ML081580574
| ML081580574 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/07/2008 |
| From: | Ellen Brown Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-032 | |
| Download: ML081580574 (18) | |
Text
Rancho Seco Final Status Survey Summary Report April 7, 2008 Barrel Farm Soil Survey Unit F8430011 Prepared By: */Lk2
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Date: tf/7/26*d8 FS.iner Reviewed By:
Date: 1,/2O Approved By:
Da Date:
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F843001 1, Barrel Far m Soil Survey Unit
Description:
Operating History: ThI area was used for the temporary storage of packaged radioactive material as well as the' segregation and consolidation of waste packages. Operating records and the HSA document several leaks/spills with the potential for a release of radioactivity associated with this survey area. The HSA documented the storage of radioactive material within the area that may have had the potential to contaminate the area.
Site Characterization: Soil samples were collected and analyzed for the presence of plant-derived radionuclides.2 Cs-137 was the primary nuclide of plant origin detected with a mean activity level of 0.750 pCi/g and a maximum value of 4.250 pCi/g. Based on the classification procedure (DSIP-0020) and low levels of Cs-137 reported, the area was determined to be a Class 1 land 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 p
2 locations were determined using a random-start, fixed grid pattern and 1313 mi were scanned for approximately 100% coverage. Soil samples were collected at each direct measurement location land 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 F8430011
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area:
F843 Barrel Farm Soil Survey Unit:
0011 Open Land Area Class:
1 LTP Table 5-4 SU Area (m2):
1313 Evaluator:.
Erin L. Brown DCGL Cs137 surrogate (pCi/g):
51.2 Area Factor:
1.2 Class 1 Design DCGLemc (pCi/g):
64 Class 1 Conservatively based on (area factor)(51.2)
LBGR (pCi/g):
25.6 Adjusted Design Sigma (pCi/g):
1.46 DTBD-06-001, Table 5-4D Type I Error:
0.05 Type II Error:
0.05 Nuclide:
Cs137 Sample Area (m2):
93.8 Class 1 Total Area Scanned (m2):
1313 Scan Coverage (%):
100%
Class 1 Zl.*, :
1.645 Z*_IP :
1.645 Sign P:
0.99865 Calculated Relative Shift:
17.5 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:
9.7 Class 1 Page 3 of 7 FSS Summary Report F8430011
Survey Results:
A total of 16 direct measurements were made in F84300 11. 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. 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 Cs137 MDA Cs137 Activity Uncertainty Mean: N *
! ****?!6.34E-02.............,
Median:
5.71E-02 I
Standard Deviation:_________
- 2. 12E-02 Range:
5.05E-02 to 1.39E-01 F8430011SOOO1SS 5.05E-02
< 5.05E-02 F8430011S0002SS 5.09E-02
< 5.09E-02 F8430011S0003SS 5.44E-02
< 5.44E-02 F8430011S0004SS 5.75E-02
< 5.75E-02 F8430011S0005SS 5.19E-02
< 5.19E-02 F8430011S0006SS 5.31E-02
< 5.31E-02 F8430011S0007SS 5.59E-02
< 5.59E-02 F8430011S0008SS 6.20E-02
< 6.20E-02 F8430011S0009SS 6.40E-02
< 6.40E-02 F8430011SOO1OSS 7.63E-02 1.39E-01 5.33E-02 F8430011SO011SS 6.71E-02
< 6.71E-02 F8430011S0012SS 5.41E-02
< 5.41E-02 F8430011S0013SS 6.41E-02
< 6.41E-02 F8430011S0014SS 5.93E-02
< 5.93E-02 F8430011S0015SS 7.31E-02
< 7.31E-02 F8430011S0016SS 5.66E-02
< 5.66E-02 Page 4 of 7 FSS Summary Report F8430011
Survey Unit Data Assessment:
The survey design required 16 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 Page 5 of 7 FSS Summary ReportF8011 F84300.11
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N):
16 Median (pCi/g):
5.71E-02 Mean (pCi/g):
6.34E-02 Standard Deviation (pCi/g):
2.12E-02 Maximum (pCi/g):
1.39E-01 Sign Test Final N Value:
16 S+ Value:
16 Critical Value:
11 Sufficient Samples Collected:
Yes Maximum Value < DCGL:
Yes Median Value < DCGL:
Yes Mean Value < DCGL:
Yes Maximum Value < DCGLemc:
Yes Class 1 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 F8430011
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 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 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. All of the direct measurements were less than the DCGL. No investigationswere 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 F843001 1 meets the release criteria of 10CFR20.1402.
Page 7 of 7 FSS Summary Report F8430011 Maps April 7, 2008 Survey Unit F8430011
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BARREL FARM SOIL GAMMA SCAN MEASURENE NTLOCATIONS 8430011 -M3 Instrumentation April 7, 2008 Survey Unit F8430011
Table 2-1. Survey Unit Instrumentation Detector Detector Serial M
Instrument Model No.
N.No..MD No.'
HPGe N/A 05069128 Soil - 0.07 pCi/g Cs-137 Soil - 0.3 pCi/g Cs-137 ISOCS N/A 2983947 Soil - 0.2 pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value Soil-20 pCi/g Cs-13 7 ISOCS Investigation Criteria - Scan Soil - 5.7 pCi/g Co-60 51.2 Cs-137 All DCGLW 12.6 Co-60 All DCGLEMC 64pCi/g Page 2 of 2 Att. 2 Instrumentation F8430011 Investigation April 7, 2008 Survey Unit F8430011 (none required)
Data Assessment April 7, 2008 Survey Unit F8430011
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F8430011 Quantile Plot Cs137 DCGL = 51.2 pCilg 0.160 - -
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