ML081610155
| ML081610155 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/03/2008 |
| From: | Stein M Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| F8000041 | |
| Download: ML081610155 (18) | |
Text
Rancho Seco Final Status Survey Summary Report April 3, 2008 Central N-S Transit Industrial Area Survey Unit F8000041 Prepared Reviewed Date:
Date:
- '/
Lead FSd'Engineer Approved By:
7/
0 Date:_ __ _-
Dismantlement Superintendent, Radiological'
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8000041, Central N-S Transit Industrial Area 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 679 m2 were scanned for approximately 10%
coverage. Soil samples were collected at direct measurement locations where soil was present and analyzed by HPGe detector. Gamma spectroscopy field measurements were obtained with a Nal detector at direct measurement locations where either asphalt or concrete was present. 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 F8000041
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area:
F800 Central N-S Transit Industrial Area Survey Unit:
0041 Open Land Area Class:
3 LTP Table 5-4 SU Area (m2):
6634 Evaluator:
Michael Stein 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-B Type I Error:
0.05 Type II Error:
0.05 Nuclide:
Cs137 Sample Area (m2):
N/A Class 3 Total Area Scanned (m2):
679 Scan Coverage (%):
10.2%
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 F8000041
Survey Results:
A total of 14 direct measurements were made in F8000041. The results including mean, median, standard deviation and range are shown in Table 2. All of the direct measurements were less than the DCGL. Soil samples (SS) and gamma idirect (GD) measurements were counted to the MDCs 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:
6.65E-1 Median:
8.29E-01 1
Standard Deviation:w 3.38E-01 Range:
5.00E-02 to 8.96E-01 F8000041 A0007GD 8.65E-01
< 8.65E-01 F8000041 A0013GD 8.96E-01
< 8.96E-01 F8000041 A0009GD 8.23E-01
< 8.23E-01 F8000041 A0008GD 7.96E-01
< 7.96E-01 F8000041 AN011GD 8.70E-01
< 8.70E-01 F8000041 A0014GD 8.31E-01
< 8.31E-01 F8000041 A0003GD 8.26E-01
< 8.26E-01 F8000041 AOOO1GD 8.62E-01
< 8.62E-01 F8000041 A0012GD 8.85E-01
< 8.85E-01 F8000041 C0006GD 6.27E-01
< 6.27E-01 F8000041 A0005GD 8.69E-01
< 8.69E-01 F8000041SO004SS 5.54E-02
< 5.54E-02 F8000041SOO1OSS 5.OOE-02
< 5.OOE-02 F8000041SO002SS 5.26E-02,
< 5.26E-02 Page 4 of 7 FSS Summary Report F8000041
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, both values of sigma result in a relative shift of greater than 3 so no additional samples were required.
Page 5 of 7 FSS Summary Report F8000041
Table 3. Data Assessment Results Survey Results Parameter Value.
Comment Actual Direct Measurements (N):
14 Median (pci/g):
8.29E-01 Mean (pCi/g):
6.65E-01 Standard Deviation (pci/g):
3.3 8E-0 1 Maximum (pci/g):
8.96E-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 No additional Samples Required Pass the Sign Test?
Yes Reject the Null Hypothesis?
Yes The survey unit passes all conditions?
Investigate Survey Unit Passes Page 6 of 7 FSS Summary Report F8000041
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), 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 sample standard deviation was greater than the design standard deviation. However, both values of sigma result in a relative shift of greater than 3 so no additional samples were required.
==
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.
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 F8000041 meets the release criteria of 10CFR20.1402.
Page 7 of 7 FSS Summary Report F8000041
Attachment I Maps April 3, 2008 Survey Unit F8000041
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1416882.8 INDUST.AREA CENTRAL N-S.. TRAANSIl soiL.SAMPLE/GAMMA DIRECT ACTIVITY MEASUREMENT LOCATIONS F8000041 -M2 FU,~ 5000304-RCr RkyM
CD 00 00 C0
-1, r..r INDUST AREA CENTRAL N-S TRANSIT GAMI4 SCAN ACTIVITY MEASUREMENT LOCATIONS F800G041 -M3 FILE:. Bo*oo4-RC Instrumentation April 3, 2008 Survey Unit F8000041
Table 2-1. Survey Unit Instrumentation Detector Detector Detector SerialMD Instrument Model MDC No.
No.
HPGe N/A 05069128 Soil - 5.54E-2 pCi/g Cs-137 5.88E-2 pCi/g Co-60 Concrete - 6.27E-1 pCi/g Cs-137 6.55E-1 pCi/g Co-60 Inspector N/A 08051294 Asphalt-8.96E-1 pCi/g Cs-137 9.05E-1 pCi/g Co-60 Soil - 2.93E-1 pCi/g Cs-137 2.31E-I pCi/g Co-60 Concrete-3.31E-1 pCi/g Cs-137 ISOCS N/A 2983947 2.28E-1 pCi/g Co-60 Asphalt-3.19E-1 pCi/g Cs-137 2.46E-1 pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value ISOCS Investigation Criteria - Scan 20 pCi/g Cs-137 51.2 Cs-137 All DCGLw
'12.6 Co-60 All DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8000041
Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model MDC No.No.
HPGe N/A 05069128 Soil - 5.54E-2 pCi/g Cs-137 5.88E-2 pCi/g Co-60 Con'crete - 6.27E-1 pCi/g Cs-137 6.55E-1 pCi/g Co-60 Inspector N/A 08051294 Asphalt -
8.96E-1 pCi/g Cs-137 9.05E-1 pCi/g Co-60 Soil - 2.93E-1 pCi/g Cs-137 2.31E-i pCi/g Co-60 Concrete-3.31E-1 pCi/g Cs-137 ISOCS N/A 2983947
. 2.28E-1 pCi/g Co-60 Asphalt-3.19E-1 pCi/g Cs-137 2.46E-l pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value ISOCS Investigation Criteria - Scan 20 pCi/g Cs-137 52.6 Cs-137 All DCGLw 12.6 Co-60 All DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8000041 Investigation April 3, 2008 Survey Unit F8000041 (none required)
Data Assessment
-April 3, 2008 Survey Unit F8000041
0 CD?
00 F8000041 Quantile Plot Cs1 37 DCGL =51.2 pCi/g U
U 1.000 0.900 0.800 0.700 0.600 0.500 0.400 0.300 0.200 0.100 0.000 0.828 0
- 20.
40 60 80 Percentile 100 I +
Activity --
Median -
- - 75th Percentile ----
50th Percentile I
0*
CD F8000041 Scatter Plot Cs13? DCGL 61.2 pClIg 2.Q 0E+OO.........
1.50E+00
- 1.00E*00 0
0 0
0 0
0 2; 6.00E-01 O.OEOO0 0
0
.C E 0
e e
e e
e e
e
- .4
-5.00E-01 I
I Measurement Locations 0
ActIviR-Average --
"+3StDev"
-3StDev" 00 0
O0 0
0
00 C)
C>~
C0 C0
- P F8000041 Frequency Plot Cs1 37 DCGL = 51.2 pCi/g C:
0 10 9
8 7
6 5
4 3
2 1
0 Bins - Upper End Value (pCi/g)