ML081580595
| ML081580595 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/08/2008 |
| From: | Ellen Brown Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| F8990321 | |
| Download: ML081580595 (19) | |
Text
Rancho Seco Final Status Survey Summary Report March 10, 2008 Nitrogen Gas System Piping Survey Unit F8990321 Prepared By: 6,Z 12 /Z_ Date: ,,/11106 FSS E" er Reviewed By:__________ Date: ý,/,
Lead Fg 1 Engineer Approved By: Date:_______
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8990321, Nitrogen Gas System Piping Survey Unit
Description:
Operating History: This system distributed nitrogen gas to various primary tanks and systems to maintain an inert cover gas. This system was designed to be clean but had become contaminated by operational events that contaminated the piping. Operating records and the HSA document several 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 radioactivity above background levels.
Direct measurements of the interior showed a mean gross activity level of 19,096 dpm/100 cm 2 and a maximum value of 33,208 dpm/100 cm2 . Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the system was determined to be a Class 2 system.
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 spaced at 15cm and 2.6 m2 were scanned for approximately 11%
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 9 FSS Summary Report F8990321
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F899 Nitrogen Gas System Piping Survey Unit: 0321 Structure Surface Class: 2 LTP Table 5-4 SU Area (m2): 24.7 Evaluator: Erin L. Brown DCGL (dpm/100 cm 2): 100000 Gross Activity DCGL Area Factor: N/A Class 2 Design DCGLemc N/A Class 2 2
(dpm/100 cm ):
LBGR (dpm/100 cm 2): 50000 Default 50% DCGL Design Sigma (dpm/100 cm2 ): 9677 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (M2): N/A Class 2 Scan Area (m2): 2.6 Scan Coverage (%): 11% Class 2 1.645 1.645 Sign P: 0.99865 Calculated Relative Shift: 5.2 Relative Shift Used: 3 Uses 3.0 if Relative Shift is
>3 N-Value: 11 Design N-Value + 20%: 14 NUREG-1575 Table 5-5 Design Min Samples N: 14 Class 2 Grid Spacing L: N/A Class 2 Page 3 of 9 FSS Summary Report F8990321
Survey Results:
A total of 109 direct measurements were made in F8990321. 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.
Measurements ranged from 2384 to 4376 dpm/100 cm 2, based on the pipe detector efficiency.
Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/100 cm;)
F8990321-MOOOIGI 2722 F8990321-MOOO2GI 2645 F8990321-MOO03GI 2476 F8990321-MOO04GI 3280 F8990321-MOO05GI 3194 F8990321-MOO06GI 3584 F8990321-MOO07GI 3589 F8990321-MOO08GI 3579 F8990321-MOO09GI 3666 F8990321-MOOlOGI 3728 F8990321-MOO11GI 3714 F8990321-MOO12GI 3213 F8990321-MOO13GI 3064 F8990321-MOO14GI 3329 F8990321-MOO15GI 3603 F8990321-MOO16GI 3430 F8990321-MOO17GI 3155 F8990321-MOO18GI 3232 F8990321-MOO19GI 3141 F8990321-MOO20GI 2717 F8990321-M0021GI 2726 F8990321-M0022GI 2476 F8990321-M0023GI 2779 F8990321-M0024GI 2611 F8990321-M0025GI 2616 F8990321-M0026GI 2413 F8990321-M0027GI 2693 F8990321-M0028GI 3015 F8990321-M0029GI 3434 F8990321-MOO30GI 3646 F8990321-MOO31GI 3242 F8990321-M0032GI 3401.
F8990321-M0033GI 3613 F8990321-M0034GI 3391 F8990321-M0035GI 3565 F8990321-M0036GI 3656 F8990321-M0037GI 3430 F8990321-M0038GI 3107 F8990321-M0039GI 2601 F8990321-MOO40GI 2461 Page 4 of 9 FSS Summary Report F8990321
F8990321-MOO41GI 2384 F8990321-M0042GI 2567 F8990321-M0043GI 2958 F8990321-M0044GI 2948 F8990321-M0045GI 3382 F8990321-M0046GI 3536 F8990321-M0047GI 3608 F8990321-M0048GI 3603 F8990321-M0049GI 3223 F8990321-MOO50GI 3377 F8990321-MOO51GI 3319 F8990321-M0052GI 3579 F8990321-M0053GI 3319 F8990321-M0054GI 3757 F8990321-M0055GI 3637 F8990321-M0056GI 3738 F8990321-M0057GI 3743 F8990321-M0058GI 3560 F8990321-M0059GI 3521 F8990321-MOO60GI 3449 F8990321-M0061GI 3690 F8990321-M0062GI 3406 F8990321 -M0063GI 3487 F8990321-M0064GI 3593 F8990321-M0065GI 3796 F8990321-M0066GI 3743 F8990321-M0067GI 4090 F8990321-M0068GI 3781 F8990321-M0069GI 3656 F8990321-MOO70GI 3309 F8990321-MOO71GI 2972 F8990321-M0072GI 3184 F8990321-MOO73GI 3434 F8990321-M0074GI 3651 F8990321-M0075GI 3497 F8990321-M0076GI 3724 F8990321-M0077GI 3685 F8990321-M0078GI 3849 F8990321-M0079GI 3897 F8990321-MOO80GI 3540 F8990321-M0081GI 3579 F8990321-M0082GI 3762 F8990321-MOO83GI 4041 F8990321-M0084GI 3810 F8990321-M0085GI 3897 F8990321-M0086GI 3945 F8990321-M0087GI 3815 F8990321-MOO8GI 4022 F8990321-M0089GI 3762 F8990321-MOO90GI 3776 F8990321-MOO91GI 3492 F8990321-M0092GI 3907 F8990321-M0093GI 3950 F8990321-M0094GI 3632 F8990321-M0095GI 3699 F8990321-M0096GI 3719 Page 5 of 9 FSS Summary Report F8990321
F8990321-M0097G3 3656 F8990321-M0098GI 3762 F8990321-M0099GI 3719 F8990321-MO100GI 3613 F8990321-MO101GI 3473 F8990321-MO102GI .4092 F899,0321-MO103GI 3577 F899ý0321-MO104GI 3725 F899,0321-MO105GI 4089 F899'0321-MO106GI 3610 F899'0321-MO107GI 4019 F899.0321-MO108GI 3748 F8990321-MO109GI 4376 Mean: 3444 Median: 3579 Standard Deviation: 430 Rangle: 2384-4376 Range: 2384 - 4376 Page 6 of 9 FSS Summary Report F8990321
Survey Unit Data Assessment:
The survey design required 109 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 7 of 9 FSS Summary Report F8990321
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/O00 cm 2): N/A Ambient Background Used (dpn/100 cm'): N/A Average Ambient BKG 0 Actual Direct Measurements (N): 109 Median (dpm/100 cm 2): 3579 Mean (dpm/100 cm 2): 3444 Direct Measurement Standard Deviation 430 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 cm 2 ): 430 Based on samples and backgrounds.
