ML081580590
| ML081580590 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 05/01/2008 |
| From: | Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| F8510002 | |
| Download: ML081580590 (17) | |
Text
Rancho Seco Final Status Survey Summary Report April 2, 2008 Switch Gear (Wire Yard) Paved Areas Survey Unit F8510002 Prepared By __
Date:
_-_____R Date:
Reviewed LeaddF(SS En ineer Approved By:
7 Date:
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8510002, Switch Gear (Wire Yard) Paved Areas Survey Unit
Description:
Operating History: The area consisted of both paved and soil covered land. The area was located. on the west side of the IA and contained the electrical switchgear for the system grid. Operating records and the HSA document the storage of radioactive material within the area.
Site Characterization: Soil samples were collected and showed Cs-137 at'mean activity levels of 0.056pCi/g and a maximum activity of 0.072 pCi/g. Based on the classification procedure (DSIP-0020) and levels of activity reported, the area was determined to be a Class 3 area.
HSA Events: HSA Report pg. 64.
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 randomly determined and 424 m2 were scanned for approximately 3%
coverage. Gamma measurements were made at each direct measurement location and analyzed by the Inspector 1000. 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 7 FSS Summary Report F8510002
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area:
F851 Switch Gear (Wire Yard)
Paved Areas Survey Unit:
0002 Open Land Area Class:
3 LTP Table 5-4 SU Area (m2):
14505 Evaluator:
Gary Frank DCGL Cs137 surrogate (pCi/g):
51.2 Area Factor:
N/A Class 3 Design DCGLemc (pCi/g):
N/A Class 3 LBGR (pCi/g):
25.6 Default = 50% DCGL Design Sigma (pCi/g):
0.097 DTBD-06-001, Table 5-4D Type I Error:
0.05 Type II Error:
0.05 Nuclide:
Cs137 Sample Area (m2):
N/A Class 3 Total Area Scanned (m2):
424 Scan Coverage (%):
2.9%
Class 3 ZI_, :
1.645 ZIp :
1.645 Sign P:
0.99865 Calculated Relative Shift:
263.9 Relative Shift Used:
3 Uses 3.0 if Rel Shift >3 N-Value:
11 Design N-Value + 20%:
14 NUREG-1575 Table 5-5 Grid Spacing L:
N/A Class 3 Page 3 of 7, FSS Summary Report F8510002
Survey Results:
A total of 14 direct measurements were made in F8510002. The results including mean, median, standard deviation and range are shown in Table 2. All of the direct measurements were less than the DCGL. None of the scan measurements indicated areas of elevated activity. Direct measurements were counted to the MDC shown in Table 2-1 of Attachment 2.
Table 2. Direct Measurement Results (all activity values in pCi/g)
Measurement ID Cs137 MDA Cs137 Activity Uncertainty Mean:
8.20E-01I Median:
~
8.19E-0 I Standard Deviation:
2.81 E-02 Range:
7.70E-01 to 8.77E-01 F8510002 AOOO1GD 8.32E-01
< 8.32E-01 F8510002 A0002GD 8.01E-01
< 8.01E-01 F8510002 A0003GD 8.1OE-01
< 8.10E-01 F8510002 A0004GD 8.14E-01
< 8.14E-01 F8510002 A0005GD 8.51E-01
< 8.51E-01 F8510002 A0006GD 8.04E-01
< 8.04E-01 F8510002 A0007GD 8.24E-01
< 8.24E-01 F8510002 A0008GD 8.27E-01
< 8.27E-01 F8510002 A0009GD 8.77E-01
< 8.77E-01 F8510002 AOO1OGD 8.OOE-01
< 8.OOE-01 F8510002 AOO11GD 7.87E-01
< 7.87E-01 F8510002 A0012GD 8.27E-01
< 8.27E-01 F8510002 A0013GD 8.52E-01
< 8.52E-01 F8510002A0014GD 7.70E-01
< 7.70E-01 Page 4 of 7 FSS Summary Report F8510002
Survey Unit Data Assessment:
The survey design required 14 direct measurements for the Sign Test. The critical value and the results of the Sign Test are presented in Table 3. 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 5 of 7 FSS Summary Report F8510002
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N):
14 Median (pCi/g):
8.19E-01 Mean (pCi/g):
8.20E-01 Standard Deviation (pCi/g):
2.81E-02 Maximum (pCi/g):
8.77E-01 Sign Test Final N Value:
14 S+ Value:
14 Critical Value:
10 Sufficient Samples Collected:
Yes Maximum Value < DCGL:
Yes Median Value < DCGL:
Yes Mean Value < DCGL:
Yes Maximum Value < DCGLemc:
N/A Class 3 Standard Deviation <= Sigma:
Yes Pass the Sign Test?
Yes Reject the Null Hypothesis?
Yes The survey unit passes all conditions?
Yes Page 6 Of 7 FSS Summary Report F8510002
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 3 land 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 3 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. All of the direct measurements were less than 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 F8510002 meets the release criteria of 10CFR20.1402.
Page 7 of 7 FSS Summary Report F8510002 Maps April 2, 2008 Survey Unit F8510002
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SACRAMENTO MUNICIPAL UTILITY DISTRICT RLE: 85100 WIRE YARD GAMMA ISOCS SCANS F851 000-M4 RC RAYMOND Instrumentation April 2, 2008 Survey Unit F8510002
Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model No.
MDC No.
Inspector N/A 08051294 Asphalt - 0.877 pCi/g Cs-137 ISOCS N/A 1983920 Asphalt- 0.382 pCi/g Cs-137 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value ISOCS Investigation Criteria - Scan Asphalt - 26.3 pCi/g Cs-137 All DCGLW 51.2 Cs-137 Al______Gw_12.6 Co-60' All DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8510002 Investigation April 2, 2008 Survey Unit F8510002 (none required)
Data Assessment April 2, 2008 Survey Unit F8510002
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F8510002 Quantile Plot Cs137 DCGL = 51.2 pCi/g 0.900 0.880 0.860 0.840 0.820 0,800 0.780 0.760 0.819 0
20 40 60 80 100 Percentile Activity -
Median -
- 75th Percentile -
- 50th Percentile
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F8510002 Scatter Plot Cs137 DCGL = 51.2 pClIg 1.00E+00 9.00E-0.1
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Average "
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F8510002 Frequency Plot Cs1 37 DCGL = 51.2 pCi/g 0
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N Bins - Upper End Value (pCi/g)