ML081610154
| ML081610154 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/25/2008 |
| From: | Frank G Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| F5010042 | |
| Download: ML081610154 (17) | |
Text
Rancho Seco Final Status Survey Summary Report March 25, 2008 Extended Parking/Storage Area Survey Unit F5010042 Prepared By_______
Date:..___
FSS ngi ee Reviewed By:_
Date:
-A'Z-VB Lead PS Engineer Approved By:
2 Date:
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F5010042, Extended Parking/Storage Area Survey Unit
Description:
Operating History: The area extended from the parking lot to the plant access road in the northeast quadrant of the site. Operating records and the HSA document the potential for a release of radioactivity in this survey area. The HSA recorded two potential release events. one event involved the discovery of a pallet of articles labeled a's "Contact RP prior to disassembly outside the RCA". In addition, the area was used as a staging area for outgoing and incoming radioactive material shipments. The access road over which shipments were made runs through the area.
Site Characterization: Soil samples were collected and analyzed for the presence of plant-derived radionuclides. Cs-137 was the only detected nuclide of plant origin with a mean activity level of 0.088 pCi/g and a maximum value of 0.232 pCi/g. Based on the classification procedure (DSIP-0020), the area was determined to be a Class 3 area.
HSA Events: none 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 1272 m were scanned for approximately 3%
coverage. Soil samples were collected at each direct measurement location and analyzed by HPGe detector. 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 F5010042
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area:
F501 Survey Unit:
Class:
SU Area (m2):
Evaluator:
DCGL Cs137 surrogate (pCi/g):
Area Factor:
Design DCGLemc (pCi/g):
LBGR (pCi/g):
Design Sigma (pCi/g):
Type I Error:
Type II Error:
Nuclide:
Sample Area (m2):
Total Area Scanned (Mn2):
Scan Coverage (%):
Zl-,, :
Sign P:
Calculated Relative Shift:
Relative Shift Used:
N-Value:
Design N-Value + 20%:
Grid Spacing L:
0042 3
38692 Gary Frank 51.2 N/A N/A 25.6 0.058 0.05 0.05 Cs137 N/A 1272 3.3%
1.645 1.645 4
441.3 3
11 14 N/A Extended Parking/Storage Area Open Land Area LTP Table 5-4 Class 3 Class 3 Default = 50% DCGL DTBD-06-001, Table 5-4D Class 3 Class 3 Uses 3.0 if Rel Shift >3 NUREG-1575 Table 5-5 Class 3 Page 3 of 7 FSS Summary Report F5010042
Survey Results:
A total of 14 direct measurements were made in F5010042. 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. Gamma Directs were counted to the MDC shown in Table 2-1 of.
Table 2. Direct Measurement Results (all activity values in pCi/g)
Measurement ID Cs137 MDA Cs137 Activity Uncertainty Mean.
6.77E-01I Median:~
6.80E-01
~>
Standard Deviation:
3.78E-02 1
Range:
6.29E-01 to 7.36E-01 F5010042AOOO1GD 6.48E-01
< 6.48E-01 F5010042A0002GD 6.36E-01
< 6.36E-01 F5010042A0003GD 7.24E-01
< 7.24E-01 F5010042A0004GD 6.67E-01
< 6.67E-01 F5010042A0005GD 7.02E-01
< 7.02E-01 F5010042A0006GD 7.20E-01
< 7.20E-01 F5010042A0007GD 7.09E-01
< 7.09E-0I F5010042A0008GD 6.45E-01
< 6.45E-01 F5010042A0009GD 6.95E-01
< 6.95E-01 F5010042A0010GD 6.29E-01
< 6.29E-01 F5010042AOO 11GD 6.43E-01
< 6.43E-01 F5010042A0012GD 6.35E-01
< 6.35E-01 F5010042A0013GD 6.92E-01
< 6.92E-01 F5010042A0014GD 7.36E-01
< 7.36E-01 Page 4 of 7 FSS Summary Report F5010042
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 F5010042
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N):
14 Median (pCi/g):
6.80E-01 Mean (pci/g):
6.77E-01 Standard Deviation (pCi/g):
3.78E-02 Maximum (pCi/g):
7.36E-01 Sign Test Final N Value:
14 S+ Value:
14 Critical Value:
9 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 Survey Unit Passes Page 6 of 7 FSS Summary Report F5010042
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, 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 F5010042 meets the release criteria of 10CFR20.1402.
Page 7 of 7 FSS Summary Report F5010042 Maps March 25, 2008 Survey Unit F5010042
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- lC RAYAJOIII7 Instrumentation March 25, 2008 Survey Unit F5010042
Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model No.MDC No.
Inspector N/A 08051294 Asphalt - 0.441 pCi/g Cs-137 ISOCS N/A 2983947 Asphalt - 0.736 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 Inspector DInvestigation Criteria-Asphalt - 26.3 pCi/g Cs-137 A51.2 Cs-137 All DCGLw 12.6 Co-60 All DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F5010042 Investigation March 25, 2008 Survey Unit F5010042 (none required)
Data Assessment March 25, 2008 Survey Unit F5010042
clQ 0
F5010042 Quantile Plot Cs137 DCGL = 51.2 pCi/g U
.5 U
0.760 0.740 0.720 I 0.700 0.680 -
0.660 -
0.640 0.620 -
0 0.68 20 40 60 Percentile 80 100 Activity -
Median -
- -75th Percentile -
50th Percentile]
(t~
C U) 0 F5010042 Scatter Plot Cst37 DCGL = 51.2 pCilg 9.00E 8.00E-Oi
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791 7.00E-01 o
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Actiity Average
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F5010042 Frequency Plot Cs1 37 DCGL = 51.2 pCi/g 0
8 7
6 5
4 3
2 1
0 Bins - Upper End Value (pCi/g)