ML082620168
| ML082620168 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 06/25/2008 |
| From: | Stein M Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| F8130741, MPC&D 08-064 | |
| Download: ML082620168 (32) | |
Text
Rancho Seco Final Status Survey Summary Report June 25, 2008 West Heat Removal Cooler Room West of Column N, Room 052 Ceiling and Upper Walls (Including the Floor, Walls, and Ceiling of the Mezzanine)
Survey Unit F8130741 Prepared By: .Date: 462 FSS Engineer Reviewed By:,*: W ý-* *
- Dismantlement uperintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8130741, West Heat Removal Cooler Room West of Column N, Room 052 Ceiling and Upper Walls (Including the Floor, Walls, and Ceiling of the Mezzanine)
Survey Unit
Description:
Operating History: The West 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/100 cm 2 and a maximum value of 10,080,000 dpm/l00 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 West Heat Removal Cooler Room there were a number of areas on the walls, ceiling, and floor of the Mezzanine 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 ceiling and upper walls of the West Heat Removal Cooler Room West of Column N, which included the floor, walls, and ceiling of the Mezzanine.
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 288 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 9 FSS Summary Report F8130741
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F813 West Heat Removal CoOler Room West of Column N, Room 052 Ceiling and Upper Walls Survey Unit: 0741 Structure Surface Class: 1 LTP Table 5-4 SU Area (m2): 288 Evaluator: Michael Stein DCGL (dpm/100 cm 2): 43000 Gross Activity DCGL Area Factor: 3.6 Class 1 Design DCGLemc 154800 Class 1 (dpm/100 cm 2):
LBGR (dpm/100 cm 2): 21500 Default = 50% DCGL Design Sigma (dpm/100 cm ):2 12035 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): 6.9 Class 1 Scan Area (M2): 288 Scan Coverage (%): 100% Class 1 1.645 Zia0 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: 42 Class 1 Grid Spacing L: 2.6 Class 1 Page 3 of 9 FSS Summary Report F8130741
Survey Results:
A total of 43 direct measurements were made in F8130741. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. None of the beta scan measurements indicated areas of elevated activity. Scan activity ranged from 1,790 to 14,657 dpm/100 cm2 , based on a surveyor efficiency of 0.5 and no background subtracted. None of the gamma scan measurements indicated areas of elevated activity. Scan activity ranged from 5,053 to 24,807 dpm!100 cm 2 Cs-137. The MDCs for the gamma scan measurements were 4,790 to 11,900 dpm/100 cm 2 for Co-60 and 3,910 to 10,300 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 F8130741-C0001BD 1535 F8130741-CO002BD 1426 F8130741-CO003BD 1478 F8130741-CO004BD 1390 F8130741-COOO5BD 1426 F8130741-CO006BD 1193 F8130741-CO007BD 2246 F8130741-CO008BD 1779 F8130741-CO009BD 1816 F8130741-COOIOBD 1904 F8130741-CO011BD 1416 F8130741-CO012BD 1323 F8130741-CO013BD 1675 F8130741-CO014BD 1556 F8130741-CO015BD 1541 F8130741-CO016BD 1582 F8130741-CO017BD 1784 F8130741-CO018BD 1681 F8130741-CO019BD 1748 F8130741-CO02OBD 1665 F8130741-C0021BD 1784 F8130741-C0022BD 1655 F8130741-C0023BD 1867 F8130741-CO024BD 1494 F8130741-CO025BD 1520 F8130741-CO026BD 1395 F8130741-CO027BD 1608 F8130741-CO028BD 1463 F8130741-CO029BD 1551 F8130741-CO03OBD 1634 F8130741-CO031BD 1738 Page 4 of 9 FSS Summary Report F8130741
