ML081610158
| ML081610158 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/05/2008 |
| From: | Tallman D Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| F8000141 | |
| Download: ML081610158 (24) | |
Text
Rancho Seco Final Status Survey Summary Report April 5, 2008 Northern Industrial Area (land)
Survey Unit F8000141 Prepared By:!Dan A. Tallman ate: April 5, 2008 FSS EfIeed Reviewed By: _
Date: #,i,/D Lead 4 SS Engineer Approved By:
Date:
Dismnantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8000141, Northern Industrial Area (land)
Survey Unit
Description:
Operating History:
Survey F8000141 - Northern IA Land Areas, provided for the survey and evaluation of the non-paved lands areas located primarily north of the site's two cooling towers..As shown in, these areas extending from the eastern Industrial Area security fence adjacent to the staff parking lots west to encompass the western Spray Pond and its associate dirt berm.
These land areas were characterized individually as four distinct units during the characterization phase of the RSSI as follows:
800013 - Central Industrial Area, Class 3 - 14,676 square meters This area was located north of, and extending to the south-east of, the cooling towers to the PAP, exclusive of the PAP, sewer plant, water treatment building, chlorine building, and intake structure. This area was used for the storage and/or transport of radioactive material. Operating records and the HSA document several nearby leaks or 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.
800014 - North Industrial Area Boundary, Class 3 - 6,410 square meters This area was located to the north of the spray ponds extending to the IA fence. This area was used for the storage of radioactive material. Operating records and the HSA document several nearby leaks or 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.
803002 - Quonset-Hut Yard Class 3 - 13,075 square meters This area was located to the northeast of the cooling towers and east of the spray ponds, excluding the Quonset hut pad itself. This area was used for the storage of radioactive material.
Operating records and the HSA document several events 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.
806003 - East/West Spray Ponds, Class 3 - 21,600 square meters This area was located to the north of the cooling towers and surrounding the spray ponds. This area was used for the storage of radioactive material. Operating records and the HSA document several events 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.
Page 2 of 9 FSS Summary Report F8000141
Characterization data collected within these areas, summarized below, revealed no elevated levels of contamination and confirmed the essentially uniform nature of these units.
SUID Name Sigma Mean pCi/g, Cs-137 Maximum pCi/g, Cs-137 800013 Central Industrial Area 0.030 0.070 0.149 800014 North Industrial Area 0.007 0.060 0.068 Boundary 803002 Quonset-Hut Yard 0.030 0.077 0.146 806000 East/West Spray Ponds 0.026 0.069 0.167 (Site background levels of Cs-137 have been determined to be approximately 0.312 pCi/g.)
Based on this uniformity and the contiguous nature of the areas, F8000141 consolidated all four into a single Class 3 Survey Unit designated 8000141, the boundaries of which were located by SMUD survey crews and are shown on survey map F8000141-Ml As described in section 2 of the LTP, the area was evaluated using DSIP-0020 and was designated as Class 3.
Page 3 of 9 FSS Summary Report F8000141
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 5460 m2 were scanned for approximately 10%
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.
C Page 4 of 9 FSS Summary Report F8000141
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area:
F800 Northern Industrial Area (land)
Survey Unit:
0141 Open Land Area Class:
3 LTP Table 5-4 SU Area (m 2);
55761 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 Default = 50% DCGL Design Sigma (pCi/g):
0.03 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):
5460 Scan Coverage (%):
9.8%
Class 3 Zl-a :
1.645 Zlp :
1.645 Sign P:
0.99865 Calculated Relative Shift:
853.3 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 5 of 9 FSS Summary Report F8000141
Survey Results:
A total of 14 direct measurements were made in F8000141. 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:
7.8 1 E-02 Median:
6.76E-02.
