ML081620210
| ML081620210 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/21/2008 |
| From: | Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| F8991091 | |
| Download: ML081620210 (22) | |
Text
Rancho Seco Final Status Survey Summary Report March 31, 2008 RHUT Trench Survey Unit F8991091 CrrQ Prepared By&
Date:_____
Reviewed Approved
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Engineer 7
Date:
2v 2-0 g Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8991091, RHUT Trench Survey Unit
Description:
Operating History: The RHUT pipe collected contaminated water as part of the radioactive effluent system and transported it to. the retention basins for discharge.
Operating records and the HSA document occurrences of radioactive contamination associated with this system piping.
Site Characterization: Direct measurements were made of the interior surfaces of the system piping which confirmed the presence of plant-derived radionuclides. Direct.
measurements of the interior showed a mean gross activity level of 2590 dpm/100 cm2 and a maximum value of 3158 dpm/100 cm2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the pipe was determined to be a Class 1 system and the trench was a Class 2.
HSA Events: HSA Report pg. 63.
Survey Unit Design Information:
Approximately 1200 feet of the contaminated RHUT pipe was dug up and removed as' part of site remediation. This survey covers the open trench following pipe removal in addition to the "as left" surface of the back filled trench in those areas that were subsequently paved over (see maps). The portions of the back filled trench that were not repaved are surveyed as part of the appropriate land areas.
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 1988 m2 were scanned for approximately 129% 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 is listed in Tables 2-1 and 2-2 in Attachment 2.
Page 2 of 9 FSS Summary Report F8991091
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area:
F899 RHUT Trench Survey Unit:
1091 Open Land Area Class:
2 LTP Table 5-4 SU Area (m2):
1544 Evaluator:
Gary Frank DCGL for Cs-137 surrogate (pCi/g):
52.6 DCGL for Co-60 (pCi/g):
12.6 Area Factor:
N/A Class 2 Design DCGLemc (pCi/g):
N/A Class 2 LBGR (pCi/g):
25.6 Adjusted Design Sigma (pCi/g):
9.83 DTBD-06-001, Table 5-4A or B Type I Error:
0.05 Type II Error:
0.05 Sample Area (m2):
102.9 Class 2 Total Area Scanned (m2):
1988 Scan Coverage (%):
128.8%
Class 2 ZI. :1.645 Zl-O :1.645 Sign P:
0.99379 Calculated Relative Shift:
2.7 Relative Shift Used:
2.7 Uses 3.0 if Rel Shift >3 N-Value:
12 Design N-Value + 20%:
15 NUREG-1575 Table 5-5 Grid Spacing L:
10.1 Class.2 Page 3 of 9 FSS Summary Report F8991091
Survey Results:
A total of 53 direct measurements (soil samples) were made in F8991091. 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. None of the scan measurements indicated areas of elevated activity. Soil samples were counted to the MDCs shown in Table 2-1 of Attachment 2.
Additional scan measurements (93) were performed with 2350-1 and 44-10 for discrete particle detection in the trench and spoils pile with results below the investigation level of 9280 cpm with the exception of areas with sediment from the pipe. During the removal of the pipe, sediment fell out of the pipe into the trench. Thermaterial was removed and the trench sampled to ensure the release criteria were met.
