Measurements Group Los Alamos National Laboratory Los Alamos, New Mexio, 87545 USA Abstrat We used the Monte Carlo transport ode Los