ML091000381
| ML091000381 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 06/24/2008 |
| From: | Park G Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097, F8132133 | |
| Download: ML091000381 (19) | |
Text
Rancho Seco Final Status Survey Summary Report June 24, 2008 0' Auxiliary Steam Support, Class 1 Area Survey Unit F8132133 Prepared By-- Date: 6--P2qJ FSS Engineer Reviewed By: \ Date:,t/'A aS Lead FSS Engineer Approved By: 2"7 Date: -7 *'
Dismantlement SWerintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT SurveyUnit:
F8132133, 0' Auxiliary Steam Support, Class 1 Area Survey Unit
Description:
Operating History: The reinforced concrete structure 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. One report documented contamination of the auxiliary building roof. The roof was later replaced.
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 -47' elevation showed a mean gross activity level of 320,071 dpm/100 cm 2 and a maximum value of 5,720,000 dpm/100 cm 2. Direct measurements on the -29' elevation showed a mean gross activity level of 544,756 dpm/100 cm 2 and a maximum value of 11,370,000 dpm/100 cml. 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 cm2 . Direct measurements on the grade elevation showed a mean gross activity level of 373,758 dpm/100 cm 2 and a maximum value of 5,800,000 dpm/100 cm 2. Direct measurements on the +20' elevation showed a mean gross activity level of 85,408 dpm/l100 cm 2 and a maximum value of 1,900,000 dpm/100 cm 2. Direct measurements on the +40' elevation showed a mean gross activity level of 3,288 dpm/100 cm 2 and a maximum value of 24,781 dpmi/100 cm 2. Direct measurements on the building exterior, including the mezzanine roof, showed a mean gross activity level of 1,897 dpm/100 cm 2 and a maximum value of 2,990 dpm!100 cm 2. (The roof had been replaced prior to the classification survey.) Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the interior of the auxiliary building was determined to be a Class 1, 2 area and the exterior was a Class 2,3.
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 4 m2 were scanned for 100% 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 F8132133
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F813 0' Auxiliary Steam Support Survey Unit: 2133 Structure Surface Class: 1 LTP Table 5-4 SU Area (m2): 4 Evaluator: Gary Frank DCGL (dpm/100 cm 2): 4-JUUU Gross Activity DCGL Area Factor: 48.3 Class, 1 Design DCGLemc 2080217 Class 1 2
(dpm/100 cm ):
LBGR (dpm/100 cm 2): 21500 Default = 50% DCGL Design Sigma (dpm/100 cm 2): 342 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): 0.28 Class 1 Scan Area (m ): 2 4 Scan Coverage (%): 100% Class 1 Zl-, : 1.645 Zj-P : 1.645 Sign P: 0.99865 Calculated Relative Shift: 62.9 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 1 Grid Spacina L: 0.5 Class 1 Page 3 of 8 FSS Summary Report F8132133
Survey Results:
A total of 14 direct measurements were made in F8132133. 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 6756 to 13197 dpm/100 cm 2 , based on a surveyor efficiency of 0.5 and no background subtracted. Gamma particle scan measurements ranged from 4383 to 7006 cpm. 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/1O0 cm F8132133-COOOI BD 1707 F8132133-CO002BD 2148 F8132133-CO003BD 2199 F8132133-CO004BD 2184 F8132133-CO005BD 1997 F8132133-CO006BD 1987 F8132133-CO007BD 1873 F8132133-CO008BD 2853 F8132133-CO009BD 3932 F8132133-CO01OBD 2018 F8132133-CO011BD 1878 F8132133-CO012BD 1997 F8132133-CO013BD 1976 F8132133-CO014BD 1821 Mean: 2183 Median: 1997 Standard Deviation: 571 Range: 1707-3932 Page 4 of 8 FSS Summary Report F8132133
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpmlO00 cm 2)
F8132133C0001SM -0.95 F8132133C0002SM -0.95 F8132133C0003SM 1.64 F8132133C0004SM 1.64 F8132133C0005SM .2.93 F8132133C0006SM -2.24 F8132133C0007SM -2.24 F8132133CO008SM -4.82 F8132133C0009SM -2.24 F8132133COOIOSM 1.64 F8132133C001 I SM -0.95 F8132133C0012SM -0.95 F8132133C0013SM -3.53 F8132133C0014SM -3.53 Mean: -1.04 Median: -0.95 Standard Deviation: 2.29 Range: l I -4.82 to 2.93 Page 5 of 8 FSS Summary Report ,F8132133
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 but no additional samples were required, 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 .F8132133
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100cm2 ): N/A Ambient Background Used (dpm/100 cm 2): N/A Average Ambient BKG 0 Actual Direct Measurements (N): 14 Median (dpm/ oo cm 2): 1997 Mean (dpm/IOO cm2): 2183 Direct Measurement Standard Deviation 571 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 cm 2): 571 Based on samples and backgrounds.
