ML090830323
| ML090830323 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 01/08/2009 |
| From: | Tallman D Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097, F8100022 | |
| Download: ML090830323 (19) | |
Text
Rancho Seco Final Status Survey Summary Report January 8, 2009 Tank Farm - N.W. Quadrant Subsurface Soil Survey Unit F8100022 Prepared By: Dan A. Tallman_ _ _ _ _ Date: January 8, 2009 FSS Engideer Reviewed By:12* ate: I( (0ý Lead FSS Engineer Approved By: 7d :L Date: ______
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8100022, Tank Farm - N.W. Quadrant Subsurface 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: As documented in F8100021, surface 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 potential for sub-surface contamination within the unit, the decision to perform an investigation of the sub-surface soil was made. This investigation resulted in the collection of 34 soil samples, the locations of which coincided with those of the surface soil evaluation. The results of these samples and the statistical tests performed are also consistent with the evaluations performed on the surface soil component evaluated in F8100021. Based on the classification procedure (DSIP-0020) and consistent with the classification applied to the surface soil component, the area was designated 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 spatial locations were based on the surface soil locations sampled in F8100021. Sub-Surface samples were then collected at one meter intervals. Samples taken from a depth of-15 cm (depth of surface soil samples) to -115 cm are designated as minus one meter (-
Im) samples while those taken from the interval -115cm to -215 cm are referred to as minus two meter (-2m) samples. Due to the existence of numerous sub-surface utility support structures (piping, cable duct-boxes, sewer lines, etc.) as well as over dimension fill and debris existing undetected below grade level, sample refusal was not an uncommon occurrence. No incident of refusal culminated in the inability to acquire a two meter sample within a one meter radius (the relocation allowance criteria) of the surface and one meter sample locations. Each soil sample taken was 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 8 FSS Summary Report F8100022
Table 1. Survey Unit Design Parameters Survey Design Parameter [ Value Comment Survey Area: F810 Tank Farm - N.W. Quadrant Subsurface Soil Survey Unit: 0022 Open Land Area Class: 1 LTP Table 5-4 SU Area (m2): 1618 IAW F8100021 Evaluator: D.A.Tallman DCGL for Cs-137 surrogate (pCi/g): 52.6 DCGL for Co-60 (pCi/g): 12.6
'1.2 Area Factor: Class 1 - IAW F8100021 Design DCGLemc (pCi/g): 62.97 Class 1 - IAW F8100021 LBGR (pCi/g): 26.3 50% DCGL for Cs-137 surrogate (pci/g):
Design Sigma (pCi/g): 10.7 DTBD-06-001, Table 5-4B lAW F8100021 Type I Error: 0.05 Type II Error: 0.05 Sample Area (m2): 107.9 Class 1 Total Area Scanned (m2): 0 SubSurface Soil Scan Coverage (%): 0% SubSurface Soil - NA 1.645 ZI-: 1.645 Sign P: 0.99379 Calculated Relative Shift: 2.5 Relative Shift Used: 2.5 Uses 3.0 if Rel Shift >3 N-Value: 12 Design N-Value + 20%: 15 NUREG-1575 Table 5-5 Grid Spacing L: 10 Reduced to 10 meters to meet minimum "N" lAW F8100021 Page 3 of 8 FSS Summary Report F8100022
Survey Results:
A total of 34 direct measurements were made in1F8100022. The results are shown in Table 2-1. Statistical data including the mean, median, and standard deviation are shown in Table 2-2. All of the direct measurements were less than Unity. Soil samples were counted to the MDCs shown in Table 2-1 of Attachment 2.
