ML090830324
| ML090830324 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 01/05/2009 |
| From: | Tallman D Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097, F8100031 | |
| Download: ML090830324 (20) | |
Text
Rancho Seco Final Status Survey Summary Report December 29, 2008 Tank Farm N.E. Quadrant - Surface Soil Survey Unit F8100031 Prepared By: Dan A. Tallman - Date: January 5, 2009 FSS Engineer Reviewed By: \ Date: i-*-O*
Lead FSS Engineer Approved By: Date: - -
Dismantlement S erintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F810003 1, Tank Farm N.E. Quadrant - Surface Soil Survey Unit
Description:
Operating History: This area, traditionally referred to as the Tank Farm, surrounded the tanks used to store radioactive liquids. Subsequent to plant operations, this area was used for the storage of radioactive material and equipment, include that used to perform the demolition of the reactor building concrete structures. Operating records and the HSA document several events with the potential for a release of radioactivity associated with this survey area. The HSA documented the storage of radioactive material within the area that may have had the potential to contaminate the area.
Site Characterization: Soil samples were collected and analyzed for the presence of plant-derived radionuclides. Cs-137 was the primary nuclide of plant origin detected with a mean activity level of 379 pCi/g and a maximum value of 1,040 pCi/g. Based on the classification procedure (DSIP-0020) and levels of Cs-137 reported, the area was determined to be a Class 1 land area.
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 1942 m2 were scanned for 100% coverage. Soil samples were collected at each direct measurement location and analyzed by HPGe detector with the exception of two asphalt locations, which were analyzed using the InSpector with a 2" by 2" Nal 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 F8100031
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area: F810 Tank Farm N.E. Quadrant -
Surface Soil Survey Unit: 0031 Open Land Area Class: 1 LTP Table 5-4 SU Area (m2): 1942 Evaluator: D.A.Tallman DCGL Cs137 surrogate (pCi/g): 51.2 Area Factor: .1.2 Class 1 Design DCGLemc (pCi/g): 61.5 Class 1 LBGR (pCi/g): 25.6 Default = 50% DCGL Design Sigma (pCi/g): 10.7 DTBD-06-001, Table 5-4D Type I Error: 0.05 Type II Error: 0.05 Nuclide: Cs137 Sample Area (m2): 100 Class 1 Total Area Scanned (m2): 1942 Scan Coverage (%): 100% Class I Zi_.a: 1.645 Z1_*: 1.645 Sign P: 0.97725 Calculated Relative Shift: 2.3 Relative Shift Used: 2.3 Uses 3.0 if Rel Shift >3 N-Value: 12 Design N-Value + 20%: 15 NUREG-1575 Table 5-5 Grid Spacing L: 10 Class 1 Page 3 of 7 FSS Summary Report F8100031
Survey Results:
A total of 22 direct measurements were made in F8100031. The results including mean, median, standard deviation and range are shown in Table 2. All of the direct measurements were less than the DCGL. Fourteen (14) 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: 4.47E-01 7 Median:~ 2.94E-01 ~ :j Standard Deviation: 4.34E-01 ________......... _.....
Range: 5.60E-02 to 1.74E00 F8100031SO001SS 5.73E-02 6.54E-02 3.92E-02 F8100031SO002SS 6.11E-02 1.11EOO 9.82E-02 F8100031SO003SS 6.37E-02 < 6.37E-02 F8100031A0004GD 9.39E-01 < 9.39E-01 F8100031S0005SS 5.25E-02 8.15E-02 3.79E-02 F8100031 SO006SS 6.77E-02 1.74E00 1.18E-01 F8100031SO007SS 6.37E-02 4.26E-01 6.94E-02 F8100031S0008SS 5.94E-02 5.43E-01 7.30E-02 F8100031S0009SS 5.64E-02 2.70E-01 5.49E-02 F8100031SO010OSS 5.69E-02 1.58E-01 4.65E-02 F8100031S0011SS 5.40E-02 3.18E-01 5.65E-02 F8100031SO012SS 4.70E-02 1.16E-01 3.83E-02 F8100031SO013SS 7.06E-02 5.45E-01 7.78E-02 F8100031S0014SS 5.73E-02 4.42E-01 6.62E-02 F8100031S0015SS 6.80E-02 7.52E-01 8.39E-02 F8100031SO016SS 5.60E-02 < 5.60E-02 3.50E-02 F8100031SO017SS 5.93E-02 1.99E-01 5.05E-02 F8100031S0018SS 5.93E-02 1.71E-01 4.90E-02 F8100031S0019SS 7.25E-02 5.86E-01 7.89E-02 F8100031SO02OSS 6.OOE-02 1.67E-01 4.96E-02 F8100031S0021SS 8.41E-02 < 8.41E-02 F8100031A0022GD 9.89E-01 < 9.89E-01 Page 4 of 7 FSS Summary Report F8100031
Survey Unit Data Assessment:
The survey design required 22 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 F8100031
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N): 22 Median (pCi/g): 2.94E-01 Mean (pCi/g): 4.47E-01 Standard Deviation (pci/g): 4.34E-01 Maximum (pCi/g): 1.74E00 Sign Test Final N Value: 22 S+ Value: 22 Critical Value: 15 Sufficient Samples Collected: Yes Maximum Value < DCGL: Yes Median Value < DCGL: Yes Mean Value < DCGL: Yes Maximum Value < DCGLemc: Yes Class 1 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 F8100031
Survey Unit Investigations and Results:
Fourteen (14) investigations (scan grids 2, 3, 18/19, 31/32, 35, 43, 62, 96, 105-107, &
118-120) were required for the scan measurements and the results are reported in . The EMC unity rule was not exceeded as shown in Table 3-1.
