ML20101C345

Provides Radiation Survey Data Taken by Scientific Ecology During side-by-side Measurements W/Representatives from Oak Ridge Inst for Science & Education in Sept 1995 & Jan 1996

ML20101C345
Person / Time
Site:	Fort Saint Vrain
Issue date:	03/07/1996
From:	Borst F PUBLIC SERVICE CO. OF COLORADO
To:	Weber M NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
References
P-96014, NUDOCS 9603180241
Download: ML20101C345 (18)

Text

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16805 WCR 191/2; Platteville, Colorado March 7,1996 Fort St. Vrain P-96014 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 ATTN: Mr. Michael F. Weber, Chief

, Decommissioning and

.tegulatory Issues Branch Docket No. 50-267

SUBJECT:

Final Survey Plan for Site Release, Side-By-Side Measurement Data

REFERENCE:

PSCo letter, Borst to Weber, dated November 15,1995 (P-95102);

" Final Survey Plan for Site Release, Supplemental Information"

Dear Mr. Weber:

This letter provides radiation survey data taken by the Scientific Ecology Group (SEG),

one of Public Service Company of Colorado's decommissioning contractors, during side-  ;

by-side measurements with representatives from the Oak Ridge Institute for Wience and Education (ORISE). This data was taken during two separate NRC/OR15E on-site inspections at Fort St. Vrain, in September 1995, and in January 1996, and is provided in response to a request from Messrs. Clayton Pittiglio and David Fauver of your staff.

SEG's survey data and supporting explanatory information is provided in three attadeents, as follows:

Attachment 1: Seotember 1995 Survey Data The referenced letter provided side-by-side measurement data taken during the September 27,1995, NRC/ORISE inspection from three areas: the Battery Room, the Electrical Warehouse, and the Reactor Building Ixvel 3 Resin Changeout

, Area. The data reflected gross measurements that had not been corrected for background.

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9603180241 960307 PDR ADOCK 05000267 W PDR 100r70 t q\

P-96014 March 7,1996 Page 2 To identify background activity (as discussed in Attachment 3), SEG collected local area background (shielded) measurements subsequent to the ORISE l

inspection. The locations used during side-by-side comparison measurements were used for background measurements in the Battery Room and Electrical Warehouse; however, the Reactor Building level 3 Resin Changeout Area was not available for shielded measurements and background correction has not been

made for this area.

Att. chment 1 includes gross measurements for all three areas as submitted in the i

referenced letter and, in addition, net total surface activity measurements are provided for the Battery Room and the Electrical Warehouse, corrected for both the local area background and specific material background. Calculational details

! for converting gross measurement results to net total surface activity values are also provided.

Attachment 2: January 1996 Survev Data ,

Attachment 2 includes survey data taken during the January 22-25, 1996, inspection, for four amas: the Battery Room, the Lube Oil Room, a Reactor Building location at about 2500 dpm/100 cm2, and a Reactor Building location at about 5000 dpm/100 cm2. This data has been analyzed to correct gross measurement results for material background and local area background, using Battery Room measurements as the material background.

Attachm-nt 3: behround Determination l Attachment 3 is a discussion of the two-component background approach used at Fort St. Vrain to account for background during total surface activity measurements.

To facilitate our review of the side-by-side measurements, PSCo requests copies of ORISE's measurement data, both gross measurements and net activity results after j correcting for background. It is our understanding that this information will be included I

in the NRC's inspection reports.

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P-96014 March 7,1996 Page 3 If you have any questions regarding this information, please contact Mr. M. H. Holmes at (303) 620-1701.

Sincerely, hk)v'cl YSW Frederi J. Borst Decommissioning Program Director FJB/SWC Attachments cc: w/ attachments Regional Administrator, Region IV Mr. Robert M. Quillin, Director  ;

l Radiation Control Division  !

