ML081610115
| ML081610115 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/18/2008 |
| From: | Donna Anderson Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| F1000004 | |
| Download: ML081610115 (23) | |
Text
Rancho Seco Final Status Survey Summary Report March 18, 2008 Plant Effluent Water Course (SU4)
Survey Unit F1000004 Prepared By:_
Reviewed By:
FSS J-r Date:
311/'1 2LO8 Date: J,,/i i Lead FSS Engineer Approved By:
Date:
-0
-)
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F 1000004, Plant Effluent Water Course (SU4)
Survey Unit
Description:
Operating History: This area was the release point for liquid effluents released from the plant. The area was impacted by both planned and unplanned liquid releases. Effluents were monitored under the operating RETS/REMP program. Operating records and the HSA document the release of radioactivity in this survey area. The HSA recorded multiple unplanned release events.
Site Characterization: Soil and sediment samples were collected and analyzed for the presence of plant-derived radionuclides. Cs-137 was the predominant nuclide with a mean activity level of 9.2 pCi/g and a maximum value of 48.2 pCi/g. The Characterization data were found to be conservative when compared to the historical information found in the reports referenced in the PDP. During the final status survey of F 1000001 (Plant Effluent Water Course, SU 1), ISOCS gamma measurements identified average activity exceeding the investigation level for a Class 2 soil survey. An investigation was performed and soil activity exceeding the DCGL of 52.6 pCi/g Cs-137 was identified. The 11-meter by 18-meter area was subsequently remediated and reclassified as a Class I land area, based on the classification procedure (DSIP-0020). As a result of the reclassification, a new survey package was initiated as F 1000004.
HSA Events: ODR-740017, 740052, 750046, 760079, 810192, 810193, 810209, 83008, 830023, 830248, 840117, 84Q118, 840225, 840223, 850299, 850112, 860555, 870764, 870905.
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 198 m2 were scanned for 100% 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 are listed in Tables 2-1 and 2-2 in Attachment 2.
Page 2 of 8 FSS Summary Report F 1000.004
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area:
F1O0 Plant Effluent Water Course (SU4)
Survey Unit:
0004 Open Land Area Class:
1 LTP Table 5-4 SU Area (m2):
198 F8000071 Evaluator:
D. Anderson DCGL for Cs-137 surrogate (pCi/g):
52.6 DCGL for Co-60 (pCi/g):
12.6 Area Factor:
2.1 Class 1 Design DCGLemc (pCi/g):
108 Class 1 LBGR (pCi/g):
25.8 Adjusted Design Sigma (pci/g):
9.03 DTBD-06-001, Table 5-4A or B Type I Error:
0.05 Type II Error:
0.05 Sample Area (M2):
13.2 Class I Total Area Scanned (m2):
198 Scan Coverage (%):
100%
Class 1 ZI.a :
1.645 ZJ-P :
1.645 Sign P:
0.99379 Calculated Relative Shift:
2.9 Relative Shift Used:
2.9 Uses 3.0 if Rel Shift >3 N-Value:
12 Design N-Value + 20%:
15 NUREG-1575 Table 5-5 Grid Spacing L:
3.6 Class I Page 3 of 8 FSS Summary Report F1000004
Survey Results:
A total of 15 direct measurements were made in F 1000004. The results are shown in Table 2-I1. 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.
Page 4 of 8 Page 4 of 8 FSS Summary ReportF1004 F1000004
Table 2-1. Direct Measurement Results (all activity values in pCi/g)
Cs 137 Co6O Unity Unity Unity Sample ID MDA Activity Uncertainty MDA Activity Uncertaintyt Value MD ciiy Ucrany Value Total F1000004SOOOISS 1.29E-01 1.49E01 4.12E-01 0.2842 1.02E-0I
<1.02E-01 0.0081 0.2923 FI000004SO002SS 9.57E-02 4.58E00 2.28E-01 0.087 9.10E-02
<9.10E-02 0.0072 0.0942 F1000004SO003SS 1.14E-01 1.67E01 4.26E-01 0.3169 5.00E-02 1.16E-01 4.02E-02 0.0092 0.3261 F1000004S0004SS 8.1OE-02 6.54E00 2.61E-01 0.1242 9.05E-02
<9.05E-02 0.0072 0.1314 F1000004S0005SS 1.08E-01 9.47E00 3.02E-01 0.18 6.25E-02 8.04E-02 3.33E-02 0.0064 0.1864 F1000004SO006SS 1.75E-01 2.76E01 5.78E-01 0.5241 6.30E-02 3.08E-01 5.64E-02 0.0244 0.5486 F1000004SO007SS 6.96E-02 1.22E00 1.1OE-01 0.0231 6.32E-02
<6.32E-02 0.005 0.0281 F1000004SO008SS 5.67E-02 1.26E00 1.1OE-01 0.0239 6.12E-02
<6.12E-02 0.0049 0.0287 F1000004SO009SS 6.72E-02 1.77E00 1.28E-01 0.0337 6.69E-02
