ML082620166
| ML082620166 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 07/03/2008 |
| From: | Stein M Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| F8130721, MPC&D 08-064 | |
| Download: ML082620166 (29) | |
Text
Rancho Seco Final Status Survey Summary Report July 3, 2008 East Heat Removal Cooler Room Between Columns 9.2 and 9.7, Room 051 Upper Walls and Ceiling Survey Unit F8130721 Prepared By:__ _ __ _ Date: FSS Engineer Reviewed Y- Date:"42&.
Lead FSS Engineer Approved By: 7 Date: 7- -Dismantlem/ndt Superintendent, Radiological FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit: F8130721, East Heat Removal CoolerRoom Between Columns 9.2 and 9.7, Room 051 Upper Walls and Ceiling Survey Unit
Description:
Operating History: The East Heat Removal Cooler Room is located on the -20' elevation of the Auxiliary Building.
The Auxiliary Building is a reinforced concrete structure that, during power operations, contained the Radwaste processing and supporting systems.The building has six main elevations.
Residual levels of surface radioactivity were detected on all interior elevations 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 taken on each interior elevation of the Auxiliary Building.
These measurements confirmed the presence of plant-derived radionuclides.
Direct measurements taken on the -20' elevation, showed a mean gross activity level of 247,831 dpm/1 00 cm 2 and a maximum value of 10,080,000 dpm/1 00 cm 2.Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the interior surfaces of the Auxiliary Building were determined primarily to be a Class 1 for the floors and lower walls (bottom 2 meters of the walls), and Class 2 for the upper walls and ceiling. Inside the East Heat Removal Cooler Room there were a number of areas on the upper walls and ceiling where the gross surface activity levels were higher than the DCGL prior to remediation.
Therefore, a Class 1 final status survey was performed on the upper walls and ceiling of the East Heat Removal Cooler Room Between Columns 9.2 and 9.7, Room 051.HSA Events: HSA Report pg. 63.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 220 m 2 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 9 FSS Summary Report F8130721 Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: Survey Unit: Class: SU Area (m2): Evaluator:
DCGL (dpm/100 cm 2): 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 (m 2): Scan Area (M 2): Scan Coverage (%): Sign P: Calculated Relative Shift: Relative Shift Used: N-Value: Design N-Value + 20%: Design Min Samples N: Grid Spacing L: F813 0721 1 220 Michael Stein 43000 3.6 154800 21500 12035 0.05 0.05 Cs-137 6.9 220 100%1.645 1.645 0.955435 1.7 1.7 14 17 32 2.6 East Heat Removal Cooler Room Between Columns 9.2 and 9.7, Room 051 Upper Walls and Ceiling Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class I Default = 50% DCGL Class 1 Class I Uses 3.0 if Relative Shift is>3 NUREG-1575 Table 5-5 Class I Class 1 Page 3 of 9 FSS Summary Report F8130721 Survey Results: A total of 32 direct measurements were made in F8130721.
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 beta scan measurements indicated an area of elevated activity.
Beta scan activity ranged from 2,490 to 171,029 dpm/l 00 cm 2 , based on a surveyor efficiency of 0.5 and no background subtracted.
None of the gamma scan measurements indicated areas of elevated activity.
