ML090980395
| ML090980395 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 05/12/2008 |
| From: | Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097 | |
| Download: ML090980395 (17) | |
Text
Rancho Seco Final Status Survey Summary Report May 12, 2008.
RHUT 8" Line Survey Unit F8991.093 Prepared By:_ ___ Date:
Reviewed By: Date:
Approved By: Z"Date: 3 z Z Dismantlement Sperintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8991093, RHUT 8" Line Survey Unit
Description:
Operating History: This system provided an alternate pathway for delivering feed water to the steam generators. This system was reported to have been contaminated as a result of steam generator primary to secondary tube leaks. 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 which confirmed the presence of plant-derived radionuclides. Direct measurements of the interior showed a mean gross activity level of 368 dpm/100 cm2 and a maximum value of 634 dpm/1 00 cm2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the system was determined to be a Class 3 system.
Due to the difficulty of surveying this system, and the potential for system leakage, the system piping was removed and the resulting trench was surveyed. While the characterization data supported a Class 3 designation, the trench was conservatively determined to be Class 2.
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 randomly determined and 110 m2 were scanned for approximately 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 F8991093
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area: F899 RHUT 8" Line Survey Unit: 1093 Open Land Area Class: 2 LTP Table 5-4 SU Area (m2): 110 Evaluator: Gary Frank DCGL Cs137 surrogate (pCi/g): 51.2 Area Factor: N/A Class 2 Design DCGLemc (pCi/g): N/A Class 2 LBGR (pCi/g): 25.6 Default = 50% DCGL Design Sigma (pCi/g): 9.83 DTBD-06-001, Table 5-4D Type I Error: 0.05 Type II Error: 0.05 Nuclide: Cs137 Sample Area (m2): 7.3 Class 2 Total Area Scanned (m2): 110 Scan Coverage (%): 100% Class 2 1.645 1.645 Sign P: 0.99379 Calculated Relative Shift: 2.6 Relative Shift Used: 2.6 Uses 3.0 if Rel Shift >3 N-Value: 12 Design N-Value + 20%: 15 NUREG-1575 Table 5-5 Grid Spacing L: 2.7 Class 2 Page 3 of 7 FSS Summary Report F8991093
Survey Results:
A total of 16 direct measurements were made in F8991093. The results including mean, median, standard deviation and range are shown in Table 2. All of the direct measurements were less than the DCGL. All of the scan measurements were below the MDA as shown in Attachment 2. 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 pCig)
Measurement ID Mean:
Median:4 Cs137 MDA Cs'137 Activity 4.06E-02 4.01E-02 I
I Uncertainty Standard Deviation: 3.41 E-03.. ________ .........
Range: 3.57E-02 to 4.91E-02 F8991093S0001SS 3.75E-02 < 3.75E-02 F8991093S0002SS 3.99E-02 < 3.99E-02 F8991093S0003SS 4.31E-02 < 4.31E-02 F8991093S0004SS 3.91E-02 < 3.91E-02 F8991093S0005SS 4.02E-02 K 4.02E-02 F8991093S0006SS 4.18E-02 < 4.18E-02 F8991093S0007SS 3.89E-02 < 3.89E-02 F8991093S0008SS 4.13E-02 < 4.13E-02 F8991093 SO009SS 3.66E-02 < 3.66E-02 F8991093S0010SS 3.57E-02 < 3.57E-02 F8991093S0011SS 4.42E-02 < 4.42E-02 F8991093S0012SS 3.76E-02 < 3.76E-02 F8991093S0013SS 4.22E-02 < 4.22E-02 F8991093S0014SS 4.91E-02 *< 4.91E-02 F8991093S0015SS 4.34E-02 < 4.34E-02 F8991093S0016SS 3.82E-02 1< 3.82E-02 Page 4 of 7 FSS Summary Report F8991093
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 FSS Summary Report F8991093
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N): 16 Median (pCi/g): 4.01E-02 Mean (pCi/g): 4.06E-02 Standard Deviation (pCi/g): 3.41E-03 Maximum (pCi/g): 4.9 1E-02 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: N/A Class 2 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 F8991093
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, the ALARA criterion has been met.
Changes in Initial Survey Unit Assumptions:
The survey unit was designed as a Class 2 land survey and the sample results are consistent with that classification. The variability of the survey results was less thanwere the of elevated activity characterization data used for survey design. No potential areas detected.
==
Conclusion:==
The FSS of this survey unit was properly designed as a Class 2 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 reqcuired.
The direct measurement data support rejection of thenull 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 F8991093 meets the release criteria of 10CFR20.1402.
Page 7 of 7 FSS Summary Report F8991093
Attachment 1 Maps May 12, 2008 Survey Unit F8991093
CD 0
F1 AFFECTEDAREA Stainless steel drain line I"II le 15 14 I) if' II II 171 OILYWATER SEPARATOR ISOCS shots are measured 3 meters center to center MH-013 and at 2 meter height.
6813444E 1888328N 00 RHUT TRENCH 2 ISOCS GAMMA SCANS F8991093 - M1
10 LI AFFECTED AREA 2" Stainless steel drain line 8" drain line directly underneath 68133419E 00 18884 1N Ii (Uj OILYWATER SEPARATOR MH-013 6813444E i$88328N
Attachment 2, Instrumentation May 12, 2008 Survey Unit F8991093
Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model No.MDC No.
HPGe N/A 05069128 Soil - 1.67e-1 pCi/g Cs-137 Soil - 2.95e-1 pCi/g Cs-137 Soil - 2.55e-i pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value Soil - 25.6 pCi/g Cs-137 Investigation Criteria - Scan Soil -26 pCi/g Co-60 ISOCS Soil - 6.3 pCi/g Co-60 All DCGLw 51.2 Cs-137 1 1_ 12.6 Co-60 Page 2 of 2 Att. 2 Instrumentation F8991093
Attachment 3 Investigation May 12, 2008 Survey Unit F8991093 (none required)
Attachment 4.
Data Assessment May 12, 2008 Survey Unit F8991093
F8991093 Quantile Plot Cs137 DCGL = 51.2 pCi/g 0.060 0.050 0
0.040 0.04 C-3 0.030 cjh (n~ 0.020 CD2 0.010 0.000 0 20 40 60 80 100 Percentile
- Activity - Median - - - 75th Percentile - - - - 50th PercentileI 00
0 F8991093 Scatter Plot C9137 DCGL = 51.2 pClIg 6.00E-02 5.00E-02 ----- - - - - - - ------------------------ - - o-0-4 og 4.00E-02 - -- 0"__ 00 0 0 0 0 3.00E-02 --.-.-.----- --------
- ---- ----------------------- 0.03 2 .00E-022 CD 1.GOE-02 1.00E12+0 0,00E+00o I ; I I1 I I op 4b p # 4- - A z 4 4 4 Measurement Locations c0 Activfty_ Average_ - +3SIDev" "-3SlDev.
00 Uj::
(D0 F8991093 Frequency Plot Cs1 37 DCGL = 51.2 pCi/g 8
>7 0 c4 00 0
0 Cf2
<C-r"v Bins - Upper End Value (pCi/g)