ML082620147
| ML082620147 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 07/30/2008 |
| From: | Tallman D Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-064 F8130102 | |
| Download: ML082620147 (27) | |
Text
Rancho Seco Final Status Survey Summary Report June 10, 2008 AB -20' Corridor room 10 upper walls and ceiling Survey Unit F8130102 Prepared By: Dan A. Tallman z-ý." Date: June 10, 2008 FSS Engineer Reviewed By:IŽ*Ž L" ate: 71147a Lead FSS Engineer Approved By: Date: 7,**3 Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8130102, AB -20' Corridor room 10 upper walls and ceiling Survey Unit
Description:
Operating History: The Auxiliary Building is a reinforced concrete structure that contained the RadWaste processing and supporting systems. The building contained six main elevations. Residual radioactive material was known to be present on all levels of the interior of the building. Operating records and the HSA document several events with the potential for a release of radioactivity inside this structure.
Site Characterization: Direct measurements were made of each of the interior elevation surfaces as well as the exterior surfaces of the structure. These measurements confirmed the presence of plant-derived radionuclides. Direct measurements on the -20' elevation showed a mean gross activity level of 247,831 dpm/100 cm 2 and a maximum value of 10,080,000 dpm/100 cm 2, Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the upper walls and ceiling of room 10 in the interior of the auxiliary building was determined to be a Class 2 area.
HSA Events: HSA Report pg. 63.
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 167 m2 were scanned for approximately 70% 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 .
Page 2 of 8 FSS Summary Report F8130102
Table 1. Survey Unit Design Parameters Survey ,Design Value Comment Parameter Survey Area: F8 f3 AB -20' Corridor room 10 upper walls and ceiling Survey Unit: 0102 Structure Surface Class: 2 LTP Table 5-4 SU Area (m2): 239.4 Evaluator: D.A.Tallman DCGL (dpm/100 cm 2): 43000 Gross Activity DCGL Area Factor: N/A Class 2 Design DCGLemc N/A Class 2 (dpm/100 cm 2 ):
LBGR (dpm/100 cm 2): 21500 Default = 50% DCGL Design Sigma (dpm/100 cm 2 ): 12035 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): 14 Class 2 Scan Area (M2 ): 167 Scan Coverage (%): 70% Class 2 Zj." : 1.645 ZI-0 : 1.645 Sign P: 0.955435 Calculated Relative Shift: 1.7 Relative Shift Used: 1.7 Uses 3.0 if Relative Shift is
>3 N-Value: 14 Design N-Value + 20%: 17 NUREG-1575 Table 5-5 Design Min Samples N: 17 Class 2 Grid Spacine L: 3.7 Class 2 Page 3 of 8 FSS Summary Report F8130102
Survey Results:
A total of 17 direct measurements were made in F8130102. 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 2067 to 31442 dpm/100 cm2 , based on a surveyor efficiency of 0.5 and no background subtracted. ISOCS scan activity on the ceiling all less than MDA for both Cs-137 and Co-60. 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 .
Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/100 cm F8130102-CO001BD 1696 F8130102-CO002BD 1717 F8130102-CO003BD 1644 F8130102-CO004BD 1764 F8130102-CO005BD 1810 F8130102-CO006BD 2080 F8130102-CO007BD 1421 F8130102-CO008BD 1567 F8130102-CO009BD 1748 F8130102-CO01OBD 1426 F8130102-CO011BD 1572 F8130102-CO01 2BD 1758 F8130102-CO013BD 1624 F8130102-CO014BD 1411 F8130102-CO015BD 1556 F8130102-CO016BD 1655 F8130102-CO017BD 1152 Mean: 1624 Median: 1644 Standard Deviation: 205 Rannge: 1152-2080 Page 4 of 8 FSS Summary Report F8130102
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/1 0O, cm 2 )
F8130102CO010SM 1.64 F8130102C0001SM -2.24 F8130102C0002SM 4.22 F8130102C0003SM -3.53 F8130102CO004SM -3.53 F8130102C0005SM -2.24 F8130102C0006SM 1.64 F8130102C0007SM -2.24 F8130102CO008SM -2.24 F8130102CO009SM 2.93 F8130102C0010SM -2.24 F8130102CO011SM 2.93 F8130102C0012SM 26.17 F8130102C0013SM 27.46 F8130102CO014SM 0.34 F8130102COOI5SM -2.24 F8130102C0016SM 9.38 F8130102C0017SM 0.34 Mean: 3.14 Median: 0.34 Standard Deviation: 9.22 Range: -3.53 to 27.46 Page 5 of 8 FSS Summary Report F8130102
Survey Unit Data Assessment:
The survey design required 17 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 less than the design standard deviation so no additional samples were required.