Only one of the gamma scan measurements detected activity due to plant operations at 241 dpm/100 cm 2 Cs-137. The MDCs for the gamma scan measurements were 292 to 432 dpm/l100 cm 2 for Co-60 and 280 to 397 dpm/100 cm 2 for Cs-137. Scan measurement locations for both beta and gamma emissions are identified in Attachment 1 of this report. 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 F8130721-CO001BD 1888 F8130721-CO002BD 1873 F8130721-CO003BD 1909 F8130721-C0004BD 1950 F8130721-CO005BD 1525 F8130721-C0006BD 1707 F8130721-C0007BD 1899 F8130721-CO008BD 1758 F8130721-CO009BD 1183 F8130721-CO010BD 1909 F8130721-CO011BD 1655 F8130721-C0O012BD 2220 F8130721-CO013BD 1784 F8130721-CO014BD 2236 F8130721-CO015BD 4466 F8130721-CO016BD 1919 F8130721-C0017BD 1987 F8130721-CO018BD 1618 F8130721-CO019BD 1878 F8130721-C0O02OBD 1888 F8130721-CO021BD 1644 F8130721-CO022BD 1945 F8130721-CO023BD 1592 F8130721 -CO024BD 1644 F8130721-CO025BD 2158 F8130721-CO026BD 1893 F8130721-CO027BD 1805 F8130721-CO028BD 1650 F8130721-CO029BD 2023 F8130721 -CO03OBD 2433 Page 4 of 9 FSS Summary Report F8130721 F8130721-COO3IBD 3009 F8130721-C0031BD F8130721-CO032BD Mean: Median: Standard Deviation:
S Range: 3009.2033 1971 1891 551 1183-4466 Page 5 of 9 FSS Summary Report F8130721 Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)F8130721CO001SM F8130721 C0002SM F8130721 C0003SM F8130721 C0004SM F8130721 C0005SM F8130721 C0006SM F8130721 C0007SM F8130721CO008SM F8130721CO009SM F8130721Co010SM F8130721Co011SM F8130721CO012SM F8130721CO013SM F8130721CO014SM F8130721CO015SM F8130721CO016SM F8130721C0017SM F8130721CO018SM F8130721CO019SM F8130721CO020SM F8130721C0021SM F8130721 C0022SM F8130721 C0023SM F8130721 C0024SM F8130721 C0025SM F8130721 C0026SM F8130721 C0027SM F8130721 C0028SM F8130721 C0029SM F8130721CO030SM F8130721 C0031 SM F8130721 C0032SM Mean: Median: Standard Deviation:
Ranae: 0.34 27.46 4.22-3.53 1.64-0.95-0.95 4.22 0.34 4.22 1.64 6.8-2.24 17.13 243.14 0.34-0.95 0.34 8.09 19.72 6.8 54.59 9.38 19.72 11.97 44.25-3.53 0.34 9.38 8.09 14.55 234.1 23.15 5.51 58.03-3.53 to 243.14 Page 6 of 9 FSS Summary Report F8130721 I Survey Unit Data Assessment:
The survey design required 32 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 7 of 9 FSS Summary Report F8130721 Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/I00 cm 2): N/A Ambient Background Used (dpm/100 cm 2): N/A Average Ambient BKG = 0 Actual Direct Measurements (N): 32 Median (dpm/100 cm 2): 1891 Mean (dpm!/O0 cm 2): 1971 Direct Measurement Standard Deviation 551 (dpm/100 cm 2): Total Standard Deviation (dpm/100 cm 2): 551 Based on samples and backgrounds.
Maximum (dpm/100 cm 2): 4466 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 32 S+ Value: 32 Critical Value: 21 Sufficient Samples Collected:
Yes Maximum Value < DCGL: Yes Median Value < DCGL: Yes Mean Value < DCGL: Yes Maximum Value < DCGLemc: Yes Class 1 Total Standard Deviation
<= Sigma: Yes Pass the Sign Test? Yes Reject the Null Hypothesis?
Yes Does the Survey Unit Pass All Criteria?
Yes Page 8 of 9 FSS Summary Report F8130721 Survey Unit Investigations and Results: One investigation (scan grid CO13MBS) was required for the scan measurements and the results are reported in Attachment
- 3. Investigation of the area resulted in the decision to perform additional remediation.
The investigation results in Attachment 3 represent the residual radioactivity levels achieved after additional remediation.
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 the characterization data used for survey design. One potential area of elevated activity was detected and evaluated as shown in Attachment
- 3. Therefore, the EMC criterion was met.Conclusion:
The FSS of this survey unit was properly designed as a Class 1 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 cm 2 and none of the removable surface activity measurements exceeded 10% of the DCGL.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 F8130721 meets the release criteria of 1OCFR20.1402.
