ML090900729
| ML090900729 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 01/06/2009 |
| From: | Tallman D Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097 | |
| Download: ML090900729 (18) | |
Text
Rancho Seco Final Status Survey Summary Report January 6, 2009 Tank Farm N.E. Quadrant - Subsurface soil Survey Unit F8100032 Prepared By: Dan A. Tallman L K Date: January 6, 2009 FSS Engin er Reviewed By: c4 ,j Date: -- o9 Lead FSS Engineer Approved By: Date:
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8100032, Tank Farm N.E. Quadrant - Subsurface soil Survey Unit
Description:
Operating History: This area, traditionally referred to as the Tank Farm, surrounded the tanks used to store radioactive liquids. Subsequent to plant operations, this area was used for the storage of radioactive material and equipment, include that used to perform the demolition of the reactor building concrete structures. 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.
Site Characterization: As documented in F810003 1, surface 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 379 pCi/g and a maximum value of 1,040 pCi/g.
Based on the potential for sub-surface contamination within the unit, the decision to perform an investigation of the sub-surface soil was made. This investigation resulted in the collection of 43 soil samples, the locations of which coincided with those of the surface soil evaluation. The results of these samples and the statistical tests performed are also consistent with the evaluations performed on the surface soil component evaluated in F8100031. Based on the classification procedure (DSIP-0020) and consistent with the classification applied to the surface soil component, the area was designated a Class 1 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 spatial locations were based on the surface soil locations sampled in F8100031. Sub-Surface samples were then collected at one meter intervals. Samples taken from a depth of -15 cm (depth of surface soil samples) to -115 cm are designated as minus one meter (-
1m) samples while those taken from the interval -115cm to -215 cm are referred to as minus two meter (-2m) samples. Due to the existence of numerous sub-surface utility support structures (piping, cable duct-boxes, sewer lines, etc.) as well as over dimension fill and debris existing undetected below grade level, sample refusal was not an uncommon occurrence. One incident of refusal culminated in the inability to acquire a two meter sample within a one meter radius (the relocation allowance criteria) of the surface and one meter sample locations accounting for the existence of 22 minus one meter samples and 21 minus two meter samples. Each soil sample taken was 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 F8100032
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area: F810 Tank Farm N.E. Quadrant -
Subsurface soil Survey Unit: 0032 Open Land Area Class: 1 LTP Table 5-4 SU Area (m2): 1942 Evaluator: D.A.Tallman DCGL Cs137 surrogate (pCi/g): 51.2 Area Factor: 1.2 Class 1 Design DCGLemc (pCi/g): 61.5 Class 1 LBGR (pCi/g): 25.6 Default = 50% DCGL Design Sigma (pCi/g): 10.7 DTBD-06-001, Table 5-4D Type I Error: 0.05 Type II Error: 0.05 Nuclide: Cs137 Sample Area (m2): 100 Class 1 Total Area Scanned (m2): 1942 Scan Coverage (%): 100% Class 1 ZI.* 1.645 1.645 Sign P: 0.97725 Calculated Relative Shift: 2.3 Relative Shift Used: 2.3 Uses 3.0 if Rel Shift >3 N-Value: 12 Design N-Value + 20%: 15 NUREG-1575 Table 5-5 Grid Spacing L: 10 Class 1 modified to meet minimum "N" Page 3 of 7 P 3FSS Summary Report F8100032
Survey Results:
A total of 43 direct measurements were made in F8100032. The results including mean, median, standard deviation and range are shown in Table 2. All of the direct measurements were less than the DCGL. Soil samples were counted to the MDC shown in Table 2-1 of Attachment 2.
Page 4 of 7 FSS Summary Report F8100032
Table 2. Direct Measurement Results (all activity values in pCi/g)
