ML090830319
| ML090830319 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 02/12/2009 |
| From: | Tallman D A Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097, F8000072 | |
| Download: ML090830319 (20) | |
Text
Rancho Seco Final Status Survey Summary Report February 12, 2009 Western IA (Barrel Farm west)Survey Unit F8000072 Prepared By: Dan A. Tallman J 1 Z- Date: February 12, 2009 FSS Engineer Reviewed By 7 _L Date: -Z q Lead FSS Engineer Approved By: Date: 3-,3-Dismantlement Superintendent, Radiological FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit: F8000072, Western IA (Barrel Farm west)Survey Unit
Description:
Operating History: This area is located on the west side of the Industrial Area to the north of the retention basins and south of the IOSB. Specifically, -700 square meters west of the historic location of the barrel omitted from survey coverage in F8000071 and F8000121.
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.
Radioactive material may have been temporarily stored in this area.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 plantorigin 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 mays in Attachment
- 1. Direct measurement locations were randomly determined and 35 m were scanned for approximately 5%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 F8000072 Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area: F800 Western IA (Barrel Farm west)Survey Unit: 0072 Open Land Area Class: 3 LTP Table 5-4 SU Area (M 2): 696 Evaluator:
D.A. Tallman 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): 0.034 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 (Mn 2): 35 Scan Coverage (%): 5% Class 3 1.645 1.645 Sign P: 0.99865 Calculated Relative Shift: 752.9 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 F8000072 Survey Results: A total of 14 direct measurements were made in F8000072.
The results including mean, median, standard deviation and range are shown in Table 2. All of the direct measurements were less than the DCGL. One of the scan measurements indicated areas of elevated activity.
The observed scan range was 8482-11076 cpm. 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: 6.87E-02 Median:
6.74E-02 1. !Standard Deviation:
9.42E-03 Range: 5.57E-02 to 8.56E-02 F8000072SOOO1SS 8.56E-02 < 8.56E-02 F8000072S0002SS 7.04E-02 < 7.04E-02 F8000072S0003SS 5.76E-02 < 5.76E-02 F8000072S0004SS 7.98E-02 < 7.98E-02 F8000072S0005SS 7.66E-02 < 7.66E-02 F8000072S0006SS 6.50E-02 < 6.50E-02 F8000072S0007SS 6.62E-02 < 6.62E-02 F8000072S0008SS 6.46E-02 < 6.46E-02 F8000072S0009SS 6.22E-02 < 6.22E-02 F8000072S001OSS 5.63E-02 < 5.63E-02 F8000072SOO11SS 6.86E-02 < 6.86E-02 F8000072S0012SS 8.07E-02 < 8.07E-02 F8000072S0013SS 7.20E-02 < 7.20E-02 F8000072S0014SS 5.57E-02 < 5.57E-02 Page 4 of 7 FSS Summary Report F8000072 Survey Unit Data Assessment:The survey design required 14 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 F8000072 Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N): 14 Median (pCi/g): 6.74E-02 Mean (pCi/g): 6.87E-02 Standard Deviation (pCi/g): 9.42E-03 Maximum (pCi/g): 8.56E-02 Sign Test Final N Value: 14 S+ Value: 14 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: Yes Pass the Sign Test? YesReject the Null Hypothesis?
Yes The survey unit passes all conditions?
Yes Page 6 of 7 FSS Summary Report F8000072 Survey Unit Investigations and Results: One investigation (scan grid # 02) was required for the scan measurements and the results are reported in Attachment 3.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 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. One potential area of elevated activity was detected and evaluated as shown in Attachment 3.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. One investigation was 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 F8000072 meets the release criteria of 1OCFR20.1402.
Page 7 of 7 FSS Summary Report F8000072 Attachment I Maps February 12, 2009 Survey Unit F8000072 t'D 00 CI)C)7 _____________
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-Attachment 2 Instrumentation February 12, 2009 Survey Unit F8000072 Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model No.MDC No.2350-1 44-10 171374 5-6 pCi/g for distributed soil Soil -0.086 pCi/g Cs-137 e Soil -0.07 pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value HPGe Investigation Criteria -Direct Soil -25.6 pCi/g Cs-137(suIr) 2350-1/44-10 Investigation Criteria-Scan 9750 cpm'All DCGLw 51.2 Cs-137 12.6 Co-60 2350-1/44-10 Investigation Level calculated lAW DSIP-0510 (encl. 8.6)Page 2 of 2 Att. 2 Instrumentation F8000072 Attachment 3 Investigation February 12, 2009 Survey Unit F8000072 Table 3-1 Survey Unit Investigation DCGLemnc d Investigation Initial Value Investigation Elevated Area Investigation Unity InvResult Area (mC) Factor Result (pCi/g) Fraction Level (cpm) (cpm) (pCi/g)02 9750 11076 MDA 1 NA NA NA MDA NA DCGL = SU Mean =Survey Unit Remainder 51.2 0.068 NA 1 MDA values -Co60 < 0.05 pCi/g, Cs137 < 0.065 pCi/g EMC Unity Sum NA Page 2 of 2 Att. 3 Investigation F8000072 Attachment 4 Data Assessment February 12, 2009 Survey Unit F8000072 F8000072 Quantile Plot Cs137 DCGL = 51.2 pCi/g 0.090 0.080 f ---I 0..067 0.070* J.0 .0 6 0 t, ,---0.020 II 0.000 0 20 40 60 80 100 Percentile S Activity Median 75th Percentile
-50th Percentile 00 i'.J (D 0-C)~Ca Ca C0 F8000072 Scatter Plot F8000072 Scatter Plot Cs137 DCGL = 51.2 pClIg 1.20E-01 1.OOE-01 -- ------------------------------
.
097 Se 8.00E-02 -0 6.OOE-02 -0 4.00E-02 -- --------------------------------
D--04 2.00E-02 0.00E+00 i i Measurement Locations 0 Activity -Averaqe --"+3StDev I -.-3StDev I Ud)C,)00 F8000072 Frequency Plot Cs1 37 DCGL = 51.2 pCi/g 6-5-4-)3-2-I 0+Co.A$C&Bins-Upper End Value (pCi/g)