ML081610161
| ML081610161 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/24/2008 |
| From: | Tallman D Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| F8130131 | |
| Download: ML081610161 (25) | |
Text
{{#Wiki_filter:Rancho Seco Final Status Survey Summary Report March 20, 2008 Letdown Filter/Backwash Tank Room Survey Unit F8130131 Prepared By: D.A.Tallman Date: March 24, 2008 FSS n ireer Reviewed By: Date2:,_/ / LeaOiSS S ngineer Approved By: 7 Date: Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit: F8130131, Letdown Filter/Backwash Tank Room Survey Unit
Description:
Operating History: The Auxiliary Building, a reinforced concrete structure, contained the RadWaste processing and supporting systems. The building contained six main elevations. Residual radioactive material was known to be present on all levels of the interior of the building. Operating records and the HSA document several events with the potential for a release of radioactivity inside this structure. Site Characterization: Direct measurements were made of each of the interior elevation surfaces as well as the exterior surfaces of the structure. These measurements confirmed the presence of plant-derived radionuclides Direct measurements on the -20' elevation showed a mean gross activity level of 247,831 dpm/100 cm 2 and a maximum value of 10,080,000 dpm/100 cm 2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the Letdown Filter/Backwash Tank Room within the interior of the auxiliary building was determined to be a Class 1 survey unit. Survey Unit Design Information: The Survey Unit Design Parameters are presented in Table 1 below. The survey unit and measurement locations are depicted on the maps in Attachment 1. Direct measurement locations were determined using a random-start, fixed grid pattern and 68.2 m2 were scanned for 100% coverage. Samples of removable contamination were collected at each direct measurement location. The instrumentation used for the survey along with the MDC values are listed in Tables 2-1 and 2-2 in Attachment 2. Page 2 of 8 FSS Summary Report F8130131
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F8 13 Survey Unit: Class: SU Area (m2): Evaluator: DCGL (dpm/100 cm2): Area Factor: Design DCGLemc (dpm/100 cm 2): LBGR (dpm/100 cm 2): Design Sigma (dpm/100 cm 2): Type I Error: Type II Error: Predominant Nuclide: Sample Area (M2): Scan Area (m2): Scan Coverage (%): Zl-Q : Sign P: Calculated Relative Shift: Relative Shift Used: N-Value: Design N-Value + 20%: Design Min Samples N: Grid Spacing L: 0131 1 68.2 D.A.Tallman 43000 4.8 207561 21500 12035 0.05 0.05 Cs-137 4.26 68.2 100% 1.645 1.645 0.96407 1.8 1.8 13 16 16 2.0 Letdown Filter/Backwash Tank Room Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class I Default 50% DCGL Class 1 Class 1 Uses 3.0 if Relative Shift is >3 NUREG-1575 Table 5-5 Class 1 Class 1 Page 3 of 8 P FSS Summary Report F8130131