Page 4 of 9 FSS Summary Report F8991091
Table 2-1. Direct Measurement Results (all activity values in pCi/g)
Cs 137 Co6O Sample ID MDA Activity Uncertainty Unity MDA Activity Uncertainty Unity Unity Value Value Total F8991091S0041SS 6.22E-02 3.88E-01 6.62E-02 0.0074 5.95E-02
<5.95E-02 0.0047 0.0121 F8991091S0042SS 8.52E-02 1.63E00 1.30E-01 0.031 5.45E-02 3.94E-01 5.64E-02 0.0313 0.0623 F8991091S0043SS 5.46E-02
<5.46E-02 0.001 6.55E-02
<6.55E-02 0.0052 0.0062 F8991091S0044SS 3.99E-02 3.28E-01 5.33E-02 0.0062 6.76E-02
<6.76E-02 0.0054 0.0116 F8991091S0045SS 4.55E-02 6.93E-02 3.34E-02 0.0013 5.45E-02
<5.45E-02 0.0043 0.0056 F8991091S0050SS 4.02E-02 1.17E-01 3.57E-02 0.0022 5.13E-02
<5.13E-02 0.0041 0.0063 F8991091S0053SS 6.20E-02 1.02E-01 4.64E-02 0.0019 7.02E-02
<7.02E-02 0.0056 0.0075 F8991091S0054SS 5.95E-02 8.40E-02 4.24E-02 0.0016 6.62E-02
<6.62E-02 0.0053 0.0069 F8991091S0057SS 5.35E-02
<5.35E-02 0.001 3.67E-02
<3.67E-02 0.0029 0.0039 F8991091S0058SS 3.43E-02 2.58E-01 4.60E-02 0.0049 6.55E-02
<6.55E-02 0.0052 0.0101 F8991091S0059SS 5.29E-02 2.53E-01 5.33E-02 0.0048 5.33E-02
<5.33E-02 0.0042 0.009 F8991091S0060SS 4.09E-02
<4.09E-02 0.0008 4.29E-02
<4.29E-02 0.0034 0.0042 F8991091S0061SS 4.85E-02 1.76E-01 4.45E-02 0.0033 5.07E-02
<5.07E-02 0.004 0.0074 F8991091S0063SS 5.75E-02
<5.75E-02 0.0011 4.13E-02
<4.13E-02 0.0033 0.0044 F8991091S0064SS 3.83E-02 9.50E-02 3.26E-02 0.0018 4.37E-02
<4.37E-02 0.0035 0.0053 F8991091S0065SS 6.59E-02
<6.59E-02 0.0013 5.09E-02
<5.09E-02 0.004 0.0053 F8991091S0066SS 6.13E-02 4.96E-01 7.24E-02 0.0094 5.63E-02
<5.63E-02 2.84E-02 0.0045 0.0139 F8991091S0067SS 5.05E-02
<5.05E-02 0.001 5.36E-02
<5.36E-02 0.0043 0.0052 F8991091S0068SS 5.90E-02 1.88E-01 4.96E-02 0.0036 6.03E-02
<6.03E-02 0.0048 0.0084 F8991091S0069SS 4.30E-02
<4.30E-02 0.0008 3.97E-02
<3.97E-02 0.0032 0.004 F8991091S0070SS 5.57E-02 3.06E-01 5.75E-02 0.0058 6.02E-02
<6.02E-02 0.0048 0.0106 F8991091S0071SS 5.43E-02 2.52E-01 5.33E-02 0.0048 5.99E-02
<5.99E-02 0.0048 0.0095 F8991091S0072SS 5.07E-02
<5.07E-02 0.001 4.1OE-02
<4.1OE-02 0.0033 0.0042 F8991091S0073SS 5.79E-02 1.76E-01 4.94E-02 0.0033 6.89E-02
<6.89E-02 0.0055 0.0088 F8991091S0074SS 4.72E-02 2.04E-01 4.73E-02 0.0039 6.02E-02
<6.02E-02 0.0048 0.0087 F8991091S0075SS 6.67E-02
<6.67E-02 0.0013 4.94E-02
<4.94E-02 0.0039 0.0052 F8991091S0076SS 5.02E-02
<5.02E-02 0.001 5.46E-02