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ATTACHMENT 1 TO P-96014 l

SEPTEMBER 1995 SURVEY DATA l

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TURBINE BUILDING - LEVEL 5 BATTERY ROOM - CONCRETE FLOOR (C) (C+(60!ts)) (Rb) ((Am)*(E)*(a/100)) (Rb)+((Am)*(E)*(a/100)) Activity Activity Sample Unshielded Unshielded Shielded Material Total Bkgd Result Result Result Result Result Bkgd Correction (Gross) (Net)

(Concrete) Previously Reported 2

(ets/15 sec/125cm ) (cpm /125cm2) (cpm /125cm2 ) (cpm /125cm2 ) (cpm /125cm2 ) (dpm/100cm2) (dpm/100cm2 )

! 1 148.0 592.0 364.0 196.5 560.5 2310 123 2 155.0 620.0 348.0 196.5 544.5 2420 294 3 143.0 572.0 356.0 196.5 552.5 2232 76 4 137.0 548.0 376.0 196.5 572.5 2139 -%

5 154.0 616.0 360.0 196.5 556.5 2404 232 6 152.0 608.0 396.0 196.5 592.5 2373 60 7 145.0 580.0 368.0 196.5 564.5 2263 60 8 155.0 620.0 428.0 196.5 624.5 2420 -18 9 135.0 540.0 380.0 196.5 576.5 2107 -143 l

10 174.0 696.0 408.0 196.5 604.5 2716 357 l Mean: 2338 95 Countine Parameters:

l (C) = integrated gross counts l (ts) = sample counting interval,15 seconds l (Rb) = local area background count rate l (Am) = responsa of the instrument to the material,767 dpm/100cm2 (E) = counting efficiency,0.205 (a) = area of the detector,125 cm 2 l

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ELECTRICAL WAREHOUSE CONCRETE FLOOR (C) (C+(60/ts)) (Rb) ((Am)*(E)*(a/100)) (Rb)+(( Am)*(E)*(a/lo0)) Activity Activity Sample Unshielded Unshielded Shielded Material Total Bkgd Result Result Result Result Result Bkgd Correction (Gross) (Net)

(Concrete) (Previously Reported) 2 (cts /15 sec/125cm ) (cpm /125cm2 ) (cpm /125cm2 ) (cpm /125cm2) (cpm /125cm2) (dpm'100cm2 ) (dpm/l(XAm2 )

1 205.0 820.0 552.0 196.5 748.5 3200 279

2 194.0 776.0 524.0 196.5 720.5 3028 216 3 202.0 808.0 468.0 196.5 664.5 3153 560

4 212.0 848.0 560.0 196.5 756.5 3309 357 i

5 201.0 804.0 540.0 196.5 736.5 3138 263 6 189.0 756.0 420.0 196.5 616.5 2950 544 l 7 188.0 752.0 444.0 196.5 640.5 2935 435 8 172.0 688.0 492.0 196.5 688.5 2685 -2 l

l 9 158.0 632.0 504.0 196.5 700.5 2466 -267 10 188.0 752.0 476.0 196.5 672.5 2935 310 11 183.0 732.0 492.0 196.5 688.5 2857 170 12 187.0 748.0 428.0 196.5 624.5 2919 482 l

13 187.0 748.0 516.0 196.5 712.5 2919 138 14 184.0 736.0 476.0 196.5 672.5 2872 248 15 176.0 7N.0 476.0 196.5 672.5 2747 123 16 192.0 768.0 484.0 196.5 680.5 2997 341 17 183.0 732.0 524.0 196.5 720.5 2857 45 l 18 169.0 676.0 528.0 196.5 724.5 2638 -189 19 168.0 672.0 5M.0 196.5 700.5 2622 -111 20 168.0 672.0 464.0 196.5 660.5 2622 45 Mean: 2892 199 Counting Parameters:

(C) = integrated gross counts (ts) = sample counting interval,15 seconds (Rb) = local area background count rate (Am) = response of the instrument to the material,767 dpin/100cm2 (E) = counting efficiency, 0.205 (a) = area of the detector,125 cm 2

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REACTOR BUILDING - LEVEL 3 RESIN CHANGE OUT AREA - CONCRETE FLOOR l Location # Sample # Count Time Counts Counts Activity (sec) (cts /15sec/125cm )