Survey Results: A total of 18 direct.measurements were made in F8130131. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. One of the scan measurements indicated areas of elevated activity. Scan activity ranged from 3297 to 91179 dpm/100 cm 2, based on a surveyor efficiency of 0.5 and no background subtracted. Samples for removable surface activity were all less than 10% of the DCGL as shown in Table 3. Removable surface activity samples were counted for alpha activity and none was detected at the MDC shown in Table 2-1 of Attachment 2. Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/100 cm F8130131 -CO001 BD F8130131-CO002BD F8130131 -CO003BD F8130131-CO004BD F8130131-C0005BD F8130131-C0006BD F8130131 -C0007BD F8130131 -C0008BD F8130131-C0009BD F8130131-CO01OBD F8130131-Co01 IBD F8130131-Cool2BD F8130131-CO013BD F8130131--Co014BD F8130131-CO015BD F8130131-CO016BD F8130131--Co017BD F8130131--Co018BD Mean: Median: Standard Deviation: Range: 2173 -1499 4596 1411 2090 1790 1696 2314 1935 2002 2225 2101 2137 2272 1878 3408 2308 2407 2236 2119 729 .1411-4596 Page 4 of 8 FSS Summary Report F8130131
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2) F8130131 COOOI SM F8130131 C0002SM F8130131CO003SM F8130131 C0004SM F8130131 C0005SM F8130131 C0006SM F8130131 C0007SM F8130131 C0008SM F8130131 C0009SM F8130131CO010SM F8130131CO01ISM F8130131 Co012SM F8130131 Co013SM F8130131C0014SM F8130131Co015SM F8130131CO016SM F8130131 Co017SM .F8130131 Co018SM Mean: Median: Standard Deviation: Ranqe: 1.64 6.8 32.63 18.42 26.17 -0.95 14.55 2.93 5.51 -3.53 0.34 4.22 4.22 2.93 -0.95 15.84 -3.53 1.64 7.16 3.57 10.26 -3.53 to 32.63 Page 5 of 8 FSS Summary Report F8130131
Survey Unit Data Assessment: The survey design required 18 direct measurements for the Sign Test. The critical value and the results of the Sign Test are presented in Table 4. The sample mean and median values were less than the DCGL. The sample standard deviation was less than the design standard deviation so no additional samples were required. Page 6 of 8 FSS Summary Report F8130131
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm2): N/A Ambient Background Used (dpm/100 cm2): N/A Average Ambient BKG 0 Actual Direct Measurements (N): 18 Median (dpm/100 cm 2): 2119 Mean (dpm/100 cm2): 2236 Direct Measurement Standard Deviation 729 (dpm/100 cm 2): Total Standard Deviation (dpm/100 cm 2): 729 Based on samples and backgrounds. Maximum (dpm/100 cm 2): 4596 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 18 S+ Value: 18 Critical Value: 12 Sufficient Samples Collected: Yes Maximum Value < DCGL: Yes Median Value < DCGL: Yes Mean Value < DCGL: Yes Maximum Value < DCGLemc: Yes Class I Total Standard Deviation <= Sigma: Yes Pass the Sign Test? Yes Reject the Null Hypothesis? Yes Does the Survey Unit Pass All Criteria? Yes Page 7 of 8 FSS Summary Report F8130131
Survey Unit Investigations and Results: One investigation (Penetration Scan P0011) was required and the results are reported in. The EMC unity rule was not exceeded as shown in Table 3-1. ALARA Statement: As stated in Chapter 4 of the LTP, as long as the residual activity within the survey unit is less than the DCGL (i.e. the survey unit average activity is less than the DCGL and the EMC criterion has been met), the ALARA criterion has been met. Changes in Initial Survey Unit Assumptions: The survey unit was designed as a Class 1 structure survey and the sample results are consistent with that classification. The variability of the, survey results was less than charterization data used for survey design. One potential area of elevated activity was detected and evaluated as shown in Attachment 3 demonstrating that the EMC criterion was met.