Page 4 of 8 FSS Summary Report F8100022
Table 2-1. Direct Measurement Results (all activity values in pCi/g)
Sample ID MDA Activity Uncertainty Unity ValueValue Activity MDA Uncertainty Unity Unity Total F8100022S001ISS 4.38E-02 <4.38E-02 0.0008 4.37E-02 <4.37E-02 0.0035 0.0043 F8100022S0021SS 6.08E-02 1.09E-01 4.55E-02 0.0021 6.36E-02 <6.36E-02 0.005 0.0071 F8100022S0031SS 6.22E-02 <6.22E-02 4.27E-02 0.0012 7.76E-02 <7.76E-02 0.0062 0.0073 F8100022S0041SS 4.87E-02 <4.87E-02 0.0009 2.07E-02 <2.07E-02 0.0016 0.0026 F8100022SO051SS 4.87E-02 <4.87E-02 0.0009 5.50E-02 <5.50E-02 0.0044 0.0053 F8100022S0061SS 5.80E-02 <5.80E-02 0.0011 5.41E-02 <5.4 1E-02 0.0043 0.0054 F8100022S0071SS 6.13E-02 1.92E-01 5.46E-02 0:0036 4.89E-02 <4.89E-02 0.0039 0.0075 F8100022S0081SS 5.8 1E-02 <5.8.1E-02 0.0011 5.43E-02 <5.43E-02 0.0043 0.0054 F8100022S0091SS 8.28E-02 7.1OE-01 9.78E-02 0.0135 7.25E-02 <7.25E-02 0.0058 0.0193 F8100022SO10ISS 5.64E-02 <5.64E-02 0.0011 4.60E-02 <4.60E-02 0.0037 0.0047 F8100022SO11ISS 3.88E-02 <3.88E-02 0.0007 1.68E-02 <1.68E-02 0.0013 0.0021 F8100022S0121SS 4.74E-02 <4.74E-02 0.0009 3.80E-02 <3.80E-02 0.003 0.0039 F8100022S0131SS 5.60E-02 LO1E-01 4.46E-02 0.0019 7.94E-02 <7.94E-02 0.0063 0.0082 F8100022S0141SS 1.28E-01 3.62E01 5.5.3E-01 0.6879 4.34E-02 3.65E-01 4.98E-02 0.029 0.7169 F8100022S0151SS 4.25E-02 <4.25E-02 0.0008 4.33E-02 <4.33E-02 0.0034 0.0042 F8100022S016ISS 9.04E-02 <9.04E-02 0.0017 6.19E-02 <6.19E-02 0.0049 0.0066 F8100022S0171SS 5.51E-02 <5.51E-02 0.001 4.36E-02 <4.36E-02 0.0035 0.0045 F8100022S0012SS 4.05E-02 <4.05E-02 0.0008 4.78E-02 <4.78E-02 0.0038 0.0046 F8100022S0022SS 3.96E-02 <3.96E-02 0.0008 3.45E-02 <3.45E-02 0.0027 0.0035 F8100022S0032SS 7.50E-02 <7.50E-02 0.0014 6.72E-02 <6.72E-02 0.0053 0.0068 F8100022S0042SS 4.11E-02 <4.1 1E-02 0.0008 4.11 E-02 <4.1 1E-02 0.0033 0.004 F8100022S0052SS 4.22E-02 <4.22E-02 0.0008 5.51E-02 <5.51E-02 0.0044 0.0052 F8100022S0062SS 5.29E-02 <5.29E-02 0.001 5.86E-02 <5.86E-02 0.0047 0.0057 F8100022S0072SS 4.88E-02 <4.88E-02 0.0009 3.97E-02 <3.97E-02 0.0032 0.0041 F8100022S0082SS 5.75E-02 <5.75E-02 0.0011 4.21E-02 <4.21E-02 0.0033 0.0044 F8100022S0092SS 4.11E-02 <4.11E-02 0.0008 4.43E-02 <4.43E-02 0.0035 0.0043 F8100022S0102SS 4.77E-02 <4.77E-02 0.0009 4.87E-02 <4.87E-02 .0.0039 0.0048 F8100022S0112SS 4.39E-02 <4.39E-02 0.0008 5.81E-02 <5.81E-02 0.0046 0.0054 F8100022S0122SS 4.32E-02 <4.32E-02 0.0008 5.37E-02 <5.37E-02 0.0043 0.0051 F8100022S0132SS 4.96E-02 <4.96E-02 0.0009 4.47E-02 <4.47E-02 0.0035 0.0045 F8100022S0142SS 5.85E-02 9.93E-01 9.09E-02 0.0189 4.84E-02 <4.84E-02 0.0038 0.0227 F8100022S0152SS 2.59E-02 <2.59E-02 0.0005 2.07E-02 <2.07E-02 0.0016 0.0021 F8100022S0162SS 3.95E-02 <3.95E-02 0.0008 3.23E-02 <3.23E-02 0.0026 0.0033 F8100022S0172SS 4.30E-02 <4.30E-02 0.0008 4.39E-02 <4.39E-02 0.0035 0.0043 Page 5 of 8 FSS Summary Report F8100022
Table 2-2. Direct Measurements Results Summary Cs137 Co60 y,
- Activity Activity Cs137 Unity Co60 Unity Unity Total (pCi/) .....(pCi..)
