ML081580573
| ML081580573 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/25/2008 |
| From: | Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-032 | |
| Download: ML081580573 (21) | |
Text
Rancho Seco Final Status Survey Summary Report March 25, 2008 Transformer Yard Survey Unit F8390001 Prepared By:
Date: March 25, 2008 Date:
6/26 K Reviewed Lead FSF.n eer Approved By:
f7j/7 Date:_______
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8390001, Transformer Yard Survey Unit
Description:
Operating History: The area surrounded the main station transformer pads. The adjacent area was used for the storage of radioactive material. 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 adjacent 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. Cs-137 was the primary nuclide of plant origin detected with a mean activity level of 0.266 pCi/g and a maximum value of 0.913 pCi/g. Based on the classification procedure (DSIP-0020) and initial levels of Cs-137 reported, the area was determined to be a Class 3 land area.
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 392 m2 were scanned for approximately 12%
coverage. Soil samples were collected at each of the ten direct measurement locations falling on the dirt/gravel surfaces associated with the survey unit and analyzed by HPGe detector. Direct Gamma Measurements, using the Inspector 1000 (with a characterized 2" by 2" NaI detector), were taken at each of the four direct measurement locations falling on the asphalt surfaces associated with the survey unit. 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 F8390001
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area:
F839 Transformer Yard Survey Unit:
0001 Open Land Area Class:
3 LTP Table 5-4 SU Area (m2):
3385 Evaluator:
D.A.Tallman 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 50% DCGLW Design Sigma (pCi/g):
0.432 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):
392 Scan Coverage (%):
11.6%
Class 3 1.645 ZI-P:
1.645 Sign P:
0.99865 Calculated Relative Shift:
59.2 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 F8390001
Survey Results:
A total of 14 direct measurements were made in F8390001. 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: ~
-01 Median:
5.80E-02 Standard Deviation:
IK,3.62E-01 Range:
3.83E-02 to 8.75E-01 F8390001A0002GD 8.75E-01
< 8.75E-01 F8390001A0004GD 8.49E-01
< 8.49E-01 F8390001A0001GD 7.69E-01
< 7.69E-01 F8390001A0003GD 8.36E- 01
< 8.36E-01 F8390001S0012SS 4.20E-02 4.23E-02 2.89E-02 F8390001SO013SS 4.30E-02 1.85E-01 4.29E-02 F8390001S0014SS 5.61E-02
< 5.61E-02 F8390001S0018SS 5.90E-02
< 5.90E-02 F8390001S0001SS 6.86E-02 7.36E-02 4.54E-02 F8390001SO002SS 4.37E-02
< 4.37E-02 F8390001SO004SS 4.78E-02
< 4.78E-02 F8390001S0007SS 3.83E-02
< 3.83E-02 F8390001S0009SS 5.23E-02
< 5.23E-02 F8390001SOO1OSS 4.11E-02 5.70E-02 2.94E-02 Page 4 of 7 FSS Summary Report F8390001
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 F8390001
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N):
14 Median (pci/g):
5.80E-02 Mean (pCi/g):
2.85E-01 Standard Deviation (pCi/g):
3.62E-01 Maximum (pCi/g):
8.75E-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 F8390001
Survey Unit Investigations and Results:
No investigations were required for eitheir 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 F8390001 meets the release criteria of IOCFR20.1402.
Page 7 of 7 FSS Summary Report F8390001 Maps May 1, 2008 Survey Unit F8390001
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'I SACRAMEHITO MUNICIPAL UTILITY DISTRICT TRANSFORMER YARD SURVEY MAP ISOCS SCAN LOCATIONS F8390001 -M3 0 1 SHT 2 OF 2 DWG: 839000 Instrumentation March 25, 2008 Survey Unit F8390001
Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model Nor MDC No.
No.
HPGe N/A 05069128 Soil - 0.3 pCi/g Cs-137 Asphalt -
0.84 pCi/g Co-=60 Inspector N/A 08051294 Asphalt- 0.88 pCi/g Cs-137 ISOCS N/A 2983947 Soil - 0.34 pCi/g Cs-137 Soil - 0.23 pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value Inspector/
Investigation Criteria -
Soil - 25.6 pCi/g Cs-137 HPGe Direct measurement/Soil Sample Soil - 6.3 pCi/g Co-60 50% DCGLw Asphalt - 25.6 pCi/g Cs-137 Soil - 20 pCi/g Cs-137 ISOCS Investigation Criteria-Scan Soil - 5 pCi/g Co-60 Asphalt - 20 pCi/g Cs-137 All.
DCGLW 52.6 Cs-137
.12.6 Co-60 Page 2 of 2 Att. 2 Instrumentation F8390001 Investigation March 25, 2008 Survey Unit F8390001 (none required)
Page I of I Att. 3 Investigation Data Assessment March 25, 2008 Survey Unit F8390001
CD 00 C:)
Cd) 13 F8390001 Quantile Plot Cs137 DCGL = 52.6 pCilg U
U 1.000 0.900 0.800 0.700 0.600 0.500 0.400 0.300 0.200 0.100 0.000 0.058 0
20 40 60 Percentile 80 100 I
Activity -
Median -
- - 75th Percentile - -.
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C/2 00 F8390001 Scatter Plot Cs137 DCGL =52.8 pCilg 1.S5E+00 1.OOE+00 00 S5.OOE-O1
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