ML091000371
| ML091000371 | |
| 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, F8132144 | |
| Download: ML091000371 (18) | |
Text
Rancho Seco Final Status Survey Summary Report February 11, 2009 Auxiliary Building Exterior Wall North Survey Unit F8132144 Prepared By:%2, Date:2,ý'/)
7OO0 FSS Engineer Reviewed By:___________
Date:
09 Lead FSS Engineer Approved By:
Date:_______
Dismantlement Su erintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8132144, Auxiliary Building Exterior Wall North 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/l'00 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 cm2 and a maximum valueiof 10,080,000 dpmr/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/100 cm 2 and a maximum value of 1,900,000 dpm/100 cm2. 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 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 cm2. (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 randomly determined and 113 m2 were scanned for approximately 30%
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 F8132144
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/100 cm 2):
Design Sigma (dpm/100 cm2):
Type I Error:
Type II Error:
Predominant Nuclide:
Sample Area (m2):
Scan Area (M2 ):
Scan Coverage (%):
Zl-, :
Sign P:
Calculated Relative Shift:
Relative Shift Used:
N-Value:
Design N-Value + 20%:
Design Min Samples N:
Grid Spacing L:
2144 3
376 Gary Frank 43000 N/A N/A 21500 342 0.05 0.05 Cs-137 N/A 113 30%
1.645 1.645 0.99865 62.8 3
11 14 14 N/A Auxiliary Building Exterior Wall North Structure Surface LTP Table 5-4 Gross Activity DCGL Class 3 Class 3 Default = 50% DCGL DTBD-06-001, Table 5-4D Class 3 Class 3 Uses 3.0 if Relative Shift is
>3 NUREG-1 575 Table 5-5 Class 3 Class 3 Page 3 of 8 FSS Summary Report F8132144
Survey Results:
A total of 14 direct measurements were made in F8132144. 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 707 to978 dpm/100 cm 2 for Cs-137, and 502 to 776 dpm/100 cm2 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 Activit (dpm/100 cm F8132144-COOOIBD F8132144-CO002BD F8132144-CO003BD F8132144-CO004BD F8132144-CO005BD F8132144-CO006BD F8132144-CO007BD F8132144-CO008BD F8132144-Co009BD F8132144-Co01OBD F8132144-CO01 I BD F8132144-CO01 2BD F8132144-CO01 3BD F8132144-Co01 4BD Mean:
Median:
Standard Deviation:
Range:
1603 1535 1504 1629 1841 1805 1608 1432 1582 1520 1494 1473 1567 1561 1582 1564 116 1432-1841 Page 4 of 8 FSS Summary Report F8132144
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm2)
F8132144C0001SM
-1.58 F8132144C0002SM 1
F8132144C0003SM
-0.29 F8132144C0004SM
-0.29 F8132144C0005SM
-0.29 F8132144C0006SM
-2.88 F8132144C0007SM
-1.58 F8132144C0008SM
-1.58 F8132144C0009SM
-0.29 F8132144C0010SM
-0.29 F8132144C0011SM 3.58 F8132144C0012SM 2.29 F8132144C0013SM
-1.58 F8132144C0014SM 3.58 Mean:
-0.02 Median:
-0.29 Standard Deviation:
1.97 Range:
-2.88 to 3.58 Page 5 of 8 FSS Summary Report F8132144
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 F8132144
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):
1564 Mean (dpm/100 cm 2):
1582 Direct Measurement Standard Deviation 116 (dpm/100 cm2):
Total Standard Deviation (dpm/100 cm 2):
116 Based on samples and backgrounds.
Maximum (dpm/100 cm 2):
1841 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 F8132144
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 actiý,ity 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 cm2 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 F8132144 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F8132144 Maps February 11, 2009 Survey Unit F8132144
CD~
Auxiliary Building ISOCS Scans L
69'-9" F
~62'-1" 1~
23'
-e 63' 40, 00 Auxiliary Bldg. Exterior North Wall Looking South 4056 ft 2 376.8 m2 F8132144-MI
(0 0-Auxiliary Building Beta Direct/Smear Scans E
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10 15 20 25 30 35 40 45 50 55 60 65 70 Looking South 4056 ft2 376.8 m2 F8132144-M2 Instrumentation February 11, 2009 Survey Unit F8132144
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; 175834 43-68B; 148634 433 1033 Tennelec; 0401171 N/A 5 dpm ca, 11 dpmf3 N/A 978 Cs-137 ISOCS; 1983920 N/A N/A 77 Cs-60 776 Co-60 Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2)
Investigation Criteria - Direct 21500 Investigation Criteria - Scan 43000 Investigation Criteria - ISOCS 21500 DCGLw 43000 DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8132144 Investigation February 11, 2009 Survey Unit F8132144 (none required)
Data Assessment February 11, 2009 Survey Unit F8132144
1'0 0F8132144 Gross Activity Sample Results Quantile Plot 0
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