DCGLw 52.6 12.6 i .
Mean 1.17E00 5.78E-02 0.0222 0.0046 0.0268 Median 4.88E-02 4.81E-02 0.0009 0.0038 0.0047 Standard Dvation 6.19E00 5.63E-02 0.1177 0.0045 0.122 Deviation Cs137 Activity Range (pCi/g) 2.59E-02 to 3.62E01 Co60 Activity Range (pCi/g) 1.68E-02 to 3.65E-01 Cs137 Unity Range 0.0005 to 0.6879 Co60 Unity Range 0.0013 to 0.029 Total Unity Range 0.0021 to 0.7169 Sample Count 34 Page 6 of 8 FSS Summary Report F8100022
Survey Unit Data Assessment:
The survey design required 34 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.
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N): 34 17 at one meter, 17 at two meters Median (Unity): 0.005 Mean (Unity): 0.027 Direct Measurement Std Deviation (unity): 0.122 Maximum (Unity): 0.717 Sign Test Final N Value: 34 S+ Value: 34 Critical Value: 22 Sufficient Samples Collected: Yes Maximum Value < Unitized DCGL: Yes Median Value < Unitized DCGL: Yes Mean Value < Unitized DCGL: Yes Maximum Value < DCGLemc (Unity): Yes Class 1 Standard Deviation <= Sigma: Yes Pass the Sign Test? Yes Reject the Null Hypothesis? Yes Does the Survey Unit Pass All Criteria? Yes Page 7 of 8 FSS Summary Report F8100022
Survey Unit Investigations and Results:
No investigations were required for direct measurements therefore, 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 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. No potential areas of elevated activity were detected.
==
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 as a subsurface soil survey, scan coverage is not applicable. All of the direct measurements were less than Unity. 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 F8100022 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F8100022
Attachment 1 Maps
,January 8, 2009 Survey Unit F8100022
00
>) Zone 3 SCALE METERS 0 5 10 TANK FARM - ZONE 2 Stjr[:ee Area E.krates S oi 1539 ml GENERAL ARRANGEMENT PLAN VIEW K",
Asphal 79 mn I-) SMUT SURFACE AREA ESTIMATE Ioial 1618n , ff L U~L DTRICT F8100021-Mi
. SHEET 1 of!
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TANK FARM - ZONE 2 0,
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SCALEME~tPfS SSMUG3 SOIL SAMPLE RANDOM START LOCATION DI-.TRIU!
UTILITY F8100021-M2 SHEET 1 of2 5 iS l? 18 ii
OP 00 0 TANK FARM - ZONE 2 0k)
SOIL SAMPLE t'J SCALE MEIERS SAC PAV-EN O MUINIIPAiL LOCATIONS 0 5 10 "UTILITY D-1STR;:CT F8100021-M2 SHEET 2 OF 2
Attachment 2 Instrumentation January 8, 2009 Survey Unit F8100022
Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model MDC No.No.
HPGe N/A 05069128 Soil -0.1280 pCi/g Cs-137 Soil - 0.0794 pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value HPGe Investigation Criteria 63.0 pCi/g Cs137 surr.
52.6 Cs-137 12.6 Co-60 All DCGLEMC 63.0 pCi/g Cs 137 surr.
Page 2 of 2 Att. 2 Instrumentation F8100022
Attachment 3 Investigation January 8, 2009 Survey Unit F8100022 (none required)
Attachment 4 Data Assessment January 8, 2009
.Survey Unit F8100022
F8100022 Quantile Plot 0.600 0.400 7 El -~0.800 -** -
-~ g 0.200
> 0.000 -0.005
-0.200
-0.400 -
-0.600 0 20 40 60 80 100 Percentile Unitized Total Value - Median - - 75th Percentile -... 50th Percentile 0)
0 F81 00022 Scatter Plot 0,800 0.600 -
0.400- 0.393 E3 0.200 -
N
-"-- - - - - -- ' - - - - ----- '-' -. -----"- 8 - "---
0.027 0.000 CDJ
-0.200
-0.339
-0,400 02UttO I- T- - T_ T_ V_ T- T- It- Vn. m c- N N N N N N N N N N Measurement Locations I o Unitized Total Value - -Average - - - "+3SIDev" - - -- 3SWDer'I
-Il 00 C)
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0 F8100022 Frequency Plot 34-32-30*
~26-
~22-
~20-
~18-5 16 -
~14-
~12-
~10 -
Bins - Upper End Value (Unitized Total) 00