ML082620104
| ML082620104 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 06/02/2008 |
| From: | Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-064 | |
| Download: ML082620104 (18) | |
Text
Rancho Seco Final Status Survey Summary Report June 9, 2008 Auxiliary Building Exterior - South Wall Survey Unit F8132142 Prepared By:
Date:_
FSS Engineer Reviewed By l
(4h(Of6 Lead FSS Engineer Approved By:
Date:
7 Dismantlemen-uperintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8132142, Auxiliary Building Exterior - South 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 cm2 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 cm 2. 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. Direct measurements on the grade elevation showed a mean gross activity level of 373,758 dpm/100 cm2 and a maximum value of 5,800,000 dpm/100 cm2. Direct measurements on the +20' elevation showed a mean gross activity level of 85,408 dpm/100 cm2 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 cm2 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 1 below. The survey unit arid measurement locations are depicted on the maps in Attachment 1. Direct measurement locations were randomly determined and 113 m2 were scanned'for approximately 27%.
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 F8132142
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area:
F813 Survey Unit:
Class:
SU Area (m2):
Evaluator:
DCGL (dpm/100 cm 2):
Area Factor:
Design DCGLemc (dpm/100 cm2):
LBGR (dpm/l oo cm 2):
Design Sigma (dpm/00 cm2):
Type I Error:
Type II Error:
Predominant Nuclide:
Sample Area (m2):
Scan Area (M2):
Scan Coverage (%):
Sign P:
Calculated Relative Shift:
Relative Shift Used:
N-Value:
Design N-Value + 20%:
Design Min Samples N:
Grid Spacing L:
2142 3
425.6 Gary Frank 43000 N/A N/A 21500 342 0.05 0.05 Cs-137 N/A 113 27%
1.645 1.645 0.99865 62.8 3
11 14 14 N/A Auxiliary Building Exterior
- South Wall Structure Surface LTP Tablei5-4 Gross Activity DCGL Class 3 Class 3 Default = 50% DCGL Class 3 Class 3 Uses 3.0 if Relative Shift is
>3 NUREG-1575 Table S5-5 ClaIs 3 Class 3 Page 3 of 8 FSS Summary Report F8132142
Survey Results:
A total of 14 direct measurements were made in F8132142. 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 measurements were performed with results ranging at or less than the MDC shown in Table 2-1. 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)
F8132142-CO001 BD 1349 F8132142-CO002BD 1261 F8132142-CO003BD 923 F8132142-CO004BD 1442 F8132142-CO005BD 747 F8132142-CO006BD 1115 F8132142-CO007BD 1561 F8132142-CO008BD 1328 F8132142-CO009BD 1219 F8132142-COOIOBD 1473 F8132142-COOIIBD 1473 F8132142-CO012BD 1266 F8132142-CO013BD 1437 F8132142-CO014BD 1489 Mean:
1292 Median:
1338 Standard Deviation:
231 Ranqe:
747-1561 Page 4 of 8 FSS Summary Report F8132142
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)
F8132142C0001 SM F8132142C0002SM F8132142C0003SM F8132142C0004SM F8132142C0005SM F8132142C0006SM F8132142C0007SM F8132142C0008SM F8132142C0009SM F8132142CO010SM F8132142C001 1 SM F8132142C0012SM F8132142C0013SM F8132142C0014SM Mean:
Median:
Standard Deviation:
Ranqe:
8.09
-3.53
-3.53
-2.24
-2.24
-0.95 4.22
-0.95
-3.53 4.22 0.34
-0.95 4.22
-0.95 0.16
-0.95 3.61
-3.53 to 8.09 Page 5 of 8 FSS Summary Report F8132142
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 F8132142
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/lOO cm2):
1338 Mean (dpm/100 cm2):
1292 Direct Measurement Standard Deviation 231 (dpm/1 00 cm2):
Total Standard Deviation (dpm/100 cm2):
231 Based on samples and backgrounds.
Maximum (dpm/100 cm 2):
1561 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 Page 7 of 8 FSS Summary Report F8132142
.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 the data quality objectives were met.
It is concluded that survey unit F8132142 meets the release criteria of 1 0CFR20.1402.
Page 8 of 8 FSS Summary Report F8132142 Maps June 9, 2008 Survey Unit F8132142
1_9r-4" o
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\\Covered in F8132143 6 O(4GS) 05GS OG 009GS 1 0_GS_
3_02142M Aux Bldg. Ext. South Wall Looking North 425.6 m2' 00
~F8132142-Ml
00 4l) 19T-4 1 2 3
4 5
6 7
8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30" 31 32 33 Aux Bldg. Ext. South Wall Looking North 425.6 m2 F8132142-M2 Instrumentation June 9, 2008 Survey Unit F8132142
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No.
Model; Serial No.
(dpm/100 cm2 )
(dpm/100 cm2 )
M2350; 149789 43-68B; i48633 433 1033 Tennelec; 0401171 N/A 6 dpm a, 12 dpm N/A Detector MDC Serial No.
(dpm/100cm2) 1090 Cs-i137 ISOCS 1983920 832 Co-60 832 Co-60 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 F8132:142 Investigation June 9, 2008 Survey Unit F8132142 (none required)
Data Assessment June 9, 2008 Survey Unit F8132142
CD)
C/3 Cl) 00 F8132142 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm2 4-1,800 1,600 1,400 1,200 1,000 800 600 400 200 0
1338 0
20 40 60 Percentile 80 100 Direct Measurements (dpm/100cm2) -
median
. _ 75th Percentile.
50th Percentile
0 0
FBI 32142 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpm/100cm=
U p
O3 O0 ni 00 NJ
.2500 E2000 -
U C 1500-E
- 0 1000 V
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0 0
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0 1986 1 1292 1*597 I
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Measurement Locations o
Gross Activity -
Average -
"+3StDev" -
"-3StDev "
CD 0-rI)
CD) kj)
F8132142 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm2 7
6 5
Q)
C0 4-3 2
0 N-Bins - Upper End Value (dpm/lOOcm2)