ML082620156
| ML082620156 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 07/02/2008 |
| From: | Stein M Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| F8130711, MPC&D 08-064 | |
| Download: ML082620156 (23) | |
Text
- 1 A.1 4.
Rancho Seco Final Status Survey Summary Report July 2, 2008 East Heat Removal Cooler Room Between Columns 9.5 and 9.7, Room 051 Floor and Lower Walls Survey Unit F8130711 Prepared By:
Date:"
FSS Engineer Reviewed ByYL&
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lý,
Date:
Lead FSS Engineer Approved By:
Date:
7 Dismantlemen S erintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F813071 1, East Heat Removal Cooler Room Between Columns 9.5 and 9.7, Room 051 Floor and Lower Walls Survey Unit
Description:
Operating History: The East Heat Removal Cooler Room is located on the -20' elevation of the Auxiliary Building. The Auxiliary Building is a reinforced concrete structure that, during power operations, contained the Radwaste processing and supporting systems.
The building has six main elevations. Residual levels of surface radioactivity were detected on all interior elevations 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 taken on each interior elevation of the Auxiliary Building. These measurements corifirmed the presence of plant-derived radionuclides. Direct measurements taken 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/l00 cm2.
Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the interior surfaces of the Auxiliary Building were determined primarily to be a Class 1 for the floors and lower walls (bottom 2 meters of the walls), and Class 2 for the upper walls and ceiling. Inside the East Heat Removal Cooler Room there were a number of areas on the floor and lower walls where the gross surface activity levels were higher than the DCGL prior to remediation. Therefore, a Class 1 final status survey, was performed on the floor and lower walls of the East Heat Removal Cooler Room between Columns 9.5 and 9.7, Room 051.
HSA Events: HSA Report pg. 63.
Survey Unit Design Information:
The Survey Unit Design Parameters are presented in Table'l 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 140 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 F8130711
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 cm2):
Design Sigma (dpm/100 cm2):
Type I Error:
Type II Error:
Predominant Nuclide:
Sample Area (m2):
Scan Area (M2):
Scan Coverage (%):
Zjp:
Sign P:
Calculated Relative Shift:
Relative Shift Used:
N-Value:
Design N-Value + 20%:
Design Min Samples N:
Grid Spacing L:
0711 1
140 Michael Stein 43000 3.5 150500 21500 12035 0.05 0.05 Cs-137 7
140 100%
1.645 1.645 0.955435 1.7 1.7 14 17 20 2.6 East Heat Removal Cooler Room Between Columns 9.5 and 9.7, Room 051 Floor and Lower Walls Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class 1 Default = 50% DCGL Class 1 Class 1 Uses 3.0 if Relative Shift is
>3 NUREG-1575 Table 5-5 Class 1 Class 1 I
Page 3 of 8 FSS Summary Report F8130711
Survey Results:
A total of 22 direct measurements were made in F8130711. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. One of the scan measurements indicated an area of elevated activity. Scan activity ranged from 2,893 to 523,819 dpm/100 cm2, based on a surveyor efficiency of 0.5 and no background subtracted. 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 Attachment 2.
Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/100 cm F8130711-CO001BD 2158 F8130711-CO002BD 3128 F8130711-C0003BD 4648 F8130711-CO004BD 2080 F8130711-C0005BD 2173 F8130711-C0006BD 3584 F8130711-CO007BD 2314 F8130711-C0008BD 1914 F8130711-CO009BD 3092 F8130711-C001OBD 2075 F8130711-CO011BD 1924 F8130711-CO012BD 2116 F8130711-CO013BD 1831 F8130711-Co014BD 3641 F8130711-CO015BD 1888 F8130711-CO016BD 3621 F8130711-CO017BD 1821 F8130711-CO018BD 1971 F8130711-CO019BD 1561 F8130711-CO02OBD 1530 F8130711-CO021BD 1546 F8130711-CO022BD 1748 Mean:
2380 Median:
2077 Standard Deviation:
847 Range:
1530-4648 Page 4 of 8 aFSS Summary Report F8130711
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2) "
F8130711CO001SM F8130711 C0002SM F8130711 C0003SM F8130711 C0004SM F8130711 C0005SM F8130711 C0006SM F8130711C0007SM F8130711 C0008SM F8130711 C0009SM F8130711CO010SM F8130711CO011SM F8130711C0012SM F8130711CO013SM F8130711CO014SM F8130711CO015SM F8130711CO016SM F8130711Co017SM F8130711Co018SM F8130711CO019SM F8130711 C0020SM F8130711CO021SM F8130711 C0022SM Mean:
Median:
Standard Deviation:
Range:
-2.24
-2.24 5.51 1.64 1.64
-2.24 1.64 1.64 1.64 1.64
-0.95 0.34 1.64
-0.95
-2.24 4.22
-4.82
-2.24 9.38 10.68 0.34 14.55 1.75 1.64 4.7
-4.82 to 14.55 Page 5 of 8 FSS Summary Report F8130711
Survey Unit Data Assessment:
The survey design required 20 direct measurements for the Sign Test. In actuality, 22 direct measurements were obtained. 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 F8130711
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm 2):
N/A Ambient Background Used (dpm/100 cm2):
N/A Average Ambient BKG = 0 Actual Direct Measurements (N):
22 Median (dpm/100 cm 2):
2077 Mean (dpm/100 cm 2):
2380 Direct Measurement Standard Deviation 847 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 cm 2):
847 Based on samples and backgrounds.
Maximum (dpm/100 cm 2):
4648 Material Type:
N/A Background Subtract Not Applied Sign Test Final N Value:
22 S+ Value:
22 Critical Value:
15 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:
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 F8130711
Survey Unit Investigations and Results:
One investigation (scan grid COM32BS) was required for the scan measurements and the results are reported in Attachment 3. Investigation of the area resulted in the decision to perform additional remediation. The investigation results in Attachment 3 represent the residual radioactivity levels achieved after additional remediation. The EMC unity rule was not exceeded as shown in Table 3-1.
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 and the EMC criterion has been met), 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 less than the characterization data used for survey design. One potential area of elevated activity was detected and evaluated as shown in Attachment 3. 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 cm2 and none of the removable surface activity measurements exceeded 10% of the DCGL.
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 F8130711 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F813 0711 Maps July 2, 2008 Survey Unit F8130711
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DING SHEET I OF 1 TC HILL Instrumentation July 2, 2008 Survey Unit F8130711
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No.
Model;-Serial No.
(dpm/100 cm 2 )
(dpm/100 cm 2 )
M2350; 203486 43-68B; 190476 433 1033 M2350; 175834 43-68B; 148634 433 1033 M2350; 175834 43-116-1B; 190642 796 3258 M2350; 203486 43-116-IB; 190173 491 f3Juncture 739 P Juncture Tennelec; 0401171 N/A 5.9 dpm a, N/A Ine 4 7 N11.7 dpm P3 The scan and static MDC's provided represent the most conservative MDC values for the survey conducted.
Table 2-2. Investigation Criteria and DCGL Parameter Value (dpm/100 cm2)
Investigation Criteria - Direct 150500 Investigation Criteria - Scan 150500 DCGLw 43000 DCGLEMC 150500 Page 2 of 2 Att. 2 Instrumentation F8130711 Investigation July 2, 2008 Survey Unit F8130711
Table 3-1 Survey Unit Investigation Investigation Investigation DCGLemc Gd Investigation Initial Value Ivestatin Elevated Area DCGLemc Result Unity Level (cpm)
(cpm)
(cpm)
Area (n 2)
Factor (dpm/1 OOcm 2)
Fraction C0032BS 21,024 71,405 569 N/A N/A N/A 4,174 0.00 DCGL =
SU Mean =
0.06 Survey Unit Remainder 43,000 2,380 EMC Unity Sum 0.06 The grid above was initially greater than survey unit design investigation level. Investigation of grid C0032BS resulted in the decision to perform additional remediation. The investigation results above represent the residual radioactivity level after additional remediation.
Page 2 of 2 Att. 3 Investigation F8130711 Data Assessment July 2, 2008 Survey Unit F8130711
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4-I 5,000 4,500 4,000 3,500 3,000 2,500 2,000 1,500 1,000 500 2077 0
0 20 40 60 80 100 Percentile Direct Measurements (dpm/lOOcm2) median
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a 4000 0
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