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RESIN CHANGE OUT AREA 2 15 1008 4032 15735 RESIN CHANGE OUT AREA 3 15 l 400 1600 6244 RESIN CHANGE OUT AREA 4 15 311 1244 4855 l RESIN CHANGE OUT AREA 5 15 366 1464 5713 RESIN CHANGE Otf7 AREA 6 15 419 1676 6540 1 1

RESIN CHANGE DUT AREA 7 15 378 1512 5900 RESIN CHANGE OUT AREA 8 15 1481 5924 23118 RESIN CHANGE OUT AREA 9 15 465 1860 7259 RESIN CHANGE OUT AREA 10 15 337 1348 5260 RESIN CHANGE OUT AREA 11 15 467 1868 7290 R'ESIN CHANGE OUT AREA 12 15

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1350 5400 21073 RESIN CHANGE OUT AREA 16 15 662 2648 10334 RESIN CHANGE OUT AREA 17 15 335 1340 5229 RESIN CHANGE OUT AREA 18 15 1018 4072 15891 RESIN CHANGE OUT AREA 19 15 665 2660 10380 RESIN CHANGE OUT AREA 20 15 323 1292 5042 NOTES

1) Instrument Type: Ludlum Model 2350 Data Logger Serial #95359

2) Detector Model Number: 43-68B Gas Flow Proportional Counter - Serial #PR092525

3) Instrument Efficiency: .205

4) Detector Area: 125cm2

! 5) Background : No background value applied 1 j 5) Technician: Declan Detrick j 7) Survey Date: 09/27/95 b l

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ATTACHMENT 2 TO P-96014  :

1 JANUARY 1996 SURVEY DATA i

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,SEG MEASUREMENT COMPARISON SEG Team 1

• Shelded Meas. Shielded Meas. Shielded Meas. Unshielded Meas. Unshielded Meas.

• Unshielded Meas.

Download 999 LAB (com/125cm2) LAB (epm /100cm2) LAB (dpm/100cm2) (Gress epm /125cm2) (Gross dpm/100cm2) (Mat 1 Bkod, dpm/100cm2)

Battery Room 416 332 8 1505 9 684 0 2476 0 933 9 (Background) 440 352 0 1592 8 664 0 2403 6 861 5 376 300 8 1361.1 6360 2302 3 760 2 432 345 6 1563 8 $88 0 2128 5 586 4 492 3936 1781 0 696 0 25195 977.4 400 320 0 1448 0 500 0 1810 0 267 9 588 0 2128 5 586 4 -

668 0 24181 876 0 632 0 2287 8 745 7 620 0 2244 3 702 3 (

Std Dev 39 7 31 7 143 6 58 1 210 3 210 3 Mean 426 0 340 8 15421 627 6 22719 729 8 Emciency 0221

• %Cotff of Var 9 31 9 26 l

SEG Team 2

• Shielded Meas Shielded Meas Shielded fAeas. Unshielded Meas Unshielded Meas.

• Unshielded Meas Download 1008 LAB (cpm /125cm2) LAB (cpm /100cm2) LABitpm/100cm2) (Gross cpm /125am2) (Gross dpm/100cm2) (MatI Bkgd dpm/100cm2)

Battery Room d24 339 2 1378 9 684 0 2224 4 737 1 l (Background) 536 428 8 1743 1 724 0 2354 5 867 2 460 368 0 1495 9 640 0 2081 3 594 0 432 345 6 1404 9 720 0 2341 5 854 2

! 460 3680 1495 9 576 0 1873 2 385 9 432 345 6 14049 816 0 2653 7 1166 4 j

776 0 2523 6 1036 3 l

712 0 2315 4 828 2 l 808 0 2627 6 1140 4 l 6640 2159 3 6721 Std Dev 41 5 33 2 134 9 75 4 245 1 245 1 Mean 457 3 365 9 1487.3 712 0 2315 4 828 2 Emcien~/ 0 246

• %Creff of Var 9 07 1058 lMean Mat'l Bked 779.0 ORISE Shielded Meas. Shielded Meas. Shielded Meas. Unshelded Meas Unshielded Meas Unshielded Meas Battery Room LAB (cpm /125cm2) LAB (cpm /100cm2) LAB (dpm/100cm2) (Gross cpm /125cm2) (Gross opm/100cm2) (NET dpm/100cm2)

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NOTES.

