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-*
Date:
il 7 20 Lead FSS Engineer Approved By:
Date:
,7 0
- 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 cm2 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:
Survey Unit:
Class:
SU Area (m2):
Evaluator:
DCGL (dpm/100 cm2):
Area Factor:
Design DCGLemc (dpm/100 cm2):
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 (%):
Zia0 Sign P:
Calculated Relative Shift:
Relative Shift Used:
N-Value:
Design N-Value + 20%:
Design Min Samples N:
Grid Spacing L:
F813 0741 1
288 Michael Stein 43000 3.6 154800 21500 12035 0.05 0.05 Cs-137 6.9 288 100%
1.645 1.645 0.955435 1.7 1.7 14 17 42 2.6 West Heat Removal CoOler Room West of Column N, Room 052 Ceiling and Upper Walls Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class 1 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 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 cm2 for Co-60 and 3,910 to 10,300 dpm/100 cm2 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 FBI 30741 -COO32BD 1758 F81 30741 -CO033BD 11 F8I130741 -CO034BD91 F81 30741 -CO035BD 10 FBI130741 -CO036BD 19 FBI130741 -CO037BD 13 FBI130741 -CO038BD 19 FBI130741 -CO039BD 14 FBI130741 -CO04OBD 10 FBI130741 -C0041 BD 18 FBI130741 -CO042BD 10 FBI130741 -CO043BD 19 Standard Deviation:23 1758
- 1613, 991 1707 15b8 1437 1095 1141 1307 1489 1509 1499
,1559 1551 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 F8130741 C0002SM F8130741 C0003SM F8130741 C0004SM F8130741COOO5SM F8130741 C0006SM F8130741 C0007SM F8130741CO008SM F8130741CO009SM F8130741CO010SM F8130741CO011SM F8130741CO012SM F8130741CO013SM F8130741C0014SM F8130741CO015SM F8130741CO016SM F8130741 C001 7SM F8130741CO018SM F8130741CO019SM F8130741 C0020SM F8130741 C0021 SM F8130741 C0022SM F8130741 C0023SM F8130741 C0024SM F8130741 C0025SM F8130741 C0026SM F8130741 C0027SM F8130741 C0028SM F8130741 C0029SM F8130741 C0030SM F8130741C0031SM F8130741C0032SM F8130741CO033SM F8130741C0034SM F8130741 C0035SM F8130741 C0036SM F8130741CO037SM F8130741 C0038SM F8130741 C0039SM F8130741CO040SM F8130741 C0041 SM F8130741 C0042SM F8130741 C0043SM Mean:
Median:
Standard Deviation:
Range:
4.22 10.68
-0.95
-4.82 0.34 0.34
-2.24 8.09 4.22 5.51
-2.24
-3.53
-0.95 6.8 5.51
-3.53 2.93 2.93
-3.53
-0.95 1.64
-2.24
-0.95 1.64
-3.53 4.22 35.21 6.8 1.64
-3.53
-0.95
-0.95 1.64
-4.82
-2.24
-3.53
-4.82
-2.24
-6.11
-2.24
-2.24 0.34 4.22 1.07
-0.95 6.63
-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 cm2):
N/A Average Ambient BKG 0
Actual Direct Measurements (N):
43 Median (dpm/100 cm2):
1551 Mean (dpm/1 cm2) 1559 Direct Measurement Standard Deviation 230 (dpm/100 cm 2)
Total Standard Deviation (dpm/100 cm2):
230 Based on samples and backgrounds.
Maximum (dpm/100 cm2):
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 Maps June 25, 2008 Survey Unit F8130741
00 0T ESTIMATED AREA Ceiling 96.4 m 2
Walls 110.3 m2 Column 8.5 m2 Mezzanine.- 72.5 m2 Scale Feet
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Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No.
Model; Serial No.
(dpmll00 cm 2 )
(dpm/100 cm2)
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 InSpector 1000 10054579 N/A 11900 Co-60 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 ue CM )
(dpm/100 c2 Investigation Criteria - Direct 154800 Investigation Criteria - Scan 154800 DCGLw 43000 DCGLEMC 154800 Page 2 of 2 Att. 2 Instrumentation F81301741 Investigation June 25, 2008 Survey Unit F8130741 (none required)
Data Assessment June 25, 2008 Survey Unit F8130741
CF8130741 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm2 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 2248 E 2000-0 0 00 00 000 0
0o 0
0 0
0 -
.1500 -or 0
0 "10 E
0 0
0 U
oo
>**1000
.o0
~
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1 00000000000000 0**0 Measurement Locations
-0 Gross Activi Average-a
"+3StDev a- -
"3StDev" O~~
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i I
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Cl) 00 Lk F8130741 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm2 11 C
10 9
8-7-
6 5
4 3
2 1
Cgj Bins - Upper End Value (dpm/1l O0cm2)