ML081620209
| ML081620209 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/08/2008 |
| From: | Ellen Brown Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| F8990351 | |
| Download: ML081620209 (16) | |
Text
Rancho Seco Final Status Survey Summary Report February 26, 2008 Nuclear Service Cooling Water Piping Survey Unit F8990351 Prepared By:
FSS n~gi Reviewed By:
"7ULead F/4S EI Approved By:
Dismantlement SuperintE Date: /2Loo Date:_
4
/1 Date:_______
Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
- F8990351, Survey Unit
Description:
Operating History: This system. was a two-train, redundant system which provided dematerialized cooling water to heat exchangers and coolers associated with components critical to nuclear safety and transferred the heat to the NRW system. This system was designed to be clean. However, the system piping became contaminated due to various primary to secondary system leaks. Operating records and the HSA document several occurrences of minor radioactive contamination associated with this system piping.
Site Characterization: Direct measurements were made of the interior surfaces of the system piping which confirmed the absence of plant-derived radionuclides. Direct measurements of the interior showed a mean gross activity level of -59 dpm/100 cm2 and a maximum value of 174 dpm/l 00 cm2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the system was determined to be a Class 3 system.
HSA Events: ODR-870582.
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 spaced at 15cm intervals and 2.6 m2 were scanned for approximately 7%
coverage. 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 7 FSS Summary Report F8990351
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area:
F899
.Survey Unit:
Class:
SU Area (m2):
Evaluator:
DCGL (dpm/100 cm'):
Area Factor:
Design DCGLemc (dpm/100 cm 2):
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 (%):
Sign P:
Calculated Relative Shift:
Relative Shift Used:
N-Value:
Design N-Value + 20%:
Design Min Samples N:
Grid SpacinE L:
0351 3
35.4 Erin L. Brown 100000 N/A N/A 50000 125 0.05 0.05 Cs-137 N/A 2.6 7%
1.645 1.645 0.99865 628 3
11 14 14 N/A Nuclear Service Cooling Water Piping Pipe Internal Surface LTP Table 5-4 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 5-5 Class 3 Class 3 Page 3 of 7 FSS Summary Report F8990351
Survey Results:
A total of 14 direct measurements were made in F899035 1. 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 6,101 to 10,249 dpm/1 00 cm 2, based. on the pipe detector efficiency.
Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/100 cm F8990351-MOO01GI F8990351-MOO02GI F8990351-MOO03GI F8990351-MOO04GI F8990351-MOO05GI F8990351-MOO06GI F8990351-MOO07GI F8990351-MOO08GI F8990351-MOO09GI F8990351-MOOOGI F8990351-MOO11GI F8990351-MOO12GI F8990351-MOO13GI F8990351-MOO14GI Mean:
Median:
Standard Deviation:
Rancqe:
6964 6101 6114 6570 7452 8566 8934 8966 9065 9049 8967 9086 9526 10249 8258 8950 1345 6101-10249 Page 4 of 7 FSS Summary Report F8990351
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. Since both values of sigma resulted in a relative shift greater than three (3), no additional samples were required.
Page 5 of 7 FSS Summary Report F8990351
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm 2):
Ambient Background Used (dpm/100 cm):
Actual Direct Measurements (N):
Median (dpm/100 cm2):
Mean (dpm/100 cm 2):
Direct Measurement Standard Deviation (dprr1O00 cm 2):
Total Standard Deviation (dpm/100 cm 2):
Maximum (dpm/100 cm2):
Material Type:
Sign Test Final N Value:
S+ Value:
Critical Value:
Sufficient Samples Collected:
Maximum Value < DCGL:
Median Value < DCGL:
Mean Value < DCGL:
Maximum Value < DCGLemc:
Total Standard Deviation <= Sigma:
Pass the Sign Test?
Reject the Null Hypothesis?
Does the Survey Unit Pass All Criteria?
N/A N/A 14 8950 8258 1345 1345 10249 N/A 14 14 10
.Yes Yes Yes Yes N/A Investigate Yes Yes Investigate Average Ambient BKG = 0 Based on samples and backgrounds.
Background Subtract Not Applied Class 3 No additional samples required The SU passes Page 6 of 7 FSS Summary Report F8990351
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 (i.e. the survey unit average activity 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 withthat 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.
==
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 100000 dpm/100 cm 2 or the grout limit of 21,000 dpm!O00 cm 2. 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 F8990351 meets the release criteria of IOCFR20.1402.
Page 7 of 7 FSS Summary Report F8990351 Maps February 26, 2008 Survey Unit F8990351
0 I
KEY PLAN LEGEN~
R~EK4;WNG UNDERRUND*
R-- MO I* P C0ONTM -MEf 00 P1P?4 SUM~WAY MZE LEN2j AME i ko 75 LF ~33SM NUCLEAR SERVIC:E; WATER
-UNDERGROUND PIPING F,8990351 1M S
I OF 1 RC RAYW4 Instrumentation February 26, 2008 Survey Unit F8990351
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; 189081 44-162; 206935 2590 N/A Table 2-2.. Investigation Criteria and DCGL Parameter Value (dpm/100 cm2)
Investigation Criteria - Direct 50000 Investigation Criteria - Scan N/A DCGLw 100000 DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8990351 Investigation February 26, 2008 Survey Unit F8990351 (none required)
Data Assessment February 26, 2008 Survey Unit F8990351
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F8990351 Gross Activity Sample Results Quantile Plot DCGL = 100000 dpm/1 00cm2
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8950 0
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-median
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F8990351 Gross Activity Sample Results Scatter Plot DCGL = 100000 dpml1OOcm 2 u3 O0 0'
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