• LAB = Local Area Background (Sheelded Measurement)

• 125 cm2 = Detector Area A * % Coemcient of Vanability = Standard Devation / Mean 1

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• The above data sets were corrected only for effcefty, detector area, and LAB Net results def:ne the maten91 background j

• The Mean Matenal Background was determined from the above data sets and used to correct subsequent data sets 1

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,SEG MEASUREMENT COMPARISON l

i SEG Team 1 Shielded Meas. Shielded Meas. Shielded Meas. Unshielded Meas. Unshielded Meas. " Net Result l Download 999 LAB (cpm /125cm2) LAB (com/100cm2) LAB (dpm/100cm2) (Gross cpm /125cm2) (Gross dpm/100cm2) (dpm/100cm2)

Lube Oil Room 384 307.2 1390 0 524 0 1896 8 -298 7 332 265 6 12018 608 0 22009 53 316 252 8 1143 9 600 0 2171 9 -236 464 371 2 1679 6 564 0 2114 0 -81 5 444 355 2 1607 2 624 0 2258 8 63 3 408 3264 14769 528 0 1911 3 -264 3 600 0 2171.9 -23 6 536 0 1940.3 255 3 616 0 2229 9 34 3 ,

476 0 1723 1 -472 6 )

Std Dev 59 3 47 4 214 7 49 8 180 4 180 4 Mean 391.3 313 1 1416 6 5696 2061 9 -1337 l Emciency 0221 l

%Coeff of Var 15 15 8 75 SEG Team 2 Shielded Meas Shielded Meas. Shielded Meas. Unshielded Meas Unshielded Meas.

• Net Result Download 1008 LABIcpm/125cm2) LAB (epm /100cm2) LAB (dpm/100cm2) (Gross epm /125cm2) (Gross dpm/100cm2) (dom /100cm2)

Lube Oil Room 452 3616 1469 9 612 0 1990.2 228 3 368 294 4 1196 7 716 0 2328 5 109 9 460 364 0 1561 0 644 0 2094 3 -124 2 436 348 8 1417 9 608 0 1977 2 241 3 396 316 3 12878 672 0 2185 4 -33 2 524 419 2 1704 1 7560 2458 5 240 0 f 668 0 2172 4 -46 2 612 0 1990 2 -228 3 636 0 2068 3 150 3 644 0 2094 3 -124 2 Std Dev 56 4 451 183 3 48 1 1566 156 6 Mean 442 7 354 1 1439 6 6568 2135 9 -82 6 Efficiency 0 246

%Coeff of Var 12 74 7 33 ORISE Shielded Meas Shielded Meas. Shielded Meas Unshielded Meas Unshielded Meas. Net Result L .,e Oil Room LAB (com/125cm2) LAB (cpm /100cm2) LAB (dom /100cm2) (Gross cpm /125cm2) (Gross dpm/100cm2) (dpm/100cm2)

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%Coeff of Var "NUIL Net Result = Unshielded Meas (Uross Opm/100cm2) - Shiek ed Meas (LAB. dpm/100cm2)- Mean Mati 5kgd(dprn/100cm2) 1 i

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,SEG MEASUREMENT COMPARISON l i

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SEG Team 1 Sheided Meas. Shielded Meas. Shielded Meas. Unshielded Meas. Unshielded Meas. ' Net Result  ;

Download 993 LAB (cpm /125cm2) LAB (epm /100cm2) LAB {dpm/100cm2) (Gross epm /125cm2) (Gross dpm/100cm2) (dpm/100cm2) 468

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Rx Bide . #2600 374 4 1694 1 1364 0 49376 2370 3 i 468 374 4 1694 1 1264 0 45756 2008 4 480 3840 1737 6 1344 0 4865 2 2297 9 424 339 2 1534 8 1340 0 4850 7 2283 5 576 460 8 2085 1 1296 0 4691 4 2124 2 548 438 4 1983 7 1264 0 4575 6 2008 4 1356 0 49086 2341 4 1784 0 4648 0 2080 7 l

1320 0 4778 3 2211.1 l 1338 0 4836 2 22690 Std Dev l

$6 7 45 4 205 3 37.3 134 9 134 9

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Mean 494 0 395 2 1788 2 1316 8 4766 7 2199 5 l Emciency 0221 j

%Coeff of Var 11 48 2 83

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SEG Team 2 Sh#elded Meas Shielded Meas Shielded Meas. Unshielded Meas Unshielded Meas.