== Conclusion:== The FSS of this survey unit was properly designed as a Class I survey based on Table 5-4 of the LTP. The required number of direct measurements was made and the scan coverage met the requirement of Table 5-6 of the LTP. No direct measurements exceeded the DCGL of 43000 dpm/100 cm2 and none of theremovable surface activity measurements exceeded 10% of the DCGL. The investigation required was performed and evaluated as shown in Attachment 3 The direct measurement data support rejection of the null hypothesis, providing high confidence that the survey unit satisfied the release criteria and that the data quality objectives were met. It is concluded that survey unit F8130131 meets the release criteria of IOCFR20.1402. Page 8 of 8 FSS Summary Report F8130131 Maps March 20, 2008 Survey Unit F8130131
(a IN) 0 i Lower Cubicle Ceiling 4.6 M2 Upper Cubicle Floor wal And Wall Tops 7.7 m2 0 I. r Z A uox. s /, Dmi Room 13 C_gJinq. -cJ Omkorro; 1 7.7 m2 KEY PLANS (Not To Scale) Lower Cubicle Floor 4.8 m2 \\(7~ 00 wO 4 V1 South Wall .12.6 m2 (Includes Door Facings) Upper Cubicle. Door Facing Delail KoorFacing D~w West Wall North Wall 9.2 M2 11.9 m2 9.7 m2 SCALE METERS U-11L1771 DISTRICT SURVEY LOCATION MAP LETDOWN FILTER/BACKWASH TANK ROOM SURFACE AREA ESTIMATE F81 30131 -M1 8i300lO2r, SHEET 1 of 1 IC F1i.F:8 HILL
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0 P7,5 .*rrkj*" KEY PLANS (Not To Scale) " West Wall North Wall 00 SCALE METERS 91 .RAMH HO MWTCPI UT11--I DIS-TRICT SURVEY LOCATION MAP LETDOWN FILTER/BACKWASH TANK ROOM BETA DIRECT/REMOVABLE ACTIVITY F81 30131 -M.2 fB3flO,2a SiiEEr 2 0f4 1C HILL -JFL
0 t12 ~19 ~ I. ~ T ~ ,/.>UX "[ BLDG,'/ KEY PLANS (Not To Scale) I. East Wall 00 I SCALE METERS
- )mu 5U[VLY LU(YAIIUN MAP LETDOWN FILTER/BACKWASH TANK ROOM BETA DIRECT/REMOVABLE ACTIVITY F81 30131 -M2 F
~SHlEET3e.4 i 'jTULi' DISTRICT
0 -V 4 4 4 14 KEY PLANS (Not To Scale) Top of Upper Cubicle Floor yva,. 7 N 1L 11'-6" Room 13 Ceilin V4,4 i. 4I 4. 4 ~4 S 4 4 4 4 .5 '171 00 Lower Cubicle Floor SCALE METERS Lower Cubicle Ceiling UTILFYb"Th C SURVEY LOCATION MAP LETDOWN FILTER/BACKWASH TANK ROOM BETA DIRECT/REMOVABLE ACTIVITY F81 30131 -M2 .F 3 SHEEr 4 o*4 TCHILL
0 Lower Cubicle Floor 4.8 m 2 Lower Cubicle Ceiling 4.6 m2 AUX. BLDG I. 114 KEY PLANS (Not 1o Scale) Upper Cubicle Floor wails And'Wall Tops Room 13 Ceiling 7.7 M2 7.7 m2 00 W~ West Wail 9.2 ml 11.9 M2 0 ME1ER SCALE METERS East Wall 9.7 m2 SURVEY LOCATION MAP 'LETDOWN FILTER/BACKWASH TANK ROOM 0 SCmNm I BETA SCANS UTILIT-r DISTRICT IF8 1 301 31 M3 IFl.E 8130002a SHEEI I of 1 1 C HILL
CD 0 00:: SLower Cubicle Ceilirng 4.6 ml Rl* e I rSol Corridor KEY PLANS (Not 1o Scale) I Lower Cubicle Floor 4.8 ml Upper Cubicle Floor wait. And Wall Tops Room 13 Ceiling 7.7 m 2 7.7m 2 YN 00 U.) U.) 7/ 14 I: i. ii \\! I.. : South )**l 12.6 ma (includes Door Facings) Upper Cubicle Door Facing Delail West Wal 9.2 m2 North Wall East Wall 9.7 m2 11.9 m, Door Facing Detail a a SMUD SACRAMEN~TO MUNI IAL UT Lr( Dl-TRrCT SURVEY LOCATION MAP LETDOWN FILTER/BACKWASH TANK ROOM JUNCTURE SCANS F81 30131 -M4 FLF63O SiEEY 1 of 1 TC HILL
0 Lowor Cubicle Floor 4.8 m2. Room 13 Ceiling 7.7 ml
- // *.
