ML081580575
| ML081580575 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/06/2008 |
| From: | Ellen Brown Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-032 | |
| Download: ML081580575 (18) | |
Text
C~t2LA I Rancho Seco Final Status Survey Summary Report April 6, 2008 Barrel Farm Berm (soil)
Survey Unit F8430021 Prepared By: z ~z§ c~iQ Date: 41612009 Reviewed By: Date: I/74f L
-Lea--ýSs Engineer Approved By: Date: -
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8430021, Barrel Farm Berm (soil)
Survey Unit
Description:
Operating History: This area was the berm that surrounded the paved area that was used for the temporary storage of packaged radioactive material as well as the segregation and consolidation of waste packages.
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 1668 m2 were scanned for approximately 33% 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 PFSS Summary Report F8430021
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Srvurvey Area: F843 Barrel Farm Berm (soil)
Survey Unit: 0021 Open Land Area Class: 2 LTP Table 5-4 SU Area (m2): 5000 Evaluator: Erin L. Brown DCGL Cs137 surrogate (pCi/g): 51.2 Area Factor: N/A Class 2 Design DCGLemc (pCi/g): N/A Class 2 LBGR (pCi/g): 25.6 Adjusted Design Sigma (pci/g): 0.034 DTBD-06-001, Table 5-4D Type I Error: 0.05 Type II Error: 0.05 Nuclide: Cs137 Sample Area (n2): 357.1 Class 2 Total Area Scanned (m2): 1668 Scan Coverage (%): 33.4% Class 2 ZIa : 1.645 ZI-0 ý 1.645 Sign P: 0.99865 Calculated Relative Shift: 752.9 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: 18.9 Class 2 Page 3 of 7 FSS Summary Report F8430021
Survey Results:
A total of 15 direct measurements were made in F8430021. 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 a~ctivity. Soil samples were counted to the MDC shown in Table 2-1 of .
Table 2. Direct Measurement Results (all activity values in pCi/g)
Measurement ID Mean:
Median:
Standard Deviation:
Cs137 MDA Cs137 Activity 5.7 1E-02 5.68E-02 Ij Uncertainty
__________ 7.67E-03 Range: 4.62E-02 to 7.72E-02 F8430021S0001SS 5.21E-02 < 5.21E-02 F8430021SO002SS 5.68E-02 < 5.68E-02 F8430021S0003SS 5.73E-02 < 5.73E-02 F8430021S0004SS 5.63E-02 < 5.63E-02 F8430021S0005SS 4.88E-02 < 4.88E-02 F8430021SO006SS 6.07E-02 < 6.07E-02 F8430021S0007SS 5.44E-02 < 5.44E-02 F8430021S0008SS 6.12E-02 < 6.12E-02 F8430021S0009SS 6.27E-02 < 6.27E-02 F8430021S0010SS 5.79E-02 < 5.79E-02 F8430021S0011SS 5.50E-02 < 5.50E-02 F8430021S0012SS 4.62E-02 < 4.62E-02 F8430021S0013SS 4,71E-02 < 4.71E-02 F8430021S0014SS 7.72E-02 < 7.72E-02 F8430021S0015SS 6.28E-02 < 6.28E-02 Page 4 of 7 FSS Summary Report F8430021
Survey Unit Data Assessment:
The survey design required 15 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 F8430021
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N): 15 Median (pci/g): 5.68E-02 Mean (pCi/g): 5.71E-02 Standard Deviation (pCi/g): 7.67E-03 Maximum (pCi/g): 7.72E-02 Sign Test Final N Value: 15 S+ Value: 15 Critical Value: 11 Sufficient Samples Collected: Yes Maximum Value < DCGL: Yes Median Value < DCGL: Yes Mean Value < DCGL: Yes Maximum Value < DCGLemc: N/A Class 2 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 F8430021
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 2 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 2 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 F8430021 meets the release criteria of 10CFR20.1402.
Page 7 of 7 FSS Summary Report F8430021
Attachment 1 Maps April 6, 2008 Survey Unit F8430021
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Attachment 2 Instrumentation April 6, 2008 Survey Unit F8430021
Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model No.MDC No.N HPGe N/A 05047773 Soil - 0.06 pCi/g Cs- 137 HPGe N/A 05069128 Soil - 0.06 pCi/g Cs-137 Soil - 0.2 pCi/g Cs-137 ISOCS N/A 2983947 Soil - 0.3 pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value Soil - 20 pCi/g Cs-137 ISOCS Investigation Criteria - Scan Soil - 5.7 pCi/g Co-60 All DCGLw 51.2 Cs-137 12.6 Co-60 All DCGLEMC N/A Page 2 of 2 Aft. 2 Instrumentation F8430021-
Attachment 3 Investigation April 6, 2008 Survey Unit F8430021 (none required)
Attachment 4 Data Assessment April 6, 2008 Survey Unit F8430021
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F8430021 Quantile Plot Cs137 DCGL = 51.2 pCi/g 0.090 0.080 0.070 0.060 U 0.057
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F8430021 Scatter Plot Csl37 DCGL = 51.2 pCItg 0"
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O F8430021 Frequency Plot Cs1 37 DCGL = 51.2 pCi/g
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