2 Maximum (dpm/100 cm ): 4376 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 109 S+ Value: 109 Critical Value: 63 Sufficient Samples Collected: Yes Maximum Value < DCGL: Yes Median Value < DCGL: Yes Mean Value < DCGL: Yes Maximum Value < DCGLemc: N/A Class 2 Total Standard Deviation <= Sigma: Yes Pass the Sign Test? Yes Reject the Null Hypothesis?. Yes Does the Survey Unit Pass All Criteria? Yes Page 8 of 9 FSS Summary Report F8990321
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), the ALARA criterion has been met.
Changes in Initial Survey Unit Assumptions:
The survey unit was designed as a Class 2 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 2 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 dpmrr100 cm 2 or the grout limit of 21000dpm/100cm . 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 F8990321 meets the release criteria of 10CFR20.1402.
Page 9 of 9 FSS Summary Report F8990321
Attachment 1 Maps March 10, 2008 Survey Unit F8990321
0 SCALE HUM-~
KEY PLAN
-o}
Liii 00 LEGEN .
L,.J YARD PIPING C:)
UN-DEROUNO PIING REI.MNS UNDERGROUND PIPING REMOVED Ii o SACRAMIENTO. MUNICIPAL UTUTY DISTRICT BELOW GRADE NITROGEN GAS SYSTEM F8990321 -M 1 FlLi AMO,2 SHEET I of I RO PAYMOND
0 94 TUR90l4E UDOG SCALE KEY PLAN TI I
E.D.P. EL. 29'-16' WLASS 6 UBRA"Y CLAS 2 00
- MU LLEGEND T & R- BUILDING PIPHG REIAANS EIL o8'-O0" FLOOR
-- - PPING PUEI1ZD NITROGEN .GAS SYSTEM WRACMENTO MUNICIPAL UTILITY DiSTRUC F8990321. -M2 SHEET I of I RO RAYMOND
Attachment 2 Instrumentation March 10, 2008 Survey Unit F8990321
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; 142514 pipemon; B821Z 4680, N/A, M2350; 203484 44-159;215855 5250 N/A Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2)
Investigation Criteria - Direct 50000
'Investigation Criteria - Scan. N/A DCGLw 100000 DCGLEMc N/A Page 2 of 2 Att. 2 Instrumentation F8990321
Attachment 3 Investigation March 10, 2008 Survey Unit F8990321 (none required)
Attachment 4 Data Assessment March 10, 2008 Survey Unit F8990321
F8990321 Gross Activity Sample Results Quantile Plot DCGL = 100000 dpm/1 00cm 2 5,000 4,500 4,000 S,50 3579
- 2,5000 500 , -j2I 0 20 40 60 80 100 Percentile
\0
- Direct Measurements (dpm/100cm2) - median - - - 75th Percentile - -- - 50th Percentile
WV CfQ CD
.uJ 0
F8990321 Gross Activity Sample Results Scatter Plot A 2 DCGL = 100000 dpmlO10c m 5000 -
4735 4500 -
tg 4000- 000 0 00 3500- ,o ozd-P 0 o 0 OcP 0 4--"
0 oC0 ~ 00 3444 A 0T 0 0 00 C 3000- CO 0 E bO $0 00 5a2500 - o 09oI I Ca
""2000 - 1 2153
$ 1500 -
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Measurement Locations 00 0 .....
.r Gross ~Activity s........ t ...........-.
.. t - Average..... . ......-
"+3StDev -. a -.......
"-3StDev"I
0" F8990321 Gross Activity Frequency Plot DCGL = 100000 dpm/1 00crm 2 25 24 23 22 21
-D 20 0M 0-* 19 C 18 17 2ID 16 15 LL 14 C 13 12 0 11 0b
.. ) 10 9
cn 8 7
6 5
4 3
2 1
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DO Bins - Upper End Value (dpm/1 00cm2)