km.,ý4/ RU 15 7;* ___ Gcwridor KEY PLANS (Not To Scale) Top dl Lower Cubicle Ceiling Upper Cubicle Floor wails 4.6 m2 And Wall Tops -7.7 m*2 00 wa I A~ 0.. K East Wall 9.7 M2 N,: J::41it ,:.]- South Wall 12.6 m,2 (Includes Door Facings) Upper Cubicle Door Faring Detail Door Facing Detail West Wagl North Wall 9.2 mr 11.9 m 2 0 M ETR SCALE METERS SURVEY LOCATION MAP LETDOWN FILTER/BACKWASH TANK. ROOM o SMUPENETRATION SCANS SAw.CAILNtO IMUNICF,`L UTILITY DiSTRICT F8130131-M5 . [ 3- ?.-L: s lol1. TC HILL Instrumentation March 20, 2008 Survey Unit F8130131
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No. Model; Serial No. (dpm/100 cm 2) (dpm/100 cm 2 ) M2350; 180733 43-98B; 148638. 590 1070 M2350; 180733 43-98B; 1486382 930 1680 M2350; 180733 43-98B; 1486383 1400 2520 M2350; 180733 43-98B; 1486384 550 990 M2350; 180733 43-94; 1486205 350 610 M2350; 142515 43-68B; 148453 433 1033 M2350; 180738 43-68/5B; 148942 433 1033 M2350; 193700 43-116-1B; 216072 7 796 3258 M2350; 193700 43-116-1B; 216073 6 491 739 M2350; 180738 43-116-1B; 2160737 796 3258 Tennelec; 0401171 N/A 5.88 dpm a, 11.71 dpmf3 N/A Penetration - 2" - concrete 2 Penetration - 3" - concrete 3 Penetration - 4" - concrete 4 Penetration - 3" - metal 5 Penetration - 1"- concrete 6 Juncture - concrete 7 Structure /Penetration - 4"- 14" - concrete Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm2) Investigation Criteria - Direct 207561 Investigation Criteria - Scan 43000 A DCGLW 43000 DCGLEMC 207561 A Investigation Level set at DCGLw within the survey instruction. Page 2 of 2 Att. 2 Instrumentation F8130131 Investigation March 20, 2008 Survey Unit F8130131 (none required)
Table 3-1 Survey Unit Investigation Investigation Initial Value Investigation Elevated Area Investigation DCGLermc Grid Leves Iniia Value Result DCGLemc Result Unity Level (cpm) (cpm) (cpm) Area (i 2) Factor (dpm/lOOcm2) Fraction P001 1 3180 6731 6731 0.09 146 6,281,162 91180 0.0142 DCGL = SU Mean = Survey Unit Remainder 43,000. 2236 0.052 EMC Unity Sum 0.0662 Page 2 of 2 Att. 3 Investigation F8130131 Data Assessment March 20, 2008 Survey Unit F8130131
F8130131 Gross Activity Sample Results Quantile Plot DCGL 43000 dpm/1 00cm2 5,000 4,500 4,000 S3,500 -~ U.2,500 >2119 CD~ I ~ ~~1,5000; = 0 20 40 60 80 100 -Percentile Direct Measurements (dpm/l1O00cm2) median - - -75th Percentile. 50th Percentile
0Q F8130131 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmllO0cm0= 5000 4500 -- 4422 4000-o 3500 - C
- r. 3000 E4L2500
- 2000 -
0 P> 0.oo EnŽ1500 0 1000 Soo o0 500 Measurement Locations 00 Gross Activity - Average - "+3StDev" - "-3StDev"
(t* Cd, 00 F81 30131 -Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm-11 U-C_ 0 10 9 8 7 6 5 4 3 2 1 0 (NJ C?) (NJ Bins - Upper End Value (dpm/100cm2)}}