ML090830548
| ML090830548 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 01/07/2009 |
| From: | Ellen Brown Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097, F8080033 | |
| Download: ML090830548 (18) | |
Text
Rancho Seco Final Status Survey Summary Report January 7, 2009 Cooling Tower Buffer (East)
Survey Unit F8080033 Prepared By: t z i Date: C/7/2&o FSS Engineer Reviewed By: * *Date:
-44 I I 09 Lead FSS Engineer Approved By: -7 Date: -0 Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8080033, Cooling Tower Buffer (East)
Survey Unit
Description:
Operating History:'The cooling towers and basins were part of the condenser cooling water system. The paved area comprising the basins was not reported to have been used for the storage of radioactive material. Operating records and the HSA document one event with the potential for a release of radioactivity associated with this survey area.
Site Characterization: Direct measurements were made of the exterior surfaces of the structure which confirmed the presence of plant-derived radionuclides. Direct structure measurements showed a mean gross activity level of 4,952 dpm/100 cm2 and a maximum value of 6,289 dpm/1 00 cm2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the area was determined to be a Class 2 area.
HSA Events: PDQ-930036.
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 using a random-start, fixed grid pattern and 1300 m2 were scanned for approximately 20% coverage. 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 F8080033
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area: F808 Cooling Tower Buffer (East)
Survey Unit: 0033 Open Land Area Class: 2 LTP Table 5-4 SU Area (m2): 6481 Evaluator: Erin L. Brown 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): 0.92 LTP Table 5-4C, Rev. No. 1 Type I Error: 0.05 Type II Error: 0.05 Nuclide: Cs137 Sample Area (m2): 462.9 Class 2 Total Area Scanned (m2): 1300 Scan Coverage (%): 20.1% Class 2 1.645 ZI-P :1.645 Sign P: 0.99865 Calculated Relative Shift: 27.8 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: 21.5 Class 2 Page 3 of 7 FSS Summary Report F8080033
Survey Results:
A total of 16 direct measurements were made in F8080033. 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 46 ISOCS scans were less than or equal to the MDC values listed in Table 2-1.
Table 2. Direct Measurement Results (all activity values in pCi/g)
Measurement ID Cs137 MDA Cs137 Activity Uncertainty Mean: ~' K9.52E-01 ;K Median: 9.68E-01..
Standard Deviation: 3.63E-02 '> ,
Range: 8.84E-01 to 1.OOEOO F8080033 A0009GD 9.04E-01 < 9.04E-01 F8080033 A0008GD 9.03E-01 < 9.03E-01 F8080033 A0007GD 8.97E-01 < 8.97E-01 F8080033 A0006GD 9.69E-01 < 9.69E-01 F8080033 A0005GD 9.36E-01 < 9.36E-01 F8080033 A0004GD 9.53E-01 < 9.53E-01 F8080033 A0003GD 9.63E-01 < 9.63E-01 F8080033 A0002GD 9.69E-01 < 9.69E-01 F8080033 AOOO1GD 9.93E-01 < 9.93E-01 F8080033 A0016GD 9.73E-0i < 9.73E-01 F8080033 A0015GD <9.80E-01 9.80E-01 F8080033 A0014GD 9.66E-01 < 9.66E-01 F8080033 A0013GD 1.00E00 < L.OOEOO F8080033 A0012GD 9.69E-01 < 9.69E-01 F8080033 A0011GD 9.80E-01 < 9.80E-01 F8080033 A0010GD 8.84E-01 < 8.84E-01 Page 4 of 7 FSS Summary Report F8080033
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 F8080033
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N): 16 Median (pci/g): 9.68E-01 Mean (pCi/g): 9.52E-01 Standard Deviation (pCi/g): 3.63E-02 Maximum (pCi/g): 1.OOEOO 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 F8080033
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 2 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 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 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 F8080033 meets the release criteria of 10CFR20.1402.
Page 7 of 7 FSS Summary Report F8080033
Attachment 1 Maps January 7, 2009 Survey Unit F8080033
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[0 681.3832E 1889250N T 6813873E 1889248N KEY PLAN 681.3454E I89207N\
I I IOOO~JEN 6813454E 6813574E 00 00 1888915N 1888915N o 5 10 1520 23 COOLING TOWER BUFFER SCALE METERS (9 a
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COOLING TOWER BUFFER GAMMA DIRECT MEASUREMENT LOCATIONS SACRAMENTO MUNICIPAL UTILITY DISTRICT F8080033-M2
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- SACRAMENTO MUNICIPAL UTILITY DISTRICT F8080033-M3 FiLE: 80.80,0102 RC RAYMOND' OLE 80800302 PC RAYMOND
Attachment 2 Instrumentation January 7, 2009 Survey Unit F8080033
Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model No. MDC No.
1.OOEOO pCi/g Cs-137 Inspector N/A 08051294 1.01E00 pCi/g Co-60 3.61E-01 pCi/g Cs-137 ISOCS N/A 1983920 2.65E-01. pCi/g Co-60 3.37E-01 pCi/g Cs-137 ISOCS N/A 2983947 2.50E-01 pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value ISOCS Investigation Criteria - Scan 23 Cs-137 All DCGLw 51.2 Cs-137 12.6 Co-60 All DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8080033
Attachment 3 Investigation January 7, 2009 Survey Unit F8080033 (none required)
Attachment 4 Data Assessment January 7, 2009 Survey Unit F8080033
F8080033 Quantile Plot Cs137 DCGL = 51.2 pCi/g 1.020 1.000 0.980 0.968 0.960 0.940
.5 0
0.920 rJ2 0.900 0.880 0.860 0 20 40 60 80 100 Percentile Activity - Median - - -75th Percentile - - - - 50th Percentile 00 00
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F8080033 Scatter Plot Cs137 DCGL = 51.2 pClIg 1.20E+00 1.a81 1OOE+00 __. _ _ __ ___ _ .2.. mo -. 0.952 0 0 00 S8.-E--1 - 0.843 U
6.OOE-01
- 4.OOE-01 2.00E-01 0.OOE+000 00 Measurement Locations 7
o 0 Activity - Average - - "+3SIDev" - - -3StDev i 00 00
F8080033 Frequency Plot Cs1 37 DCGL = 51.2 pCi/g 6
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Bins - Upper End Value (pCi/g) 00