ML082620107
| ML082620107 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 02/28/2008 |
| From: | Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-064 | |
| Download: ML082620107 (40) | |
Text
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Rancho Seco Final Status Survey Summary Report February 28, 2008 Retention Basin Out Buildings Survey Unit F8480019 Prepared By.___*________ _ Date:_______
FSS nr Reviewed By:_______________ Date:
Leao/FSS Engineer Approved By: Date: 7- 1' -
Dismantlement Stpperintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8480019, Retention Basin Out Buildings Survey Unit
Description:
Operating History: This area is located at the southwest comer of the site. The area surrounds the structures that were used for containment and final treatment of liquid effluents prior to their release from the site. Contaminated resin was reported to have been found in the basins. Operating records and the HSA document occurrences of radioactive material with the potential for a release of radioactivity associated with this survey area. Records confirmed the presence of radioactive material within the area and basin sediment/soil contamination levels up to -290 pCi/g. In addition, soil contamination levels up to -5 pCi/g prior to some decontamination activities.
Site Characterization: Soil samples were collected and showed Cs-137 at mean activity levels of 0.086 pCi/g and a maximum activity of 0.196 pCi/g. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the soil area around the asphalt was determined to be Class 3.
HSA Events: LER-8812.
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 75 m2 were scanned for approximately 28%
coverage. Samples of removable contamination were collected at each direct measurement location. 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 F8480019
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F848 Retention Basin Out Buildings Survey Unit: 0019 Structure Surface Class: .3 LTP Table 5-4 SU Area (m): 272 Evaluator: Gary Frank DCGL (dpm/100 cm 2): 43000 Gross Activity DCGL Area Factor: N/A Class 3 Design DCGLemc N/A Class 3 (dpm/100 cm 2):
LBGR (dpm/100 cm 2): 21500 Default = 50% DCGL Design Sigma (dpm/100 cm 2): 431 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): N/A Class 3 Scan Area (m2): 75 Scan Coverage (%): 28% Class 3 Zl., :
1.645 ZI-P : 1.645 Sign P: 0.99865 Calculated Relative Shift: 49.8 Relative Shift Used: 3 Uses 3.0 if Relative Shift is
>3 N-Value: 11 Design N-Value + 20%: 14 NUREG-1575 Table 5-5 Design Min Samples N: 14 Class 3 Grid Spacing L: N/A Class 3 Page 3 of 8 FSS Summary Report F8480019
Survey Results:
A total of 14 direct measurements were made in F8480019. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. None of the scan measurements indicated areas of elevated activity. Scan activity ranged from 1566 to 5076 dpm/100 cm 2, based on a surveyor efficiency of 0.5 and no background subtracted. Samples for removable surface activity were all less than 10% of the DCGL as shown in Table 3. Removable surface activity samples were counted for alpha activity and none was detected at the MDC shown in Table 2-1 of Attachment 2.
Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/100 cm F8480019-MOO01 BD 621 F8480019-MOO02BD 658 F8480019-MOO03BD 941 F8480019-MOO04BD 618 F8480019-MOOO5BD 575 F8480019-CO006BD 1841 F8480019-CO007BD 1447 F8480019-MOO08BD 609 F8480019-MOO09BD 664 F8480019-MOOlOBD 637 F8480019-MOOIIBD 578 F8480019-CO012BD 1997 F8480019-MOO13BD 766 F8480019-MOO14BD 840 Mean: 914 Median:. 661 Standard Deviation: 484 Range: 575-1997 Page 4 of 8 FSS Summary Report F8480019
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2 )
F8480019M0001 SM -0.95 F8480019MOO02SM -3.53 F8480019MOO03SM 1.64 F8480019MOO04SM -2.24 F8480019M0005SM -3.53 F8480019M0006SM -2.24 F8480019M0007SM 0.34 F8480019M0008SM -0.95 F8480019M0009SM -2.24 F8480019M0010SM -3.53 F8480019M001 I SM -6.11 F8480019MOO12SM 0.34 F8480019M0013SM 11.97 F8480019M0014SM -4.82 Mean: -1.13 Median: -2.24 Standard Deviation: 4.32 Range: -6.11 to 11.97 Page 5 of 8 FSS Summary Report F8480019
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 4. The sample mean and median values were less than the DCGL. The sample standard deviation was greater than the design standard deviation. Since both values of sigma resulted in a relative shift greater than three (3), no additional samples were required.
Page 6 of 8 FSS Summary Report F8480Q19
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm 2): N/A Ambient Background Used (dpm/100 cm 2): N/A Average Ambient BKG = 0 Actual Direct Measurements (N): 14 Median (dpm/100 cm 2): 661 Mean (dpm/100 cm2) 914 Direct Measurement Standard Deviation 484 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 cm 2): 484 Based on samples and backgrounds.
Maximum (dpm/100 cm 2): 1997 Material Type: N/A Background Subtract Not Applied 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 Total Standard Deviation <= Sigma: Investigate All results <0.5 DCGL Pass the Sign Test? Yes Reject the Null Hypothesis? Yes Does the Survey Unit Pass All Criteria? Investigate All results <0.5 DCGL -
I I_ Survey Unit Passes Page 7 of 8 FSS Summary Report F84800J9
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 3 structure survey and the sample results are consistent with that classification. The variability of the survey results was greater than the characterization data used for survey design. However, no additional samples were required. No potential areas of elevated activity were detected.
==
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. No direct measurements exceeded the DCGL of 43000 dpm/100 cm 2 and none of the removable surface activity measurements exceeded 10% of the DCGL. 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 F8480019 meets the release criteria of 10CFR20.1402.
Page' 8 of 8, FSS Summary Report F8480019
Attachment 1 Maps February 28, 2008 Survey Unit F8480019
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Interior Exterior 15.
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Attachment 2 Instrumentation February 28, 2008 Survey Unit F8480019
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No. Model; Serial No. (dpm/100 cm2 ) (dpm/100 Cm 2 )
M2350; 193700 43-68B; 190294 433 1033 Tennelec; 0401171 N/A 5 dpm a, 11 dpmr N/A Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2)
Investigation Criteria - Direct 21500 Investigation Criteria - Scan 43000 DCGLw 43000 DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8480019
Attachment 3 Investigation February 28, 2008 Survey Unit F8480019 (none required)
Attachment 4 Data Assessment February 28, 2008 Survey Unit F8480019
DF8480019 Gross Activity Sample Results Quantile Plot 0 DCGL = 43000 dpm/1 00cm2 2,500 -io _
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F8480019 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmll00cma 3000 2500 -......- I 2277 2000- 0 0
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