ML081610117
| ML081610117 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/01/2008 |
| From: | Tallman D Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| F5010031 | |
| Download: ML081610117 (18) | |
Text
Rancho Seco Final Status Survey Summary Report April 1, 2008 Upper/Outer Laydown Area Survey Unit F5010031 Prepared By: Dan A. Tallman_
Mate:Apeil 1, 2008
,-$7/
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Reviewed By:
Date LeaZFSS Engineer Approved By:
Date:
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F5010031, Upper/Outer Laydown Area Survey Unit
Description:
Operating History: The area, located in the southeastern portion of the upper parking lot north of the main employee parking lot, (the Upper/Outer yard), consists of the fenced pavement surrounding (on three sides) the Hazardous Materials Warehouse plus an apron extending - 40 feet south of the fence line that is also paved except for the eastern 30-40 feet, which is soil. Operating records and the HSA document the potential for a release of radioactivity in this survey area. The HSA recorded two potential release events. One event involved the discovery of a pallet of articles labeled as "Contact RP prior to disassembly outside the RCA". In addition, the area was used as a staging area.for outgoing and incoming radioactive material shipments. The access road over which shipments were made runs through the area.
Site Characterization: These paved areas were surveyed and found to have a maximum mean value of 2,522 dpm/100 cm 2 and a maximum of 3,251 dpm/100 cm 2. Based on the classification procedure (DSIP-0020), the area was determined to be a Class 3 area.
HSA Events: none 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 392 m2 were scanned for approximately 15%
coverage. Direct Gamma spectrums were taken at each direct measurement location using the InSpector 1000 and analyzed by the Canberra Genie 2000 software. 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 F5010031
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area:
F501 Upper/Outer Laydown Area Survey Unit:
0031 Open Land Area Class:
3 LTP Table 5-4 SU Area (m2):
2665 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 (m2):
392 Scan Coverage (%):
14.7%
Class 3 1.645 ZI_0 :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 F5010031
Survey Results:
A total of 14 direct measurements were made in F5010031. The results including mean, median, standard deviation and range are shown in Table 2. All of the direct measurements were less~than theDCGL. 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 pCi/g)
Measurement ID Cs137 MDA Cs137 Activity Uncertainty Mean: '
45j1 7.64E-01 Median:
4 7.69E-0 I Standard Deviation: ~I4.93E-02 Range:
7.OOE-01 to 8.47E-01 F5010031 AOOO1GD 8.35E-01
< 8.35E-01 F5010031 A0002GD 7.72E-01
< 7.72E-01 F5010031 A0003GD 7.97E-01
< 7.97E-01 F5010031 A0004GD 7.97E-01
< 7.97E-01 F5010031 A0005GD 8.06E-0l
< 8.06E-0l F5010031 A0006GD 7.11E-01
< 7.11E-0l F5010031 A0007GD 7.25E-01
< 7.25E-01 F5010031 A0008GD 7.66E-01
< 7.66E-01 F5010031 A0009GD 7.12E-01
< 7.12E-01 F5010031 AOO1OGD 8.47E-01
< 8.47E-01 F5010031 AOO11GD 7.28E-01
< 7.28E-01 F5010031 A0012GD 7.13E-01
< 7.13E-01 F5010031 A0013GD 7.89E-01
<.7.89E-01 F5010031 A0014GD 7.O0E-01
< 7.00E-01 Page 4 of 7 FSS Summary Report F5010031
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 greater than the design standard deviation. However, the use of either value results in a relative shift of greater than 3 and so no additional samples were required.
Page 5 of 7 FSS Summary Report
,F5010031
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N):
14 Median (pCi/g):.
7.69E-01 Mean (pCi/g):
7.64E-01 Standard Deviation (pCig):
4.93E-02 Maximum (pCi/g):
8.47E-01 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:
Investigate Use of Standard Deviation vs. design sigma does not alter the relative shift used to determine the minimum number of direct measurements required.
Pass the Sign Test?
Yes Reject the Null Hypothesis?
Yes The survey unit passes all conditions?
Yes Page 6 of 7 FSS Summary Report F5010031
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 residualactivity 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 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 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 F5010031 meets the release criteria of IOCFR20.1402.
Page 7 of 7 FSS Summary Report F5010031 Maps April 1, 2008 Survey Unit F5010031
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.C f' AYMOND Instrumentation April 1, 2008 Survey Unit F5010031
Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model MDC No.
No.
Asphalt - 0.847 pCi/g Cs-137 Inspector N/A 08051294 Asphalt - 0.781 pCi/g Co-60 Soil - 0.323 pCi/g Cs-137 ISOCS N/A 2983947 Soil - 0.227 pCi/g Co-60 Asphalt - 0.358 pCi/g Cs-137 Asphalt - 0.274 pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value Soil/Asphalt - 5.1' pCi/g Cs-13 7 Inspector Investigation Criteria -
Soil/Asphalt - 5.11 pCi/g Co-60 Direct Measurement Soil/Asphalt-20 pCi/g Cs-137 ISOCS Investigation Criteria - Scan Soil/Asphalt - 5 pCi/g Co-60 51.2 Cs-137 All DCGLW 12.6 Co-60
'Positive identification of Plant derived radionuclides will be investigated.
Page 2 of 2 Att. 2 Instrumentation F5010031 Investigation April 1, 2008 Survey Unit F5010031 (none required)
Data Assessment April 1, 2008 Survey Unit F5010031
CD (D~
F5010031 Quantile Plot Cs137 DCGL = 51.2 pCi/g C-)
0.
C, 0.900 0.800 0.700 0.600 0.500 0.400 0.300 0.200 0.100 0.000 0.769 100 0
20 40 60 Percentile 80
+
Activity
-Median
- - 75th Percentile -
50th Percentile I F5010031 Scatter Plot Cs137 DCGL = 51.2 pClig 1.00E+00
.001E-01
.012 o
0 8.00E-01 o
0 o
0 7.OOE-01 0
0 0o (U 6.00E-01 8).
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I Measurement Locations 0
Activity-Averae-
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-3StIev'7 Ct Uo
0 C12 F5010031 Frequency Plot Csi 37 DCGL = 51.2 pCi/g 6
LL 0
(I2 0
QN V~
N Bins - Upper End Value (pCi/g)