Y 1758 FBI 30741 -COO32BD 1758 F81 30741 -CO033BD 1613, 11 F8I130741 -CO034BD91 991 F81 30741 -CO035BD 1707 10 15b8 FBI130741 -CO036BD 19 FBI130741 -CO037BD 1437 13 FBI130741 -CO038BD 1095 19 FBI130741 -CO039BD 1141 14 FBI130741 -CO04OBD 1307 10 FBI130741 -C0041 BD 1489 18 FBI130741 -CO042BD 1509 10 FBI130741 -CO043BD 1499 19
,1559 1551 Standard Deviation:23 230 991-2246 Range: 991 - 2246 Page 5 of 9 FSS Summary Report F8130741
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)
F8130741COOOISM 4.22 F8130741 C0002SM 10.68 F8130741 C0003SM -0.95 F8130741 C0004SM -4.82 F8130741COOO5SM 0.34 F8130741 C0006SM 0.34 F8130741 C0007SM -2.24 F8130741CO008SM 8.09 F8130741CO009SM 4.22 F8130741CO010SM 5.51 F8130741CO011SM -2.24 F8130741CO012SM -3.53 F8130741CO013SM -0.95 F8130741C0014SM 6.8 F8130741CO015SM 5.51 F8130741CO016SM -3.53 F8130741 C001 7SM 2.93 F8130741CO018SM 2.93 F8130741CO019SM -3.53 F8130741 C0020SM -0.95 F8130741 C0021 SM 1.64 F8130741 C0022SM -2.24 F8130741 C0023SM -0.95 F8130741 C0024SM 1.64 F8130741 C0025SM -3.53 F8130741 C0026SM 4.22 F8130741 C0027SM 35.21 F8130741 C0028SM 6.8 F8130741 C0029SM 1.64 F8130741 C0030SM -3.53 F8130741C0031SM -0.95 F8130741C0032SM -0.95 F8130741CO033SM 1.64 F8130741C0034SM -4.82 F8130741 C0035SM -2.24 F8130741 C0036SM -3.53 F8130741CO037SM -4.82 F8130741 C0038SM -2.24 F8130741 C0039SM -6.11 F8130741CO040SM -2.24 F8130741 C0041 SM -2.24 F8130741 C0042SM 0.34 F8130741 C0043SM 4.22 Mean: 1.07 Median: -0.95 Standard Deviation: 6.63 Range: -6.11 to 35.21 Page 6 of 9 FSS Summary Report F8130741
Survey Unit Data Assessment:
The survey design required 42 direct measurements for the Sign Test. In actuality, 43.
direct measurements were obtained. 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 F8130741
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm 2): N/A Ambient Background Used (dpm/100 cm 2): N/A Average Ambient BKG 0 Actual Direct Measurements (N): 43 Median (dpm/100 cm 2): 1551 Mean (dpm/1 cm 2) 1559 Direct Measurement Standard Deviation 230 2
(dpm/100 cm )
Total Standard Deviation (dpm/100 cm 2): 230 Based on samples and backgrounds.
Maximum (dpm/100 cm 2): 2246 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 43 S+ Value: 43 Critical Value: 27 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 F8130141
Survey Unit Investigations and Results:
No investigations were required for either direct or scan measurements and no investigation results are reported.
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. No potential areas of elevated activity were detected.
==
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. No investigations were required.
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 F8130741 meets the release criteria of 10CFR20.1402.
Page 9 of 9 FSS Summary Report F8130741
Attachment 1 Maps June 25, 2008 Survey Unit F8130741
00 ESTIMATED AREA Scale Feet Ceiling 96.4 m 2 +"= i'-o" 2 AUXILIARY BUILDING EL. -20' 0T Walls 110.3 m Column 8.5 m 2 Scale Meters ROOM 52 WEST OF COL. "N", CEILING 2
Mezzanine .- 72.5 m BETA-SCAN MEASUREMENT LOCATIONS TOTAL 287.7 m2 0 1 2 3 F81 30741-Mi
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0 AUXILIARY BUILDING EL. -20' ROOM 52 w Scale Meters WEST OF COLUMN "N", UPPER WALLS BETA SCAN -MEASUREMENT LOCATIONS SACRAMENTO MUNICIPAL 0 1 2 3 UTILITY DISTRICT F81'30741-Mi
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0 ON KEYPLANS Scale Feet 00 AUX. BLDG. EL. -20' ROOM 52 UPPER WEST OF COL. "N" BETA DIRECT/LOOSE o I..