Maximum (dpm/100 cm 2): 3932 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: Yes Class 1 Total Standard Deviation <= Sigma: Investigate All values <DCGLw Pass the Sign Test? Yes Reject the Null Hypothesis? Yes Does the Survey Unit Pass All Criteria? Investigate Survey Unit Passes Page 7 of 8 FSS Summary Report F8132133
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 1 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. 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. 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 F8132133 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F8132133
Attachment 1 Maps June 24, 2008 Survey Unit F8132133
F8132133 - Beta Scans 0
oI 00 0'-0" ELEV. Auxiliary Steam Supports F8132133 - M1
F8132133 - Beta Direct 0
Gamma Backgrounds are fl) obtained from the beta direct points 1 through 10 in order.
00 t'Jo 0'-O" ELEV. Auxiliary Steam Supports F8132133- M2
F8132133 - Gamma Partici e Scans 0
4*
0' Elev F 744 69.1 00 0'-0" ELEV. Auxiliary Steam Supports Uj F8132133 - M3
Attachment 2 Instrumentation June 24, 2008 Survey Unit F8132133
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No. Model; Serial No. (dpmll00 cm2 ) (dpmll00 cm 2 )
M2350; 193715 44-10; 171374 N/A 5.2 pCi/g M2350; 193715 43-68B; 160703 433 1033 Tennelec; 0401171 N/A 6 dpm a, 12 dpmr N/A Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2 )
Investigation .Criteria - Direct 2080217 Investigation Criteria - Scan 2080217 DCGLw 43000 DCGLEMC 2080217 Page 2 of 2 Att. 2 Instrumentation F8132133
Attachment 3 Investigation June 24, 2008 Survey Unit F8132133 (none required)
Attachment 4 Data Assessment June 24, 2008 Survey Unit F8132133
(rQ F8132133 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm2 4,500 4,000 3,500 3,000 2,500 00 2,000 1997 i 1,500 1,000 Uj 500 cn 0
0 20 40 60 80 100 Percentile
- Direct Measurements (dpm/lQOcrn2) -- median - - - 75th Percentile - -- - 50th Percentile
CD o F81 32133 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmlle00cm 4500 4000 .m. . . . . . a . a a - - a a a a a a
- 3896 E
0 3500 g3000-C0 E*2500 L - -o - - - 2183 S 2000 o 0N. o 0 p 15 00 o W
~tu ooo aD 500 ------------------------------- 471 o a 0 0 0 C C 0 0 V- 0 0 0 0 o 0 0 0 0. a C 0 0 r a a r a So 0o 0 0 0 0 0 0 0 0 0 0 0 U U U U U U U U U U U U U U Measurement Locations L -..... ...
7... Gr
. ..oss
. .Activity
. .... . .... Average
. . . . . . . - ..- . "+3StDev"
... ....... -3Ste .. ..
k)J
('3
(D~
F8132133 Gross Activity Frequency Plot DCGL = 43000 dpm/l 00cm2 12 11 10 Ci 9 8
ci) 7 LL 0 6 5
cj~
4 3
2 (TI 1
0 0l-" 8 (Tv 00 WN Bins - Upper End Value (dpm/1 00cm2)