<6.69E-02 0.0053 0.039 F1000004SOOlOSS 7.60E-02 3.60E00 1.89E-01 0.0684 7.38E-02
<7.38E-02 0.0059 0.0742 F1000004SO011SS 1.26E-01 1.53E01 4.13E-01 0.2917 4.83E-02 1.52E-01 4.05E-02 0.0121 0.3038 F1000004S0012SS 1.02E-01 5.16E00 2.37E-01 0.0981 8.83E-02
<8.83E-02 0.007 0.1051 F1000004SO013SS 8.79E-02 3.08E00 1.76E-01 0.0585 8.17E-02
<8.17E-02 0.0065 0.065 FI000004S0014SS 1.32E-01 1.66E00 1.72E 0.0315 9.93E-02
<9.93E-02 0.0079 0.0394 F1000004S0015SS 6.6 1E-02 1.12E00 1.06E-01 0.0213 6.80E-02
<6.80E-02 0.0054 0.0267 Page 5 of 8 FSS Summary Report F1000004
Table 2-2. Direct Measurements Results Summary Cs137 1 Co6O Activity Activity Cs137 Unity Co60 Unity Unity Total
- ,(pC Ig)
I (pG j g)
________i_
_Ci/_
DCGLw 52.6 12.6 "t
Mean 7.60E00 1.03E-01 0.1444 0.0082 0.1526 Median 4.58E00 8.83E-02 0.087 0.007 0.0942 Standard Dvan 7.76E00 6.14E-02 0.1476 0.0049 0.1518 Deviation Cs137 Activity Range (pCi/g) 1.12E00 to 2.76E01 Co60 Activity Range (pCi/g) 6.12E-02 to 3.08E-01 Cs137 Unity Range 0.0213 to 0.5241 Co60 Unity Range 0.0049 to 0.0244 Total Unity Range 0.0267 to 0.5486 Sample Count 15 Survey Unit Data Assessment:
The survey design required 15 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*6 of 8 FSS Summary Report F1000004
Table 3. Data Assessment Results Survey Results Parameter Value Comment
.Actual Direct Measurements (N):
15 Median (Unity):
0.094 Mean (Unity):
0.153 Direct Measurement Std Deviation (Unity):
0.152 Maximum (Unity):
0.549 Sign Test Final N Value:
15 S+ Value:
15 Critical Value:
11 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 F1000004
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 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. 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 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 F 1000004 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F1000004 Maps March 18, 2008 Survey Unit F1000004
Page 2 of 8 Att. 1 Maps F1000004
-o 0
00 CA, 0:)
0 0
0 0
Map F 1000004-2, Plant Effluent Water Course (SU4)
Approximate Area to be Remediated
-o 0
Go or 00 Map F1000004-3, Plant Effluent Water Course (SU4), Appearance of area following remediation efforts
(DI 00 00
-e Coordinates:
Map F1000004-4, Plant Effluent Water Course (SU4)
Area Estimate: 198 sq. meters 1887765.8 6812013.0 N
Distanc in Meter Q)
L/
(Jo CI) 0 00 Random Start Location 4.2 m from West Boundary 4.6 m from North Boundary 0) 0)
I..0 0~
0 0
5 I0 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 Ir1 C) 0 0.5 1.0 15 2.0 Distance in Meters
/
Map F1000004-5, Plant Effluent Water Course (SU4)
Random Start Location
Map F1000004-6, Plant Effluent Water Course (SU4)
Soil Sampte (Direct Measurement) Locations
/
F1000004SOOO1 SS to F1000004SO015SS CD
-3.76 meter grid 00 0
00
/7 6
C)-
Distance in Meters
0 00 U)
Map F1 000004-7, Plant Effluent WaterCourse (SU4)
ISOCS Gamma Scan Measurements F1000004S0001 GS to F1000004S0028GS 12.57 sq. meter field of view a) a)
C-)
too C,)V to*o 0
0.5 1.0 1-5 2.0 Distance in Meters 4 0.? /)?
7 7-,
47,
/
'S C) 0 Instrumentation March 18, 2008 Survey Unit F1000004
Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model No.MDC No.
HPGe N/A 05069128 Soil -1.75E-01 pCi/g Cs-137 Soil - 1.02E-01 pCi/g Co-60 Soil - 2.74E-01 pCi/g Cs-137 Soil - 2.25E-01 pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value ISOCS Investigation Criteria - Scan Soil-50 pCi/g Cs-137 Soil - 10 pCi/g Co-60 All DCGLw 52.6 Cs-137 12.6 Co-60 All DCGLEMC 108 pCi/g Cs-137 Page 2 of 2 Att. 2 Instrumentation F1000004 Investigation March 18, 2008 Survey Unit F1000004 (none required)
Data Assessment March 18, 2008 Survey Unit F1000004
CD 0*
F1 000004 Qua ntile Plot 0.600 0.500 0.400 N
4-. 0.300 0.200 0.100 0.000 0.094 0
20 40 60 80 100 Percentile Unitized Total Value -
Median -
- - 75th Percentile - - - - 50th Percentile
CD U)
Co CD Co CD 0r 01 Fl 000004 Scatter Plot V
C 04800 0.600 0.400 0.200 0.000
-0.200
-0.400
.t
--6 0
0 o0 0
0 6 '..
O.
2.153
.0.303 Measurement Locations o
Unitized Total Value --
Average - - - "+3StDev" -
-3StDev" I
CD cIQ (D~
0 C-)
C.)
ct*
Cl)
(t*
F1000004 Frequency Plot 10 9
0 1)
Cr U)
LL 0
(I)
..Q0 8
7 6
5 4
3 2
1 0
A, Q).
Bins - Upper End Value (Unitized Total)