Standard Deviation: <,i 3.89E-02 Range:
4.13E-02 to 2.0 1E-01 F8000141SOOO1SS 7.1OE-02
< 7.1OE-02 F8000141SO002SS 6.78E-02
< 6.78E-02 F8000141SO003SS 5.73E-02
< 5.73E-02 F8000141SO004SS 4.66E-02
< 4.66E-02 F8000141SO005SS 4.13E-02
< 4.13E-02 F8000141SO006SS 6.35E-02
< 6.35E-02 F8000141SO007SS 6.37E-02
< 6.37E-02 F8000141SO008SS 5.51E-02
< 5.51E-02 F8000141SO009SS 6.11E-02 2.01E-01 5.45E-02 F8000141SOO1OSS 8.55E-02
< 8.55E-02 F8000141SO011SS 9.36E-02
< 9.36E-02 F8000141SO012SS 8.66E-02
< 8.66E-02 F8000141SO013SS 6.75E-02
< 6.75E-02 F8000141S0014SS 9.31E-02
< 9.31E-02 Page 6 of 9 FSS Summary Report F8000141
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 greater than the design standard deviation. Use of Standard Deviation vs. design sigma does not alter the relative shift used to determine the minimum number of direct measurements, so no additional samples were required.
Page 7 of 9 FSS Summary Report F8000141
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N):
14.
Median (pClg):
6.76E-02 Mean (pCi/g):
7.8 1E-02 Standard Deviation (pci/g):
3.89E-02 Maximum (pCi/g):
2.01E-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:
Investigate Use of Standard Deviation vs. design sigma does not alter the relative shift used to determine the minimum number of direct measurements required.
Pass the Sign Test?
Yes Reject the Null Hypothesis?
Yes The survey unit passes all conditions?
Yes I Page 8 of 9 FSS Summary Report F8000141
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 3 land survey and the sample results are consistent with that classification. The variability of the survey results was greater 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 F8000141 meets the release criteria of I OCFR20.1402.
Page 9 of 9 FSS Summary Report F8000141 Maps April 5, 2008 Survey Unit F8000141
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"**-*" SACRAMENTOJ MUNiCIPAL U I'ILI'I'Y 0DI5TRICTf NORTHERN INDUSTRIAL AREA LAND GAMMA SCAN LOCATIONS FSOOO1 41 -M7 Instrumentation April 5, 2008 Survey Unit F8000141
Table 2-1. Survey Unit Instrumentation Detector Instrument Model Detector Serial MDC No.
No.
Soil - 0.0866 pCi/g Cs-137 Soil - 0.0561 pCi/g Co-60 Soil - 0.0936 pCi/g Cs-137 Soil - 0.0728 pCi/g Co-60 Soil - 0.630 pCi/g Cs-137 ISOCS N/A 1983920 Soil - 0.319 pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value ISOCS Investigation Criteria - Scan Soil - 23 pCi/g Cs-137surr HPGe Investigation Criteria-Direct 25.8 pCi/g All DCGLw 51.6 Cs-137 12.6 Co-60 Page 2 of 2 Att. 2 Instrumentation F8000141 Investigation April 5, 2008 Survey Unit F8000141 (none required)
Data Assessment April 5, 2008 Survey Unit F8000141
F8000141 Quantile Plot Cs137 DCGL = 51.6 pCi/g 0J 00 0.250 0.2001-o0.1so 0 0.100 0.050 0.000 0.068 100 0
20 40 60 80 Percentile
+
Activity
-Median
- 75th Percentile --
- - 50th Percentile]
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F8000141 Scatter Plot C9137 DCGL = 51.6 pClIg C>
C/3 Cn 00 CD C:>
2.60E-01 2.00E-01
!1.50E-01 Y1.OOE-01 S5.00E-02
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C) 00 F8000141 Frequency Plot Csl 37 DCGL = 51.6 pCi/g LL C-0 aI) 0 13 12 11 10 9
8 7
6 5
4 3
2 1
0 Pýý N
N (V
Bins - Upper End Value (pCi/g)