ML091000383
| ML091000383 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 02/11/2009 |
| From: | Frank G Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097, F8132143 | |
| Download: ML091000383 (18) | |
Text
Rancho Seco Final Status Survey Summary Report February 11, 2009 Auxiliary Building Exterior East Wall Survey Unit F8132143 Prepared By: 2 %\' -* Date:________
FSS Engineer Reviewed By: \ 4 Date: "-7-c Lead FSS Engineer Approved By: -7 Date: 7 Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8132143, Auxiliary Building Exterior East Wall 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!l 00 cm 2 . Direct measurements on the -20' elevation showed a mean gross activity level of 247,831 dpm/100 cm2 and a maximum value of 10,080,000 dpm/100 cm 2. 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/100 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/l100 cm 2 and a maximum value of 24,781 dpm/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 I below. The survey unit and measurement locations are depicted on the maps in Attachment 1. Direct measurement locations were randomly determined and 396 m2 were scanned for approximately 97%
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 F8132143
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F813 Auxiliary Building Exterior East Wall Survey Unit: 2143 Structure Surface Class: 3 LTP Table 5-4 SU Area (mE): 410 Evaluator: Gary Frank DCGL (dpm/1O0 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): 342 DTBD-06-001, Table 5-4D Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): N/A Class 3 Scan Area 2 (Mi ): 396 Scan Coverage (0/): 97% Class 3 1.645 1.645 Sign P: 0.99865 Calculated Relative Shift: 62.8 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 Spacina L: N/A Class 3 Page 3 of 8 FSS Summary Report F8132143
Survey Results:
A total of 14 direct measurements were made in F8132143. 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. ISOCS scan activity ranged from 662 to 978 dpm/100 cm 2 for Cs-137 and 472 to 739 dpm/100 cm 2 for 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 )
F8132143-CO001BD 1369 F8132143-C0002BD 1115 F8132143-C0003BD 1634 F81321.43-CO004BD 1022 F8132143-CO005BD 1390 F8132143-CO006BD 1203 F8132143-CO007BD 1437 F8132143-CO008BD 1276 F8132143-CO009BD 1203 F8132143-CO01OBD 1053 F8132143-CO011BD 1364 F8132143-CO012BD 1022 F8132143-CO013BD 1048 F8132143-CO014BD 1261 Mean: 1243 Median: 1232 Standard Deviation: 183 Range: 1022 - 1634 Page 4 of 8 FSS Summary Report F8132143
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)
F8132143C0001SM -0.29 F8132143C0002SM -0.29 F8132143C0003SM 2.29 F8132143C0004SM -1.58 F8132143C0005SM 1 F8132143C0006SM -0.29 F8132143C0007SM -0.29 F8132143C0008SM 1 F8132143C0009SM 1 F8132143C0010SM -0.29 F8132143C0011SM -1.58 F8132143C0012SM 2.29 F8132143C0013SM -0.29 F8132143C0014SM -0.29 Mean: 0.17 Median: -0.29 Standard Deviation: 1.2 Range: -1.58 to 2.29 Page 5 of 8 FSS Summary Report F8132143
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 less than the design standard deviation so no additional samples were required.
Page 6 of 8 FSS Summary Report F8132143
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 2 (dpm/100 cm ): 1232 2
Mean (dpm/100 cm ) 1243 Direct Measurement Standard Deviation 183 2
(dpm/100 cM ):
Total Standard Deviation (dpm/100 cm 2): 183 Based on samples and backgrounds.
Maximum (dpm/100 cm 2): 1634 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: Yes Pass the Sign Test? Yes Reject the Null Hypothesis? Yes Does the Survey Unit Pass All Criteria? Yes I Page 7 of 8 FSS Summary Report F8132143
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 3 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. 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 thedata quality objectives were met.
It is concluded that survey unit F8132143 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F8132143
Attachment 1 Maps February 11, 2009 Survey Unit F81321,43
CD Auxiliary Building East Wall
-ISOCS Scans East end of south wall
- i included in this survey...
- 63 C ciNot In
- ,. // /This Survey ,,N/j /4//.
20' Reflected Overhang// ///-/ '"/// /'*/ /$/6,'
785 ft' 7219 nl Aus, Bldg Ext East Wall Looking West F8132143-M 3,629 ft' 33779 P 00 FI34-
(D Auxiliary Building East Wall Beta Direct 70-03 65 --
60-55-- 07 50-457 40- 'OT 09 35--
307-L05 L__] )6 25-Bottom of overhang 207-04 15-11 13 10-- 10
.5--
08 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 00 e
F8132143-M2
Attachment 2 Instrumentation February 11, 2009 Survey Unit F8132143
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; 149789 43-68B; 161415 433 1033 Tennelec; 0401171 N/A 5 dpmua, 11 dpmr3 N/A 0N/A N/A 978 Cs-137 ISOCS; 1893920 N739 Co-60 Table 2-2. Investigation Criteria and DCGL Value Param eter (dpm/100 cm 2 )2 V l eC Investigation Criteria - Direct 21500 Investigation Criteria- Scan 43000 DCGLw 43000 DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8132143
Attachment 3 Investigation February 11, 2009 Survey Unit F8132143 (none required)
Attachment 4 Data Assessment February 11, 2009 Survey Unit F8132143
IiG F8132143 Gross Activity Sample Results Quantile Plot 0 DCGL = 43000 dpm/100cm2 1,800 1,600 1,400 1232 1,200 Cl)
I 4-1,000 800 U.*
CI) 600 400 (TI 200 n TIJ I I !
0 20 40 60 80 100 Percentile 00 SDirect Measurements (dpm/1 Ocm2) median 75th Percentile - - - - 50th Percentile o)
CD
('3 a F8132143 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmll00cm=
2000 1800 - 1792 E 1600 -
00 a 1400- o 0 0C 0 0 1 0 . 1243
> 1200-E 0 0 0
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o800 l - " w - f w a 0m M w = " w a -a a M " - -M -. . - -= m - 1 894 600-C'D
< 400-200 0
o 0 0 0 0 Cl 0 0 0 0 0 0 0 0 r CV f0 0 0 0 fl %
r o 0 0 0 0 0 0 0 r r r r V 0 0 00 00 000 Ut) 0 0 0 U U U U U U U U U U U U U U Measurement Locations 00 o0 Gross Activity - Average - - "+3StDev"-" "-3SIDev":
L'J t'3
-p-0ýt F81 32143 Gross Activity Frequency Plot DCGL = 43000 dpm1l 00cm 2 6
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0 Bins - Upper End Value (dpm/l00cm2)