<5.46E-02 0.0043 0.0053 F8991091SO077SS 6.57E-02
<6.57E-02 0.0012 4.03E-02
<4.03E-02 0.0032 0.0044 F8991091S0078SS 6.09E-02 1.63E-01 4.93E-02 0.0031 4.29E-02
<4.29E-02 0.0034 0.0065 F8991091S0079SS 5.02E-02 7.32E-02 3.62E-02 0.0014 5.53E-02
<5.53E-02 0.0044 0.0058 F8991091S0080SS 5.61E-02
<5.61E-02 0.0011 4.60E-02
<4.60E-02 0.0037 0.0047 Page 5 of 9 FSS Summary Report F8991091
F8991091S0081SS 5.57E-02
<5.57E-02 0.0011 4.41E-02
<4.41E-02 0.0035 0.0046 F8991091S0082SS 4.74E-02
<4.74E-02 0.0009 5.06E-02
<5.06E-02 0.004 0.0049 F8991091S0083SS 4.69E-02
<4.69E-02 0.0009 4.34E-02
<4.34E-02 0.0034 0.0043 F8991091S0084SS 5.47E-02 6.75E-01
' 8.26E-02 0.0128 1.06E-01
<1.06E-01 0.0084 0.0212 F8991091S0085SS 5.55E-02 2.46E-01 5.51E-02 0.0047 7.49E-02
<7.49E-02 0.0059 0.0106 F8991091S0086SS 4.73E-02
<4.73E-02 0.0009 4.04E-02
<4.04E-02 0.0032 0.0041 F8991091S0087SS 4.76E-02
<4.76E-02 0.0009 6.07E-02
<6.07E-02 0.0048 0.0057 F8991091S0089SS 5.66E-02 3.89E-01 6.54E-02 0.0074 6.79E-02
<6.79E-02 0.0054 0.0128 F8991091S0090SS 5.65E-02
<5.65E-02 0.0011 5.12E-02
<5.12E-02 0.0041
-0.0051 F8991091S0091SS 5.93E-02
<5.93E-02 0.0011 4.11E-02
<4.11E-02 0.0033 0.0044 F8991091S0092SS 3.45E-02 4.03E-02 2.47E-02 0.0008 5.09E-02
<5.09E-02 0.004 0.0048 F8991091S0093SS 6.06E-02
<6.06E-02 0.0012 4.89E-02
<4.89E-02 0.0039 0.005 F8991091S0094SS 7.72E-02
<7.72E-02 0.0015 5.68E-02
<5.68E-02 0.0045 0.006 F8991091S0095SS 6.11E-02
<6.11E-02 0.0012 4.80E-02
<4.80E-02 0.0038 0.005 F8991091S0096SS 5.68E-02 2.74E-01 5.36E-02 0.0052 6.05E-02
<6.05E-02 0.0048 0.01 F8991091S0097SS 3.90E-02
<3.90E-02 0.0007 4.64E-02
<4.64E-02 0.0037 0.0044 F8991091S0098SS 4.55E-02 1.63E-01 4.21E-02 0.0031 5.09E-02
<5.09E-02 0.004 0.0071 F8991091S0099SS 5.89E-02 6.53E-02 3.96E-02 0.0012 5.75E-02
<5.75E-02 0.0046 0.0058 F8991091S0100SS 6.30E-02 3.48E-01 6.33E-02 0.0066 7.43E-02
<7.43E-02
_0.0059 0.0125 F8991091S0101SS 6.30E-02 3.48E-01 6.33E-02 0.0066 7.43E-02
<7.43E-02 0.0059 0.0125 F8991091S0102SS 6.88E-02
<6.88E-02 0.0013 5.56E-02
<5.56E-02 0.0044 0.0057 F8991091S0103SS 5.58E-02 2.34E-01 5.15E-02 0.0044 5.38E-02
<5.38E-02 0.0043 0.0087 Page 6 of 9 FSS Summary Report F8991091
Table 2-2. Direct Measurements. Results Summary
~~<K~
Cs137 C~o6O S.
Activity Activity Cs137 Unity Co60 Unity Unity Total
- m*.............. *,,*.
(pCi/g) pCi/!
DCGLw 52.6 12.6 7:
Mean 1.79E-01 6.15E-02 0.0034 0.0049.