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0 S216m 2.c KEYPLANS Scale Feet 00 *" = 1-0" AUXILIARY BUILDING EL. -20'- ROOM 52 MEZZANINE - BETA DIRECT/LOOSE Scale Meters ,SMUD SURFACE MEASUREMENT-LOCATIONS-
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0 0j Scale Feet 00
-1,-o" AUX. BLDG. EL. -20' - ROOM 52 CEILING WEST OF COLUMN N - BETA DIRECT/LOOSE Scale Meters
- SURFACE MEASUREMENT LOCATIONS 0
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\/N 00 t0c wi Reflected Ceiling AUXILIARY BUILDING EL. -20'- ROOM 52 L.I WEST OF COLUMN "N" - UPPER JUNCTURE BETA SCAN LOCATIONS---
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KEYPLANS Scale Feet 00 AUXILIARY BUILDING EL. -20' ROOM 52 w
SSMUD WEST OF COLUMN "N", UPPER WALLS Scale Meters GAMMA SCAN MEASUREMENT LOCATIONS SACRAMENTO MUNICIPAL 0 1 2 3 UTILITY DISTRICT F8130741-M4 T( I
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Attachment 2 Instrumentation June 25, 2008 Survey Unit F8130741
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan 2
Model; Serial No. Model; Serial No. (dpmll00 cm ) (dpm/100 cm 2 )
M2350; 180733 43-98B; 148638 820 1490 M2350; 180733 43-94; 148620 2630 4580 M2350; 203486 43-68B; 190476 433 1033 M2350; 203486 43-68B; 161400 433 1033 M2350; 142509 43-68B; 160699 433 1033 M2350; 149789 43-116-1B; 256006 796 3258 M2350; 203486 43-116-1B; 190173 796 3258 M2350; 180733 43-111B; 148641 1230 2230 5.9 dpm a,N/
Tennelec; 0401171 N/A 11.7 dpmfa N/A 10300 Cs-137 10054579 N/A 11900 Co-60 InSpector 1000 11900 Co-60 The scan and static MDC's provided represent the most conservative MDC values for the survey conducted.
Table 2-2. Investigation Criteria and DCGL Value Parameter Val uec2 (dpm/100 CM )
Investigation Criteria - Direct 154800 Investigation Criteria - Scan 154800 DCGLw 43000 DCGLEMC 154800 Page 2 of 2 Att. 2 Instrumentation F81301741
Attachment 3 Investigation June 25, 2008 Survey Unit F8130741 (none required)
Attachment 4 Data Assessment June 25, 2008 Survey Unit F8130741
CF8130741 Gross Activity Sample Results Quantile Plot 2
DCGL = 43000 dpm/1 00cm 2,500 2,000 I+
1,000 500 ;
0 20 40 60 80 100 IPercentile
-*
- Direct Measurements (dpm/100cm2) median - - - 75th Percentile - 50th Percentile
0*
0 F8130741 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmll00cmn 2500 .
E2000- - -- - 2248 0 - 0 00 00 000 0 0o 0 0 0 0-
.1500 -or 0 0 - - "10 E 0 0 0 U oo
>**1000 .o0 ~
S500 1 - 00000000000000 0**0 0 J I I I O~~ . ~ lI II l0IINII I .... i I .. I I Measurement Locations
-0 Gross Activi - Average- a "+3StDev a- - "3StDev"
0 F8130741 Gross Activity Frequency Plot 2
DCGL = 43000 dpm/1 00cm 11 10 9
8-7-
6 C
5 CD)
Cl) 4 3
2 1
Cgj 00 Bins - Upper End Value (dpm/1l O0cm2)
Lk