ML081580599
| ML081580599 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 05/12/2008 |
| From: | Donna Anderson Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| F8991073 | |
| Download: ML081580599 (18) | |
Text
Rancho Seco Final Status Survey Summary Report March 19, 2008 Clean Drain System - Turbine Building Drains and Oily Water Separator Survey Unit F8991073 Prepared By:
2b*.
- /r.*uA2o Date:
Z/I1q/2008' FSS Engineer Reviewed By:__
Date:__-_,_i__*,_
Lead/FSS Engineer Approved By:
v/
Date:
Dismantlemen -Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8991073, Clean Drain System - Turbine Building Drains and Oily Water Separator, Transformer Yard trench to remove drain piping Survey Unit
Description:
Operating History: This system provided a pathway to route various Turbine Building drains through the storm water drain pipe into the oily water separator. Operating records and the HSA document occurrences of radioactive contamination associated with this system piping.
Site Characterization: Direct measurements were made of the interior surfaces of the system piping. Direct measurements of the interior showed a mean gross activity level of 368 dpm/100 cm 2 and a maximum value of 634 dpm/100 cm 2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the system was determined to be a Class 3 system.
The Transformer Yard drain line, which drained to Manhole 17 and subsequently to the Oily Water Separator, was excavated and removed in September 2006. A 4-ft. portion of the drain line pipe was allowed to remain in place due to the installation of a concrete electrical duct bank around the line.
HSA Events: HSA Report pg. 63.
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 determined based on an approximate size of 5 m2 and 55 m2 were scanned for 100% 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 2 of 7 FSS Summary Report F8991073
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area:
F899 Clean Drain System -
Turbine Building Drains
/
and Oily Water Separator Survey Unit:
1073 Open Land Area Class:
3 LTP Table 5-4 SU Area (m):
55 Evaluator:
D. Anderson DCGL Cs137 surrogate (pCi/g):
51.2 Area Factor:
N/A Class 3 Design DCGLemc (pCi/g):
N/A Class 3 LBGR (pCi/g):
50.93 Adjusted Design Sigma (pCi/g):
0.09 DTBD-06-001, Table 5-4E Type I Error:
0.05 Type II Error:
0.05 Nuclide:
Cs137 Sample Area (m2):
N/A Class 3 Total Area Scanned (m2):
55 Scan Coverage (%):
100%
Class 3 ZI_, :
1.645 ZI-P :
1.645 Sign P:
0.99865 Calculated Relative Shift:
3.1 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 F8991073
Survey Results:
A total of 15 direct measurements were made in F89991073. 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.
All drain line piping was removed from the Transformer Yard area, with the exception of 4 feet of 6-inch pipe embedded in a concrete duct bank. Direct measurements were performed with an M2350 and 44-157 pipe detector. One minute scaler counts were taken every 15 cm along the 4-ft. pipe segment for a 100% survey. The mean gross activity level of the piping was 2,724 dpmr/100 cm 2 with a maximum value of 2,926 dpm/100 cm 2. The instrumentation used for the survey along with the MDC value is listed in Table 2-1 in Attachment 2.
Table 2. Direct Measurement Results (all activity values in pli/g)
Measurement ID Cs137 MDA Cs137 Activity Uncertainty Mean:
4.91 E-02 Median:
4.97E-02 Standard Deviation:
6.24E-03 Range:
4.OOE-02 to 6.37E-02 F8991073S0001SS 4.84E-02
< 4.84E-02 F8991073S0002SS 5.41E -02
< 5.41E-02 F8991073S0003SS 5.07E-02
< 5.07E-02 F8991073S0004SS 5.22E-02
< 5.22E-02 F8991073S0005SS 4.95E-02
< 4.95E-02 F8991073S0006SS 6.37E-02
< 6.37E-02 F8991073S0007SS 4.01E-02
< 4.01E-02 F8991073S0008SS 4.58E-02
< 4.58E-02 F8991073S0009SS 5.09E-02
< 5.09E-02 F8991073S0010SS 4.21E-02
< 4.21E-02 F8991073S0011SS 4.35E-02
< 4.35E-02 F8991073S0012SS 5.48E-02
< 5.48E-02 F8991073S0013SS 5.12E-02:
< 5.12E-02 F8991073S0014SS 4.OOE-02
< 4.OOE-02 F8991073S0015SS 4.97E-02
< 4.97E-02 Page 4 of 7 FSS Summary Report F8991073
Survey Unit Data Assessment:
The survey design required 15 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 F8991073
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N):
15 Median (pCi/g):
4.97E-02 Mean (pCi/g):
4.9 1E-02 Standard Deviation (pCi/g):
6.24E-03 Maximum (pCi/g):
6.37E-02 Sign Test Final N Value:
15 S+ Value:
15 Critical Value:
11 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 F8991073
.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), 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 F8991073 meets the release criteria of 10CFR20.1402.
Page 7 of 7 FSS Summary Report F8991073 Maps March 19, 2008 Survey Unit F8991073
Map F8991073-1, Clean Drain System -Turbine Building Drains and Oily Water Separator Trench (in transformer yard) to remove drain line piping Soil Sample Locations F8991073S0001SS to F8991073S0006SS Gamma Scan Locations F8991073S0001GS to F8991073S0006GS Page 2 of 4 Att. 1 Maps F8991073
0IQ S001OSS 0S0010GS S0009SS SD007SS F90S0011GSS3*0, S0009GS S0007GS J
S001G0008GS Map F8991073-2, Clean Drain System - Turbine Building 00Drains and Oily Water Separator pn oo
~Trench (in transformer yard) to remove drain line pipn
~Soil Sample Locations F8991073S0007SS to F8991073S0011SS Gamma Scan Locations F8991073SO007GS to F8991073S0011GS
00 I'D C0 Instrumentation March 19, 2008 Survey Unit F8991073
Table 2-1. Survey Unit Instrumentation Detector Detector Serial MDC Instrument Model No.
No.
HPGe N/A 9987008 Soil - 6.37E-02 pCi/g Cs-137 Soil - 6.23E-02 pCi/g Co-60 Soil - 5.48E-02 pCi/g Cs-137 HPGe N/A 5Soil
- 5.62E-02 pCi/g Co-60 M2350; 193700 SPA-3; 404397 Soil - 5.2 pCi/g Cs-137 2
M2350; 142509 44-157; 201151 1,680 dpm/lOO CM (static MDC)
Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value SPA-3 Investigation Criteria - Scan 16,000 cpm All DCGLw 51.2 Cs-137 All___ _
D_
12.6 Co-60 All DCGLEMc N/A Page 2 of 2 Att. 2 Instrumentation F8991073 Investigation March 19, 2008 Survey Unit F8991073 (none required)
Data Assessment March 19, 2008 Survey Unit F8991073
F8991073 Quantile Plot Cs1 37 DCGL = 51.2 pCVg (TI 00 0.090 0.080 0.070 0.060 u
O) 0.050
>_ 0.040 0.030 0.05 0.020 0.010 0.000 0
20 40 60 80 100 Percentile
- -Activity -
Median --
- 75th Percentile.....
50th Percentile
0 A-F8991073 Scatter Plot Csl37 DCGL = 51.2 pCIIg A
CD M
00 0
U 8;00E-02 7.OOE-02 6.00E-02 5.00E-02 4.00E-02 3.OOE-02 2.OOE-02 1.OOE-02 O.OOE+0O 0
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tx tx Bins - Upper End Value (pCi/g)