• Net Result Download 1008 LAB (cpm /125cm2) LAB (cprrv100cm2) LABIdpm/100cm2) (Gross epm /125cm2) (Gross dpm/100cm2) (dpm/100cm1 .,

Rr Bldg . #2500 528 422 4 1717 1 1336 0 4344 7 1948 4 1 480 384 0 1561 0 1464 0 4761 0 2364 7 l 544 435 2 1769 1 1560 0 5073 2 2676 8 484 387 ? 1574 0 1400 0 4578 9 21825 464 371 2 1508 9 1380 0 4487 8 2091 5 484 387 2 1574 0 1620 0 5268 3 2872 0 1544 0 5021 1 2624 8 1564 0 5086 2 2689 9 1584 0 5151 2 2754 9 1524 0 4956 1 2559 8 Std Dev 31 3 25 0 101 7 95 9 311 7 311 7 Mean 497.3 397 9 1617.3 1498 4 4872 8 2476 5 l Efficsency 0 246

%Coeff of Var 6 29 6 40 l

ORISE Shielded Meas Shielded Meas. Snielded Meas. Unshielded Meas. Unshielded Meas Net Resuit Rx Bldg.#2500 LAB (com/125cm2) LAB (cpm /100cm2) LAB (dpm/100cm2) (Gross epm /125cm2) (Gross dpm/100cm2) (dpm/100cm2) i i

I Std Dev Mean Effoency

%Coeff of Var

• NOTE; Net Result = Unanielded Meas (Gross opm/100cm2) . Sneided Meas (LAB, dpm/100cm2) . Mean Mat'l Bkgdtdpm/100cm2) l 1

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. SEG MEASUREMENT COMPARISON '

SEG Team 1_ Shielded Meas. Sheced Meas. Shielded Meas. Unshielded Meas. Unshielded Meas.

• Net Result Download 999 LAB (cpm /125cm2) LAB (cpm /100cm2) LAB (dpm/100cm2) (Gross epm /125cm2) (Gross dpm/100cm2) (dpm/100cm2)

Rx Bide . #6000 488 390 4 1766 5 18080 6544 8 3972 8 488 390 4 - 17665 19280 6979 2 44071 468 374 4 1694 1 2000 0 7239 8 4667 8 468 374 4 1694 1 19680 7124 0 4551.9 520 416 0 18824 1864 0 e7475 4175 5 540 432 0 1954 8 1800 0 6544 8 39728 2040 0 73846 4812 6 1644 0 6675 1 4103 1 2024 0 7326 7 4754 7

_ 1796 0 6501 4 3929 3 Std Dev 29 0 23 2 105 0 95 4 345 4 345 4 Avg LAB 495 3 396 3 1793 1 19080 6906 8 4334 7 EN 0 221

%Coeff of Var 5 85 5 00 4

SEG Team 2 Shielded Meas Sn$ded Meas Shielded Meas Unshielded Meas Unshielded Meas

• Net Result Download 1008 LAB (cpm!125cm2) L ABrepm/1oucm., u ,w dpm/100cm2) (Gross epm /125cm2) (Gmss dpm/100cm2) (dpmM00cm2)