Page 6 of 8 FSS Summary Report F8130102
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpmIO00 cm 2 ): N/A Ambient Background Used (dpm/100 cm2): N/A Average Ambient BKG = 0 Actual Direct Measurements (N): .17 Median (dpm/100 cm 2): 1644 Mean (dpm/100 cm 2 ): 1624 Direct Measurement Standard Deviation 205 2
(dpm/100 cm ):
Total Standard Deviation (dpm/100 cm 2): 205 Based on samples and backgrounds.
Maximum (dpm/100 cm 2 ): 2080 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 17 S+ Value: 17 Critical Value: 12 Sufficient Samples Collected: Yes Maximum Value < DCGL: Yes Median Value < DCGL: Yes Mean Value < DCGL: Yes Maximum Value < DCGLemc: N/A Class 2 Total 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 F8130102
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), the ALARA criterion has been met.
Changes in Initial Survey Unit Assumptions:
The survey unit was designed as a Class 2 structure 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.
==
Conclusion:==
The FSS of this survey unit was properly designed as a Class 2 survey based on Table 5-4 of the LTP not withstanding the design sigma value usage described on page two. 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 F8130102 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F8130102
Attachment I Maps June 10, 2008 Survey Unit F8130102
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- -I 172.7 m2
.1 Walls-Stairs 12.9 m22 Floor- 0.0 m Total - 239.4 m 2
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Attachment 2 Instrumentation June 10, 2008 Survey Unit F8130102
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No. Model; Serial No. (dpmll00 cm 2 ) (dpm/100 cm 2 )
M2350; 193700 43-68B; 190294 433 1033 M2350; 203481 43-68B; 148629 433 1033 M2350; 193700 43-116-IB; 216072 491' 739' Tennelec; 0401171 N/A 6 dpm a, 12 dpm3 N/A A Juncture - concrete Instrument Detector MDC Scan Model; Serial No. Model; Serial No. (dpm/100 cm 2 )
19839201 1160 - Cs137 ISOCS 882 - Co60 3920_2mconcrete geometry 12 m2 FOV Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2 )
Investigation Criteria - Direct 43000 Investigation Criteria - Scan 43000 DCGLW 43000 DCGLEMC N/A Page 2 of 2 Ant. 2 Instrumentation F8130102
Attachment 3 Investigation June 10, 2008 Survey Unit F8130102
. (none required)
Attachment 4 Data Assessment June 10, 2008 Survey Unit F8130102
- F8130102 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm2 2,500 2,000 1644 1,500 00 4-1,000 500 C#2 Il 0
0 20 40 60 80 104 ntll Percentile
- Direct Measurements (dpm/1l00cm2) - median - - -75th Percentile . - 50th Perce
0 F8130102 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpm/100cm" 2500 2238 0
E 2000
- 0. 0 0 0 0 0
- 1500-0 0 1 1024 0
- t-- --- - . - -a a 1 1010 500 0
i i i i i i i i i i i i i i i i M to Im Ca 8mw w cc w to in M 8m M L0o Measurement Locations 00 I0 o Gross Activity - Average - - "+3StDev" - - "-3SIDev 0
(D F81 30102 Gross Activity Frequency Plot DCGL = 43000 dprn/ 00cm2 8
7 CD 6
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5 LL C 4 j-En 3
1-0-
00 Bins - Upper End Value (dpm/1 00cm2) w