ML090900731
| ML090900731 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 02/04/2009 |
| From: | Frank G Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097 | |
| Download: ML090900731 (18) | |
Text
Rancho Seco Final Status Survey Summary Report February 4, 2009 Switch Yard South/Retention Basin Buffer Survey Unit F8510005 Prepared By:&f1 QC Date:___________
FSS Engineer Reviewed By Date: 7- / Ilq Lead FSS Engineer Approved By: Date: 2r Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8510005, Switch Yard South/Retention Basin Buffer 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.
Page 2 of 8 FSS Summary Report F8510005
Survey Area Classification 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 1100 m2 were scanned for approximately 14%
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 3 of 8 FSS Summary Report F8510005
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area: F851 Switch Yard South/Retention Basin Buffer Survey Unit: 0005 Open Land Area Class: 3 LTP Table 5-4 SU Area 2 (jn' ): 7913 Evaluator: Gary Frank DCGL Cs137 surrogate (pci/g): 51.2 Area Factor: 0 Class 3 Design DCGLemc (pCi/g): N/A Class 3 LBGR (pCi/g): 25.6 Default = 50% DCGL Design Sigma (pCi/g): 0.047 DTBD-06-001, Table 5-4B Retention Basin Buffer Type I Error: 0.05 Type II Error: 0.05 Nuclide: Cs137 Sample Area (m2): N/A Class 3 Total Area Scanned (m2): 1100 Scan Coverage (%): 13.9% Class 3 1.645 1.645 Sign P: 0.99865 Calculated Relative Shift: 544.6 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 4 of 8 FSS Summary Report F8510005
Survey Results:
A total of 14 direct measurements were made in F8510005. The results including mean, median, standard deviation and range are shown in Table 2. All of the direct (soil) measurements were less than the DCGL. None of the scan measurements indicated areas of elevated activity above MDC with the MDC for Cs-137 at 0.399 pCi/g and Co-60 at 0.236 pCi/g. Soil samples 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: ~ ; ~ t 7.48E-02 Median: 6.50E-02 Standard Deviation: 2.39E-02 Range: 5.64E-02 to 1.44E-01 F8510005S0001SS 6.89E-02 < 6.89E-02 F8510005S0002SS 6.35E-02 < 6.35E-02 F8510005S0003SS 6.83E-02 < 6.83E-02 F8510005S0004SS 7.78E-02 < 7.78E-02 F8510005S0005SS 6.03E-02 .< 6.03E-02 F8510005S0006SS 9.54E-02 < 9.54E-02 F8510005S0007SS 6.36E-02 9.99E-02 4.57E-02 F8510005SO008SS 6.26E702 < 6.26E-02 F8510005S0009SS 5.64E-02 < 5.64E-02 F8510005SOO1OSS 6.60E-02 < 6.60E-02 F8510005SO011SS 6.00E-02 < 6.00E-02 F8510005S0012SS 6.60E-02 1.44E-01 5.45E-02 F8510005S0013SS 6.01E-02 < 6.01E-02 F8510005S0014SS 6.39E-02 < 6.39E-02 Page 5 of 8 FSS Summary Report F8510005
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 miedian values were less than the DCGL. The sample standard deviation was less than the design standard deviation so no additional samples were required.
Page 6 of 8 FSS Summary Report F8510005
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N): 14 Median (pCi/g): 6.50E-02 Mean (pCi/g): 7.48E-02 Standard Deviation (pci/g): 2.39E-02 Maximum (pCi/g): 1.44E-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 7 of 8 FSS Summary Report F8510005
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 unitwas 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 asa 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 F8510005 meets the release criteria of 10CFR20.1402.
Page 8 of 8 PFSS Summary Report F8510005
Attachment 1 Maps February 4, 2009 Survey Unit F8510005
00 T14 00
CD 0
00
Attachment 2 Instrumentation February 4, 2009 Survey Unit F8510005
Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model No.MDC No.
HPGe N/A 05069128 Soil - 0.0954 pCi/g Cs-137 Soil - 0.0702 pCi/g Co-60 ISOCS N/A 2983947 Soil - I pCi/g Cs-137 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value ISOCS Investigation Criteria - Scan Soil -25.6 pCi/g Cs-137 Soil - 6.3 pCi/g Co-60 Soil - 25.6 pCi/g Cs-137 HPGe Investigation Criteria Soil - 6.3 pCi/g Co-60 51.2 Cs-137 All DCGLw 12.6 Co-60 Page 2 of 2 Att. 2 Instrumentation F8510005
Attachment 3 Investigation February 4, 2009 Survey Unit F8510005 (none required)
Attachment 4 Data Assessment February 4, 2009 Survey Unit F8510005
F8510005 Quantile Plot Cs137 DCGL = 51.2 pCi/g 0.160 -
0.140 -
0.120 -
U) 0.100 -
U 0.080 -
00 .5 C.) 0.065 0.060 -
0.040 -
0.020 -
0.000 -I-0 20 40 60 80 100 Percentile I + Activity - Median - - - 75th Percentile -. - - - 50th Percentile I
CD w F8510005 Scatter Plot 2.Cs137 DCGL = 51.2 pClIg 1.60E-01 1.40E-.01 - - -, - --------- .46 1.20E-01
.O0E-01 -
oo>O 00E
.6400E-02 o 0 0 0 0 O
40
>4.00E-02 CD 2.00E-02 0.00E+00 Ia"-. . .... ... aa .. a a a" 0Measurement Locations 0D I Activity - Average
"+3StDev ...
"-3StDev" C )......0.....
CrQ F8510005 Frequency Plot Csl 37 DCGL = 51.2 pCi/g 13-12-11 -
10-a) 9-8-
.2 7-6-
a) 5-0 4-3-
2-1-
0-N N
<Il 00 Bins - Upper End Value (pC i/g)