ML090900732
| ML090900732 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 10/29/2008 |
| From: | Ellen Brown Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097 | |
| Download: ML090900732 (18) | |
Text
Rancho Seco Final Status Survey Summary Report October 29, 2008 HP Turbine Pedestal Drains Survey Unit F8990074 Prepared By:__ ___._ _ __ Date: /10/9/Zo FSS Engineer Reviewed By:__ _ _ Date: to Lead FSS Engineer Approved By: 7 Date: a i Dismantlement Supeintendent, Radiological
.FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8990074, HP Turbine Pedestal Drains Survey Unit
Description:
Operating History: This system collected clean water leakage and condensate from the turbine and routed it to the drain tank. This system was contaminated by radioactive system leakage into steam, feed and cooling water systems. Operating records and the HSA document occurrences of radioactive contamination associated with this system piping.
Site Characterization: Direct measurements were made of the interior surfaces of the system piping which confirmed the presence of plant-derived radionuclides. Direct 2
measurements of the interior showed a mean gross activity level of 56,208 dpmr/100 cm and a maximum value of 680,000 dpm/100 Cm2 . Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the system was determined to be a Class 1 system.
HSA Events: ODR-800111, 871122.
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 8 ml were scanned for 100% 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 8 FSS Summary Report F8990074
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F899 HP Turbine Pedestal Drains Survey Unit: 0074 Piping Class: 1 LTP Table 5-D SU Area (m2): 8 Evaluator: Erin L. Brown DCGL (dpm/100 cm2): 100000 Gross Activity DCGL Area Factor: 1 Class 1 Design DCGLemc 100000 Class 1 2
(dpm/100 cm ):
LBGR (dpm/100 cm2): 50000 Default = 50% DCGL Design Sigma (dprn/100 cm2): 23464 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): N/A Embedded Pipe Scan Area (m2): 8 Scan Coverage (%): 100% Class 1 Zl_, : 1.645 Z1.* : 1.645 Sign P: 0.97725 Calculated Relative Shift: 2.2 Relative Shift Used: 2.2 Uses 3.0 if Relative Shift is
>3 N-Value: 12 Design N-Value + 20%: 15 NUREG-1575 Table 5-5 Design Min Samples N: 15 Class I Grid Spacing L: 0.7 Class 1 Page 3 of 8 FSS Summary Report F8990074
Survey Results:
A total of 44 direct measurements were made in F8990074. 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 measurements indicated areas of elevated activity.
Survey activity ranged from 3531 to 6926 dpm/100 cm2 , based on the pipe detector efficiency.
Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/100 cm)
F8990074-MOO01 GI 5619 F8990074-MOO02GI 5393 F8990074-MOO03GI 5723 F8990074-MOO04GI 6152 F8990074-MOO05GI 6570 F8990074-MOO06GI 6655 F8990074-MOO07GI 6637 F8990074-MOO08GI 6565 F8990074-MOO09GI 6744 F8990074-MOOIOGI 6695 F8990074-MOO11GI 6851 F8990074-MOO12GI 6852 F8990074-MOO13GI 6883 F8990074-MOO14GI 6875 F8990074-MOO15GI 6926 F8990074-MOO16GI 6781 F8990074-MOO17GI 6883 F8990074-MOO18GI 6916 F8990074-MOO19GI 6853 F8990074-MOO20GI 6756 F8990074-MOO21GI 6572 F8990074-M0022GI 3531 F8990074-M0023GI 3909 F8990074-M0024GI 3931 F8990074-M0025GI 4244 F8990074-M0026GI 4335 F8990074-M0027GI 4370 F8990074-M0028GI 4462 F8990074-M0029GI 4367 F8990074-MOO30GI 4374 F8990074-M0031 GI 4452 F8990074-M0032GI 4362 F8990074-M0033GI 4429 F8990074-M0034GI 4523
.F8990074-M0035GI 4303 F8990074-M0036GI 3666 F8990074-M0037GI 3912 F8990074-M0038GI 3801 F8990074-M0039GI 3566 F8990074-MOO40GI 3848 Page 4 of 8 FSS Summary Report F8990074
F8990074-M0043GI 6253 F8990074-M0044GI 5935 F8990074-M0045GI 5772 F8990074-M0046GI 5934 Mean: 5459 Median: 5747 Standard Deviation: 1246 Range: 3531 -6926 Page 5 of 8 FSS Summary Report F8990074
Survey Unit Data Assessment:
The survey design required 44 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 F8990074
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm2): N/A Ambient Background Used (dpm/100 cm 2): N/A Average Ambient BKG = 0 Actual Direct Measurements (N): 44 Median (dpm/100 cm 2): 5747 Mean (dpm/100 cm 2): 5459 Direct Measurement Standard Deviation 1246 2
(dpm/100 cm ):
Total Standard Deviation (dpm/100 cm 2): 1246 Based on samples and backgrounds.
Maximum (dpm/100 cm 2 ): 6926 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 44 S+ Value: 44 Critical Value: 27 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 F8990074
Survey Unit Investigations and Results:
No investigations were required 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 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 dataused for survey design. No potential areas of elevated activity were detected. 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 the LTP for pipe surveys. No direct measurements exceeded the DCGL of 100000 dpm/100 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 F8990074 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F8990074
Attachment 1 Maps October 29, 2008 Survey Unit F8990074
Map F8990074-2, HP Turbine Pedestal Drains Hub (+ 0' El.) is at 40' El.
Page 2 of 3 Att. 1 Maps F8990074
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- 1 i[1 ---- -' 7 Location of Turbine Building inside the Industrial Area 00 I Map F8990074-1, Turbine Building Location of Turbine Building at Rancho Seco site
'Elevation
Attachment 2 Instrumentation October 29, 2008 Survey Unit F8990074
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; 142512 44-162; L206935 2590 N/A Table 2-2. Investigation Criteria and DCGL Value Parameter (dprn1lO cm 2 )
Investigation Criteria - Direct 100000 Investigation Criteria - Scan N/A DCGLw 100000 DCGLEMC 100000 Page 2 of 2 Att. 2 Instrumentation F8990074
Attachment 3 Investigation October 29, 2008 Survey Unit F8990074 (none required)
Attachment 4 Data Assessment October 29, 2008 Survey Unit F8990074
F8990074 Gross Activity Sample Results Quantile Plot 2
DCGL = 100000 dpm/1OOcm 8,000 7,000 6,000 5747 5,000 I 4,000 3 3,000 2,000 1,000 0
0 20 40 60 80 100 Percentile 00
- Direct Measurements (dpm/100cm2) -median - - -75th Percentile . 50th Percentile,
--A
0 0
F8990074 Gross Activity Sample Results Scatter Plot DCGL = 100000 dpm/100cm= 2 10000 Cn 9000
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m m - - - m *- *- u M - - - m 919f CD 8000 E
7000 000000000000000()00 0 0 0 6000 545Ca E
5000 o00000o0o00o C) 4000 00 0 00oo 3000 2000 m~ ~~~~,-, - - -m -m -- -l -l -I a-I m
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- n-, ,- - -m -m 1000 0
C) 0oo 00 00 0 0 0000 000Q00 00 0"0 00000 -00 Measurement Locations Fo Gross Activity - Average - - "+3StDev" - - "-3StDev"j
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F8990074 Gross Activity Frequency Plot DCGL - 100000 dpm/1 00crrmf 14-,
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