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 1 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. The potential areas of elevated activity were.
detected and evaluated as shown in Attachment 3. Therefore the EMC criterion was met.
==
Conclusion:==
The FSS of this survey unit was properly designed as a Class 1 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 investigations required were performed and reported in attachment 3.
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 F8100031 meets the release criteria of 10CFR20.1402.
Page 7 of 7 FSS Summary Report F8100031
Attachment 1 Maps December 29, 2008 Survey Unit F8100031
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Attachment 2 Instrumentation December 29, 2008 Survey Unit F8100031
Table 2-1. Survey Unit Instrumentation Instrument Detector Detector Serial MDC Model No. No.
HPGe N/A 05069128 Soil - 0.073 pCi/g Cs-137 Soil - 0.078 pCi/g Co-60 Asphalt - 0.989 pCi/g Cs-137B Inspector N/A 08051294 Asphalt - 1.00 pCi/g Co-60B 2350-1 / 193700 256101 2350-1 / 193715 171374 2350-1/203481 171992 2350-1 /203482 211672 A Ludlum 2350-1 with Nal Detector MDA /investigation level sufficient to detect a 1 uCi discrete Co60 particle as detailed in "Discrete Particle Detection Using the Ludlum 2350-Im and 5.08 by 5.08 Nal detectors" RFD 3/27/07.
B Inspector 1000 with NaI Detector MDA level to meet 10% of DCGLw of 51.2 pCi/g Cs137 equivalent.
c Ludlum 2350-1 w/ Nal detector (44-10/SPA-3) MDA for distributed soil activity 6 pCi/g.
Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value HPGe Investigation Criteria- 61.5 pCi/g Cs 37 surr. 1 Direct - Soil Sample Inspector Investigation Criteria- 6 Gamma I r Direct 61.5 pCi/g Cs137 surr.
2350-1/44-10 Investigation Criteria - 2,3 Scan- Surface Soil All DCGLw 51.2 Cs-137 12.6 Co-60 All DCGLEMC 61.5 pCi/g Cs137 surr.I LTP Chapter 5, Table 5-7, Investigation Levels for Class I Survey units = DCGLEMC - 61.5 pCi/g Cs1 37 2 Ludlum 2350-1 with NaI Detector MDA /investigation level sufficient to detect a 1 uCi discrete Co60 particle as detailed in "Discrete Particle Detection Using the Ludlum 2350-Im and 5.08 by 5.08 Nal detectors" RFD 3/27/07.
3 2350-1/44-10 Investigation Level calculated IAW DSIP-0510 (encl. 8.6)
Page 2 of 2 Att. 2 Instrumentation F8100031
Attachment 3 Investigation December 29, 2008 Survey Unit F8100031
Table 3-1 Survey Unit Investigation Investigation Elevated Area Investigation DCGLemc nvsgaon Initial Investigation niilVleValue Result Area (ic) Facto Grid Level (cpm) (cpm) (pCi/g) Areai(mt) Factor Result_(pi/g)_Fraction 02 8600 11043 0.108 NA NA NA <DCGLw NA 03 8600 ( 10362 0.141 NA NA NA <DCGLw NA
.18/19 3 8600 10936 < 0.911 NA NA NA <DCGL [ NA 31 8600 8694 <8600 cpm i NA NA NA [ <DCGLw NA 35 8600 [ 9226 <0.96 NA, NA NA <DCGL, NA 43 8600 [ 8754 <1.11 NA I NA NA <DCGLw NA 62 8600 10628 <1.05 NA [ NA NA <DCGL L NA 96 8600 519000 <8600 cpm 2 NA I NA NA <DCGL, NA 105 8600 9100 <1.02 ( NA NA NA <DCGL, NA 106 8600 9134 <1.03 NA NA NA <DCGLw NA 107 8600 8618 <0.97 NA NA NA <DCGL, NA 118 8600 9746 <1.07 NA NA NA <DCGLw NA 119 8600 9152 <1.07 NA NA NA <DCGLw NA 120 8600 8659 <1.06 NA NA NA <DCGL, NA Survey Unit Remainder DCGL SU Mean NA EMC Unity Sum NA 1 During scan, Metal Fragment isolated and collected (0.46 uCi Co60), post scan < 8600 cpm 2 During scan, Concrete debris (- 50 gram) isolated and counted (InSpector - 0.027 uCi Eu152), post scan < 8600 cpm 3 Discovery location at/adjacent to scan grid boundary Page 2 of 2 Att. 3 Investigation F8100031
Attachment 4 Data Assessment December 29, 2008 Survey Unit F8100031
F8100031 Quantile Plot Cs137 DCGL = 51.2 pCi/g 2.000 1.800
-o (D
1.600 1.400 1.200 1.000 00 0.800 0.600 0.400 0.294 0.200 CL) 0.000 uj, 0 20 40 60 80 100 Percentile
- Activity - Median - - - 75th Percentile ..-- 50th Percentile
0 F8100031 Scatter Plot C91 37 DCGL = 51.2 pCIg 2.00E+00 c/-t . . -
. - . - - - - - - - - - - - - - - - -1.749 4t1 1.50E+00 ci o 1.OOE+00 - 0 5.0012-01 2- - - oO4 0 0 0 0 c-41 O.OOE+00 0 o 000 0
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Measurement Locations 0 ActMIy - Average" - "+3StDev" -- t-3SeDev" 00
F8100031 Frequency Plot Cs1 37 DCGL = 51.2 pCi/g 12 11 10 0n 9 H 8 7
C 6 0
5 4
3 2
1 0
& 0 N4 X5ý1 A
N-ITI Bins - Upper End Value (pCi/g) 00
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