.Page 9 of 9 FSS Summary Report F8130721 Attachment 1 Maps July 3, 2008 Survey Unit F8130721 CD 0 00 Cj)H.H1 M 11 CD 0 00 00 0j.ELEV -2'-0" ELEV 5" 2-Meter Line 7 Key Plan Match Line See F8130711-M1 Sheet2 ELEV -2'-0" 1, 88 189 190 ELEV-16-9" 2-Meter Line NOM ELEV 0" 19 195 I 202 193 196 201 192 197 I9 1gs 199 East Soo Wedt NorlhColmma (210 '2oMetars 21 218 209 1212 217 (208 213 216 207 214 215 East South le' 2-Meatm ELEV 5" 2-Meter Line p2Wt North Wall Scale Feet Scale Meters 0 1 2 3 SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT AUXILIARY BUILDING EL. -20'ROOM 51 SECTION 2 UPPER WALL.BETA SCAN MEASUREMENT LOCATIONS F8130721-MI OWG: 813000.02c SHEET 2 OF 3 T(CHILL C HILL CD 0Looding East West Face North East Face Face Overhead Key Plan Bottom 00 I'00 Scale Feet 8" 1 Scale Meters 0 1 9 3 SSMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT AUXILIARY BUILDING EL. -20' ROOM 51 SECTION 2 0/H STRUCTURE BETA SCAN MEASUREMENT LOCATIONS F8130721-Mi DWG: 81:3000.02c SHEET 3 OF 3 TCHLL I CE (A 0 Si~cn~r1 00'-A 0 b-i'-A.. .. ..' .' .. ...11 1 1 1 H i i i i i i i ii H H i i .... H H ! i! ,It Il Ta Mai Linee e71M Y- "LV:0'.' .. ..1 0. .:: : : : T:, : : , T .......... ....... ..: ," ':" H H I .... .... .. .... r. ... .. .... ... ..... ... .: : .... .. ... .T II571 XEs..:: : : : : ........I ".. ..... .......,,E:o]rt G o'l S outh El m T i~w elm"---1. --7 .-r:, : .... .............................
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-- ----- $i 50 (ý--) N(l DO°_Ceiling 00 0_j Scale Feet" r= 1'-0" Scale Meters 0 1 2 3*SMUI SACRAMENTO MUNICIPAL UTILITY DISTRICT AUXILIARY BUILDING EL. -20' ROOM 51 SECTION 2 CEILING BETA DIRECT/LOOSE SURFACE MEASUREMENT LOCATIONS F8130721-M2 nW(: 813000.02c SHEET 2 OF 4 TC HILL 0t 00 w ELEV -2'-0" ELEV 5" 2-Meter Line Match Line See F8130711-M2/
Sheet 3 ELEV 0" Match Line See F813071 1-M2 Sheet 3 ELEV 5" 2-Meter Line Scale Feet 81"e= M,-cr'Scale Meters Key Plan ELEV -2'-0" Match Line See F813071 1-M2 Sheet 3 ELEV 5" 2-Meter Line ELEV -2'-0" ELEV 5" 2WMeter Line'East' 'Southl South courm> 2-Mete.a S SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT AUXILIARY BUILDING EL. -20' ROOM 51 SECTION 2 UPPER BETA DIRECT/LOOSE SURFACE MEASUREMENT LOCATIONS F8130721-M2 R1 flf'~mlflA9, SHEET 3OF 4 T 0 1 2 3 ,C HILL I I .-:813000 02c SHEET 3 OF4 TCH CD 00 0 South Face LooNng Nordi West Nofh East Face Face Face Overhead sbucture collm.Key Plan cn Top E Edge Cable Chase 2.4 mm Loolag West Looftg SouIh 00 tw Scale Feet 61" = 1'-0" 8 Scale Meters 0 1 9 :3 SSMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT AUXILIARY BUILDING EL. -20' ROOM 51 SECTION 2 UPPER BETA DIRECT/LOOSE SURFACE RANDOM START LOCATION F8130721-M2Rt ngn$;HFFT 4 01:4 TC RHIL[)VVC- 8130M 02c SHEET 4 OF 4 TCH 0 9 3 0 H-3 (?0 .:,T fJ~ob, c Section I 0FE:l3 I R E2LI/- m Kj~N)S)C E-S gig 1 1 I Match Line See F8130731-M3 1C,2 Sheet 1 nll--'li L 7 , 1.+.': ': _-- ------ ......<_.. .._.__!l_'