Measurement ID Cs137 MDA Cs137 Activity Uncertainty Mean: 4.85E-02 Median: 4.78E-02 Standard Deviation: * ! 8.61E-03 Range: 3.29E-02 to 6.98E-02 F8100032S0011SS 6.98E-02 < 6.98E-02 F8100032S0021SS 4.43E-02 < 4.43E-02 F8100032S0031SS 5.95E-02 < 5.95E-02 F8100032S0041SS 5.04E-02 < 5.04E-02 F8100032S0051SS 5.60E-02 < 5.60E-02 F8100032S0061SS 6.36E-02 < 6.36E-02 F8100032S0071SS 4.01E-02 6.26E-02 3.16E-02 F8100032S0081SS 4.71E-02 < 4.71E-02 F8100032S009ISS 5.66E-02 <5.66E-02 F8100032SOOlSS 5.93E-02 < 5.93E-02 F8100032S0111SS 4.60E-02 < 4.60E-02 F8100032S0121SS 3.40E-02 < 3.40E-02 F8100032S0131SS 5.62E-02 < 5.62E-02 F8100032S0141SS 5.49E-02 < 5.49E-02 F8100032S0151SS 5.18E-02 < 5.18E-02 F8100032S0161SS 4.37E-02 < 4.37E-02 F8100032S0171SS 5.62E-02 < 5.62E-02 F8100032S0181SS 5.44E-02 < 5.44E-02 F8100032S0191SS 4.83E-02 < 4.83E-02 F8100032S020ISS 5.57E-02 < 5.57E-02 F8100032S0211SS 5.52E-02 < 5.52E-02 F8100032S0221SS 3.74E-02 < 3.74E-02 F8100032S0012SS 4.52E-02 < 4.52E-02 F8100032S0022SS 3.94E-02 < 3.94E-02 F8100032S0042SS 4.12E-02 < 4.12E-02 F8100032S0052SS 4.14E-02 < 4.14E-02 F8100032S0062SS 5.00E-02 < 5.OOE-02 F8100032S0072SS 4.32E-02 < 4.32E-02 F8100032S0082SS 3.87E-02 < 3.87E-02 F8100032S0092SS 4.08E-02 < 4.08E-02 F8100032S0102SS 4.34E-02 < 4.34E-02 F8100032S0112SS 3.44E-02 5< 3.44E-02 F8100032S0122SS 4.15E-02 < 4.15E-02 F8100032S0132SS 5.53E-02 < 5.53E-02 F8100032S0142SS 4.70E-02 < 4.70E-02 F8100032S0152SS 4.31E-02 < 4.31E-02 F8100032S0162SS 3.66E-02 < 3.66E-02 F8100032S0172SS 4.90E-02 < 4.90E-02 F8100032S0182SS 4.46E-02 < 4.46E-02 F8100032S0192SS 5.43E-02 < 5.43E-02 F8100032S0202SS 5.28E-02 < 5.28E-02 F8100032S0212SS 4.78E-02 < 4.78E-02 F8100032S0222SS 3.29E-02 < 3.29E-02 Page 5 of 7 FSS Summary Report F8100032
Survey Unit Data Assessment:
The survey design required 43 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.
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N): 43 Median (pCi/g): 4.78E-02 Mean (pCi/g): 4.85E-02 Standard Deviation (pCi/g): 8.61E-03 Maximum (pCi/g): 6.98E-02 Sign Test Final N Value: 43 S+ Value: 43 Critical Value: 27 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 F8100032
Survey Unit Investigations and Results:
No investigations were required, therefore, 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 as a subsurface survey, the scan coverage requirement is not applicable. 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 F8100032 meets the release criteria of 10CFR20.1402.
Page 7 of 7 FSS Summary Report F8100032
Attachment 1 Maps January 6, 2009 Survey Unit F8100032
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1963.5 rr9 TANK FARM - ZONE 3 SOIL
ýI1 Sol GENERAL ARRANGEMENT PLAN VIEW I 0API Rg33!5M SCALE METERS
~smuD SURFACE AREA ESTIMATE 0 5 10 SACRAMETO M4UNICIPAL UTILITY DISTRICT F8100031-Mi SHEET 1 OF 1
m.ROAD:
N-0
- uc 00 TANK. FARM - ZONE 3 SOIL SOIL SAMPLE k) RANDOM START LOCATION SCALE MEIERS SACRAMENTO MUNICIPAL i0:1 UTILTY F STRCT F8100031-M2
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ZONE 2 SCALEMETERS ITJ 00 0 5 10 TANK FARM - ZONE 3 BETA DIRECT MEASUREMENT LOCATIONS SACIRAMENTO MUNICIPAL
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tJTI ITY 61TR F8100031-M2 SHEET 2 OF 2
Attachment 2 Instrumentation January 6, 2009 Survey Unit F8100032
Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model No.MDC
.No.
Soil - 0.0698 pCi/g Cs-137 Soil - 0.0680 pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value HPGe Investigation Criteria 61.5 pCi/g Cs137 surr.
All DCGLw 51.2 pCi/g Cs-137 12.6 pCi/g Co-60 All DCGLEMc 61.5 pCi/g Cs 137 surr.
Page 2 of 2 Att. 2 Instrumentation F8100032
Attachment 3 Investigation January 6,92009 Survey Unit F8100032 (none required)
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Attachment 4 Data Assessment January 6, 2009 Survey Unit F8100032
F8100032 Quantile Plot Cs137 DCGL = 51.2 pCi/g 0.080 0.070 0.060 0.050 0.048 U
a.
0.040
.5 Cj2 C.)
CD, 0.030 W
0.020 0.010 0.000 0 20 40 60 80 100 Percentile I ActiAity - Median - - - 75th Percentile - -. 50th Percentile I 00
C-FBI 00032 Scatter Plot Cs137 DCGL = 51.2 pCig 8.00E-02
. . . . . . . . . . . . . . . . . . . . . . . . . . . . ..- 0.074 7.00E 6.00E-02 o 0 0 0 0 0 0 00 5.OOE-02 -_ 0 -00 o- -. 049 00 0 0 00 -
,_ 4.00E-02 0 00 00 0 0 C., 3.OOE-02 0 0 0023 2.OOE-02 I.00E4-2 0.0012+00 ~wuww wwwu nWWWWOWWWWWWWWWW*nWWWWnm mmm mwmw wowrm Measurement Locations 0 AclNvity -- Average - - "+3SIDeN" - - "-3StDev " -
00
F8100032 Frequency Plot Cs1 37 DCGL = 51.2 pCi/g 9
8 7
6 U- 5 4
-0 3 2
0 1
00 0
(b.
Bins - Upper End Value (pCi/g)
C)