0.0083 Median 7.32E-02 5.38E-02 0.0014 0.0043 0.0058 Standard Deviation 2.45E-01 4.81E-02 0.0047 0.0038 0.0083 Cs137 Activity Range (pCi/g) 3.90E-02 to 1.63E00 Co60 Activity Range (pCi/g) 3.67E-02 to 3.94E-01 Cs137 Unity Range 0.0007 to 0.031 Co60 Unity Range 0.0029 to 0.0313 Total Unity Range 0.0039 to 0.0623 Sample Count 53 Survey Unit Data Assessment:
The survey design required 53 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 7 of 9 FSS Summary Report F8991091
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N):
53 Median (Unity):
0.006 Mean (Unity):
0.008 Direct Measurement Std Deviation (Unity):
0.008 Maximum (Unity):
0.062 Sign Test Final N Value:
53 S+ Value:
53 Critical Value:
32 Sufficient Samples Collected:
Yes Maximum Value < Unitized DCGL:
Yes Median Value < Unitized DCGL:
Yes Mean Value < Unitized DCGL:
Yes Maximum Value < DCGLemc (Unity):
N/A Class 2 Standard Deviation <= Sigma:
Yes Pass the Sign Test?
Yes Reject the Null Hypothesis?
Yes Does the Survey Unit Pass All Criteria?
Yes Page 8 of 9 FSS Summary Report F8991091
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 the ALARA criterion has been met.
Changes in Initial Survey Unit Assumptions:
The survey unit was designed as a Class 2 land survey and the sample results are consistent with that classification. The variability of the survey results was less than the cha racterization 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 2 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 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 F8991091 meets the release criteria of 10CFR20.1402.
Page 9 of 9 FSS Summary Report F8991091 Maps March 31, 2008 Survey Unit F8991091
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Surface gamma scans start at the northern most point (01 GS) for a total of 32 surface scans ending at the Retention Basin Mixing Box.
"3L 6812753E 1888114.OON 6812831E 1888126.00N 1888297.40N 1888258.03N 1888218.66N 1888179.29N 6813423.97E 1888162.59N O 10 20 0
SCALE METERS(9 RHUT TRENCH SURFACE ISOCS SCANS F8991 091 -M1 SHT 1 OF R
AREA TO BE SURVEYED
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L =----j i Gamma Direct background measurements are performed on odd numbered scan locations 07GS 08GS 09GS 28GS 26GS lOGS O 10
- 20 30 SCALE-METERS N9 00 RHUT TRENCH SURFACE ISOCS SCANS F8991091 -M2 SHT I OF R
AREA TO BE SURVEYED
RHUT Trench North Soil Sample 11D [----
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.Soil samples in red PR95SS PR52S required remediation PRMUSE those in green are satisfactory PR97SS -
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PR41 PR4ý Samples with PR prefix PR47SS indicate post remediation PR46SS 49GS 4
55GS 51GS 57GS 58s 57SS 9ISSIQC F8991091-M3 Page 4 of 6 Att. 1 Maps F8991091
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SCALE METERS(a 00 RHUT TRENCH ROAD REPAVING GEN ARRMT F8991091 -M5 Rqq lInq SHT 1 OF 2 RC RAYM Instrumentation March 31, 2008 Survey Unit F8991 091
Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model No.
MDC No.
HPGe N/A 05047773 Soil - 0.059 pCi/g Cs-137 HPGe N/A 05069128 Soil - 0.389 pCi/g Cs-137 Soil - 0.296 pCi/g Cs-137 ISOCS N/A 2983947 Soil - 0.226 pCi/g Co-60 I
I Asphalt - 0.314 pCi/g Cs-137 M2350-1 44-10 171995 Scan 5.2 pCi/g Cs-137 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value Soil - 26.3 pCi/g Cs-137 ISOCS Investigation Criteria - Scan Soil - 6.3 pCi/g Co-60 Asphalt - 26.3 pCi/g Cs-137 Investigation Criteria-9280 cpm-NaI Scan All DCGLw 52.6 Cs-137 12.6 Co-60 All DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8991091 Investigation March 31, 2008 Survey Unit F8991091 (none required)
Data Assessment March 31, 2008 Survey Unit F8991 091
t*d 4ý1 F8991091 Quantile Plot
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