J...5------i m Match Line See F8130701-M3 Sheet 1 Ceiling:ti~Iir 00 tW Scale Feet 32"= 1,-" Scale Meters 0 1 2 3 45 S SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT AUXILIARY BUILDING EL. -20' ROOM 51 SECTION 2 CEILING JUNCTURE BETA SCAN MEASUREMENT LOCATIONS F8130721-M3 j~t. 813nOO O.2c SHEET 1 OF 3 -THII I DWG: 81300 02c SE I O- TCIL 0 9.7 I ELEV -2!-0" 171+ýýJ29 -a,==Key Plan ELEV -16'2-Meter L-9.ine hEast Wall Match Line See 1F8130711-M3 Sheet 2 ELEV -2!-0" ELEV -1.6'-9" 2-Meter Line ELEV -2'-O0 ELEV -16'-g" 2-Meter Line ELEV -2'-".J37, ELEV 9" 2-Meter Line> 2-Metmr S2-Mastcks K North Wall No:ýNest r1t 00 w Scale Feet Scale Meters 0 1 2 3 SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT AUXILIARY BUILDING EL. -20' ROOM 51 SECTION 2 UPPER JUNCTURE BETA SCAN MEASUREMENT LOCATIONS F8130721-M3
.81300n0n2, SHEET 2OF 3 T(CHILL C HILL (8 0 J46 West North East Face Face Face Overhead Structur colmn J~ 45 Loo"dn Nwl Key Plan South Face I-.cn J50 (No Juncture atthiloCon, No measurment taken)N52 Bottomn Looking South Reflected Undoesie 00 Scale Feet 81" 8" = 1M-0s scale Meters (A 1 S SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT nwc AUXILIARY BUILDING EL. -20' ROOM 51 SECTION 2 UPPER JUNCTURE BETA SCAN MEASUREMENT LOCATIONS F8130721-M3
- '81300.02c
~oHI- I I I SHE 30F3 TCH I I'd 0 I-.Etev. 35 Room 209 Elev. -2' Room 51 O0l 00 w-.S SMUD SACRAMENTO MUNICIPAL UTILITY DISTIRICT AUXILIARY BUILDING EL. -20' ROOM 51 SECTION 2 UPPER GAMMA SCAN MEASUREMENT LOCATIONS F8130721-M4 DWG: 813000.02c SHEET 1 OF 1 TCHLL Attachment 2 Instrumentation July 3, 2008 Survey Unit F8130721 Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No. Model; Serial No. (dpmll00 cm 2) (dpm/100 cm 2)M2350; 193700 43-68B; 190294 433 1033 M2350; 149789 43-68B; 161397 433 1033 M2350; 193700 43-68B; 160691 433 1033 M2350; 149789 43-116-1B; 256006 491 f3Juncture 739 Juncture M2350; 193700 43-116-1B; 216072 491 f3Juncture 739 f3Juncture Tennelec; 0401171 N/A 5.9 dpm a, N/A 11.7 dpm N/397 Cs-137 InSpector 1000 03069793 N/A 432 Co-60 Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2)Investigation Criteria -Direct 154800 Investigation Criteria -Scan 154800 DCGLW 43000 DCGLEMc 154800 Page 2 of 2 Att. 2 Instrumentation F8130721 Attachment 3 Investigation July 3, 2008 Survey Unit F8130721 Table 3-1 Survey Unit Investigation The grid above was initially greater than survey unit design investigation level. Investigation of grid C0131BS resulted in the decision to perform additional remediation.
The investigation results above represent the residual radioactivity level after additional remediation.
Page 2 of 2 Att. 3 Investigation F8130721 Attachment 4 Data Assessment July 3, 2008 Survey Unit F8130721 F81 30721 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpmll 00cm 2 5,000 4,500 4,000 2,5001 3,7000 '~200 0 20 40 60 80 100~Percentile'
> Direct Measurements (dp-m/10cm2) -median -- --75th Percentile 50th Percentile 20--.4189 CD 50
('D0(tD 00 U.j C)F8130721 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmll00cm*
E E"k0 5000 4500 4000 3500 3000 2500 2000 1500 1000 500 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 3602 1971 317 UUUUUU UUUUU UUUUUUQUUUUU U Measurement Locations 0 o Gross Activity -Average --"+3StDev" --"-3StDev (D F8130721 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm 2 CD2 VJ)00 w 0i 1 1 1 1 1 1 1 1 7 6 5 4 3 2 1 0 9 8 7-6 5 4 3 2 1 0 0- 0 0~ N- N-I I,,-M Bins -Upper End Value (dpm/100cm2)