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 By:*o-I 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: F813 East Heat Removal Cooler Room Between Columns 9.2 and 9.7, Room 051 Upper Walls and Ceiling Survey Unit: 0721 Structure Surface Class: 1 LTP Table 5-4 SU Area (m2): 220 Evaluator: Michael Stein DCGL (dpm/100 cm 2 ): 43000 Gross Activity DCGL Area Factor: 3.6 Class 1 Design DCGLemc 154800 Class I (dpm/100 cm 2 ):
LBGR (dpm/100 cm 2): 21500 Default = 50% DCGL Design Sigma (dpm/100 2 cm ): 12035 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): 6.9 Class 1 Scan Area (M ):2 220 Scan Coverage (%): 100% Class I 1.645 1.645 Sign P: 0.955435 Calculated Relative Shift: 1.7 Relative Shift Used: 1.7 Uses 3.0 if Relative Shift is
>3 N-Value: 14 Design N-Value + 20%: 17 NUREG-1575 Table 5-5 Design Min Samples N: 32 Class I Grid Spacing L: 2.6 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
3009 F8130721-COO3IBD F8130721-C0031BD 3009 F8130721-CO032BD .2033 Mean: 1971 Median: 1891 Standard Deviation:
551 S Range: 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 0.34 F8130721 C0002SM 27.46 F8130721 C0003SM 4.22 F8130721 C0004SM -3.53 F8130721 C0005SM 1.64 F8130721 C0006SM -0.95 F8130721 C0007SM -0.95 F8130721CO008SM 4.22 F8130721CO009SM 0.34 F8130721Co010SM 4.22 F8130721Co011SM 1.64 F8130721CO012SM 6.8 F8130721CO013SM -2.24 F8130721CO014SM 17.13 F8130721CO015SM 243.14 F8130721CO016SM 0.34 F8130721C0017SM -0.95 F8130721CO018SM 0.34 F8130721CO019SM 8.09 F8130721CO020SM 19.72 F8130721C0021SM 6.8 F8130721 C0022SM 54.59 F8130721 C0023SM 9.38 F8130721 C0024SM 19.72 F8130721 C0025SM 11.97 F8130721 C0026SM 44.25 F8130721 C0027SM -3.53 F8130721 C0028SM 0.34 F8130721 C0029SM 9.38 F8130721CO030SM 8.09 F8130721 C0031 SM 14.55 F8130721 C0032SM 234.1 Mean: 23.15 Median: 5.51 Standard Deviation: 58.03 Ranae: -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 cm2 ): 1891 Mean (dpm!/O0 cm2): 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 10CFR20.1402.
. Page 9 of 9 FSS Summary Report F8130721
Attachment 1 Maps July 3, 2008 Survey Unit F8130721
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Key Plan 00 ELEV 5" I 19 195 202 2-Meter Line ELEV -2'-0" Match Line See F8130711-M1 Sheet2 1,88 193 196 201 189 192 197 190 I91gs 199 ELEV-16-9" 2-Meter Line NOM East Soo Wedt NorlhColmma (210 '2oMetars 21 218 ELEV 0" 209 1212 217 (208 213 216 207 214 215 ELEV 5" North Wall 2-Meter Line p2Wt East South le 00 ' 2-Meatm Scale Feet 0j AUXILIARY BUILDING EL. -20' ROOM 51 SECTION 2 UPPER WALL Scale Meters SMUD .BETA SCAN MEASUREMENT LOCATIONS SACRAMENTO MUNICIPAL 0 1 2 3 UTILITY DISTRICT F8130721-MI OWG:813000.02c SHEET 2 OF 3 T( CHILL C HILL
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SECTION 2 UPPER GAMMA SCAN MEASUREMENT LOCATIONS SACRAMENTO MUNICIPAL UTILITY DISTIRICT 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 cm2 ) (dpm/100 cm2 )
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 00cm2 5,000 4,500 .#-*.
- 4,000 2,5001 3,7000 '~
200
--.4189 CD 50 0 20 40 60 80 100
~Percentile'
> Direct Measurements (dp-m/10cm2) -median-- - - 75th Percentile 50th Percentile 20
('D L*)
0 F8130721 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmll00cm*
5000 4500 0 E 4000 3500 3602 3000 0 E 0 2500 "k0 0 0 0 2000 1971 0 0 0 0 0 0 0 0 00 r~J*
1500 0 (tD 0
1000 500 317 0
U.j UUUUUU UUUUU UUUUUUQUUUUU U Measurement Locations 00 C) o 0 Gross Activity - Average - - "+3StDev" - - "-3StDev
(D F8130721 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm 2 17 16 15 14 13 12 11 0i 10 9
8 CD2 7
-6 VJ) 5 4
3 2
1 0
0-0 I,,-M 0~ N- N-I 00 w Bins - Upper End Value (dpm/100cm2)