ML090830320
| ML090830320 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/19/2008 |
| From: | Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097, F8000101 | |
| Download: ML090830320 (17) | |
Text
Rancho Seco Final Status Survey Summary Report March 19, 2008 Industrial Area Central Yard - North and East of Maintenance Building Survey Unit F8000101 Prepared ByC: c 4*ý Date:____
Reviewed By: Date: 4/z4i.
Approved By: 7,1 Date: Z -0 Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8000101, Industrial Area Central Yard - North and East of Maintenance Building Survey Unit
Description:
Operating History: This area covers the majority of Industrial Area soils exclusive of the building footprints and rail line in this area. Operating records and the HSA document no specific release of radioactivity in these survey areas however this area does border known contaminated areas. The HSA recorded no specific unplanned release events.
Site Characterization: Soil and sediment samples were collected and analyzed for the presence of plant-derived radionuclides. Cs-137 was the only detected nuclide of plant origin with a mean activity level of 0.062 pCi/g and a maximum value of 0.299 pCi/g.
(Site background levels of Cs-137 have been determined to be approximately 0.312 pCi/g.) As described in section 2 of the LTP, the area was evaluated using DSIP-0020 and was designated as Class 3.
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 508 m2 were scanned for approximately 32%
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 F80001 01
Table 1. 'Survey Unit Design Parameters Survey Design Parameter[ Value Comment Survey Area: F800 Industrial Area Central Yard - North and East of Maintenance Building Survey Unit: 0101 Open Land Area Class: 3 LTP Table 5-4 SU Area (m2): 1587 Evaluator: Gary Frank 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): 0.01 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): 508 Scan Coverage (%): 32% Class 3 Zl-, :
1.645 ZI-P : 1.645 Sign P: 0.99865 Calculated Relative Shift: 2560 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 F80001 01
Survey Results:
A total of 15 direct measurements were made in F8000101. 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 with all results less or equal to MDC. The MDC for Cs-137 is 0.357 pCi/g and for Co-60 0.is 316 pCi/g. Soil samples were counted to the MDC shown in Table 2-1 of Attachment 2.
Table 2. Direct Measurement Results (all activity values in pCi/g)
Measurement ID Cs137 MDA Cs137 Activity Uncertainty Mean: ' ~ ~7.98E-01 7~
Median: 8.5 8E-0 1 Standard DeviatiOn: , x. 2.19E-01 Range: 4.73E-02 to 9.42E-01 F8000101AOOO1GD 8.09E-01 < 8.09E-01 F80001OIA0002GD 8.14E-01 < 8.14E-0t F80001OIA0003GD 8.07E-01 < 8.07E-01 F80001OIA0004GD 8.97E-01 < 8.97E-01 F80001OIA0005GD 8.99E-01 < 8.99E-01 F8000IO1AO006GD 8.38E-01 < 8.38E-01 F80001O1AO007GD 8.75E-01 < 8.75E-01 F80001O1AO008GD 8.73E-01 < 8.73E-01 F80001OIA0009GD 6.52E-01 < 6.52E-01 F80001O1A001OGD 8.71E-01 < 8.71E-01 F8000101AOO11GD 8.55E-01 < 8.55E-01 F8000101AOO12GD 8.58E-01 < 8.58E-01 F80001O1A0013GD 9.32E-01 < 9.32E-01 F80001O1A0014GD 9.42E-01 < 9.42E-01 F8000101SOOO1SS 4.73E-02 < 4.73E-02 Page 4 of 7 FSS Summary Report F80001 01
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 greater than the design standard deviation, but both values of sigma resulted in a relative shift greater than three (3), no additional samples were required.
Page 5 of 7 FSS Summary Report F8000101
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N): 15 Median (pCi/g): 8.58E-01 Mean (pCi/g): 7.98E-01 Standard Deviation (pCi/g): 2.19E-01 Maximum (pCi/g): 9.42E-01 Sign Test Final N Value: 15 S+ Value: 15 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 <0.5 DCGL Pass the Sign Test? Yes Reject the Null Hypothesis? Yes The survey unit passes all conditions? Investigate <0.5 DCGL - Survey Passes Page 6 of 7 FSS Summary Report F80001i01
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 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 and the scan -
of the LTP. The required number of direct measurements was made 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 F8000101 meets the release criteria of 10CFR20.1402.
Page 7 of 7 FSS Summary Report F80001 01
Attachment 1 Maps March 19, 2008 Survey Unit F8000101
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Attachment 2 Instrumentation March 19, 2008 Survey Unit F8000101
Table 2-1. Survey Unit Instrumentation Detector, Detector Serial Instrument Model N.MDC Noo.
HPGe N/A 05069128 Soil - 0.0473 pCi/g Cs- 137 Inspector N/A 08051294 Asphalt - 0.942 pCi/g Cs-137 Soil - 0.271 pCi/g Cs-137 ISOCS N/A 1983920 Soil - 0.156 pCi/g Co-60 Asphalt - 0.3 57 pCi/g Cs-i137 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value Soil - 26.3 pCi/g Cs-137 ISOCS Investigation Criteria - Scan Soil - 6.3 pCi/g Co-60 Asphalt - 26.3 pCi/g Cs-137 Inspector Direct Investigation Level - Asphalt -26.3 ~/
Apat-2. s 3 pCi/g Cs-137 HPGe Investigation Level Soil - 26.3 pCi/g Cs-137 Soil - 6.3 pCi/g C6-60 51.2 Cs-137 All DCGLw 12.6 Co-60 All DCGLEMC N/A Page 2 of 2 PAtt. 2 Instrumentation F80001 01
Attachment 3 Investigation March 19, 2008 Survey Unit F8000101 (none required)
Attachment 4 Data Assessment March 19, 2008 Survey Unit F8000101
F8000101 Quantile Plot Cs137 DCGL = 51.2 pCi/g 1.000 0.900 0.858 CE, 0.800 0.700 u 0.600 0.500 00 0.400 0.300 0.200 0.100 C,,
0.000 0 20 40 60 80 100 Percentile I
- Activity - Median - - - 75th Percentile - - - - 50th Percentile I
0 F8000 101 Scatter Plot Cs137 DCGL = 51.2 pClilg 1.601E+00 1.454 1.40E+00 -----------------------------------------------
1.20E+00 U 1.0OE+00
%00 0 *0 0 0 0 0 0 8.O0E-O1 - -- - - - - - - - .0.799 CD) 4.001E-01 CD 2.00E-01 0.00E+00 I I I i i iCo Measurement Locations o Activity - Averacie - - "+3StDev - - "-3SIDev"-
00 0:
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F8000101 Frequency Plot Cs1 37 DCGL = 51.2 pCi/g 14 13 12 11 10 U- 9 C)
U- 8 7
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('3 5
4 3
2 1
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-V. Cb Bins - Upper End Value (pCi/g) 00