Rx Bldg.#5000 488 390 4 15870 2036 0 6621 1 4005 8 592 473 6 1925 2 2240 0 7284 6 4669 3 636 508 8 2068 3 2000 0 6504 1 38888 592 473 6 1925 2 2128 0 6920 3 4305 0 468 374 4 1522 0 2152 0 6998 4 4383 1 612 489 6 1990 2 2060 0 6699 2 4083 9 2100 0 6829 3 4214 0 2128 0 6920 3 4305 0 2092 0 6603 3 4188 0 2060 0 6699 2 4083 9 Std Dev 69 3 55 5 225 5 67 7 220 1 220 1 Avg LAB $64 7 451 7 1836 3 2099 6 6828 0 4212 7 EN 0 246

%Coeff of Var 12 28 3 22 o

ORISE Snielded Meas shielded Meas. Snielded Meas Unshielded Meas. Unshielded Meas Net Result Rx Bldg #5000 LAB (cpm /125cm2) LAB (com/100cm2) LABIdpm/100cm2) (Gross epm /125cm2) (Gross dpm/100cm2) (dpm/100cm2)

Std Dev Mean Effcency

%Coeff of Var i

• NOTE: Net Resutt = Unshielded Meas (Gross opm/100cm2)- Sh@ded Meas.(L.AB OprrV100cm2) Mean Mat'l Bkga(aprrv100cm2) l l

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ATTACHMENT 3 TO P-96014 i

BACKGROUND DETERMINATION l l

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i l Background Determination for Total Surface Activity Measurements

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l Measurements were collected using a Ludlum Model 2350 Data Logger (M2350) coupled to l

an LMI 43-68 gas flow proportional detector (125 cm )2 operated at the alpha-plus-beta I voltage.

l A minimum of 30 measurement locations were selected for each of the materials used to evaluate the response of the instrument. At each measurement location, a scan survey was performed within 1/2 inch from the surface to identify any discrete area of elevated activity.

Shielded and unshielded total surface activity measurements were collected on contact with the surface using a counting time of at least 30 seconds. The shield used for these l measurements has a nominal density thickness of 300 mg/cm 2 The shielded measurements (local area background) served to define the contribution to the observed response from the instrument background, the detected portion of the gamma component from the material, and '

the contribution from other local and cosmic influences. The shielded response was then subtracted from the unshielded response to define the characteristic response of the instrument to the surface of the material. The net response of the instrument was converted to standard units of surface activity (dpm/100cm2 ) in accordance with FSV-SC-FRS-I-110. Additional description of this approach, and the method for application of this value is described in the following section.

Two-Component Background Correction for Total Surface Activity This approach for background correction considers the contribution from two major components of background. The first of these components account for the response of the instrument due primarily to gamma radiation. This includes the gamma response due to the material being measured, other local influences due to gamma response from materials not l

directly under the detector and from cosmic radiation. This component also includes the small contribut.on from the instrument noise of the detection system. The second component

, of the backgrc und considers the response of the instrument to beta radiation emitted from the j surface of the material. This response is expressed in units of dpm/100cm2 in order that the response can be universally applied during final survey using appropriate corrections for detector area and detection efficiency.

To obtain net measurement results for total surface activity during final survey, several shielded measurements are collected from surfaces to be evaluated during the survey and the mean is calculated. This mean, which represents the instrument backgiound for the detection system and the response of the detection system to local area influences as described above, is expressed in units of counts per minute (cpm) per detector area.

To account for the second component of the background correction, the characteristic response of the instrument to the material as defined above is converted from units of activity (dpm/100cm2 ) nto units of counts per minute per detector area. This is done by applying the counting efficiency of the instrument and correcting for the area of the detector.

l These two components of background are then sununed, and subtracted from the gross measurement result to obtain net counts per detector area. Net activity, in standard reporting units of dpm/100cm2 , is obtained as follows:

y 3

[* * *

~

l , ,

2' 100))

a\

sel100,1 l Where:

A = net total surface activity (dpm/100 cm2),

C = integrated gross counts (counts),

t, = sample counting interval (sec),

R. = local area background count rate in counts per minute collected using a detector shield of at least 300 mg/cm 2(cpm / detector area),

A, = characteristic response of the instrument to the surface of the j material (dpm/100 cm2 ),

l

! E = efficiency of the survey instrument (c/d), and

a = detector area (cm2 ),

l l

l l

l l

1

.