ML090890588
| ML090890588 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 06/18/2008 |
| From: | Andersen D Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097, F8260151 | |
| Download: ML090890588 (20) | |
Text
Rancho Seco Final Status Survey Summary Report June 18, 2008 Turbine Building (+) 0' El., South Floor Survey Unit F8260151 Prepared By: td.*ox_-
- m. Date: o/ig/./12W FSS Engineer Reviewed By:7*' J* - L. UA Date: \ V9-? eq Lead FSS Engineer Approved By: Date:________
Dismantlement erintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8260151, Turbine Building (+) 0' El., South Floor Survey Unit
Description:
Operating History: The reinforced concrete and steel structure contained the turbine-generator and supporting systems. The building contained five 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.
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 in the condenser pit elevation showed a mean gross activity level of 3,077 dpm/100 cm 2 and a maximum value of 24,900 dpm/l 00 cm 2 . Direct measurements on the grade elevation showed a mean gross activity level of 2,035 dpm/100 cm2 and a maximum value of 6,980 dpm/100 cm 2 . Direct measurements on the mezzanine elevation showed a mean gross activity level of 1,566 dpm/100 cm 2 and a maximum value of 2,626 dpm/100 cm 2. Direct measurements on the +40' elevation showed a mean gross activity level of 2,843 dpm/100 cm 2 and a maximum value of 3,615 dpm!100 cm 2. Direct measurements on the building exterior showed a mean gross activity level of 1,984 dpm/100 cm 2 and a maximum value of 10,312 dpm/100 cm 2. Based on the classification procedure (DSIP-0020) and levels' of gross activity reported, the interior of the turbine building was determined to be Class 1, 2, & 3 areas and the exterior was, a Class 3.
During characterization surveys of F8260141 (Turbine Building (+) 0' El., South Floor, Class 2), beta measurements identified activity within a 4-meter by 4-meter area that exceeded the DCGL of 43,000 dpm/100 cm 2. The area was subsequently remediated and reclassified as a Class 1 structure, based on the classification procedure (DSIP-0020). As a result of the reclassification, a new survey package was initiated as F8260151.
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 determined using a random-start, fixed grid pattern and 16 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 F8260151
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F826 Turbine Building (+) 0' El.,
South Floor Survey Unit: 0151 Structure Surface Class: 1 LTP Table 5-4 SU Area (m2): 16 Evaluator: D. Anderson DCGL (dpm/100 cm 2): 43,000 Gross Activity DCGL Area Factor: 14.9 Class 1 Design DCGLemc 640,700 Class 1 (dpm/100 cm 2):
LBGR (dpm/100 cm 2): 25,030 Adjusted Design Sigma (dpm/100 cm 2): 5,990 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): 1.0 Class 1 Scan Area (M2): 16 Scan Coverage (%): 100% Class I 1.645 1.645 Sign P: 0.99865 Calculated Relative Shift: 3 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 I Grid Spacin2 L: 1.0 Class 1 Page 3 of 8 FSS Summary Report F8260151
Survey Results:
A total of 16 direct measurements were made, in F8260151. 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 3,492 to 13,953 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 Activit (dpm/100 cm i
F8260151-CO001BD 1,323 F8260151-CO002BD 1,421 F8260151-CO003BD 1,323 F8260151-CO004BD 1,520 F8260151-CO005BD 1,110 F8260151-C0006BD 1,312 F8260151-CO007BD 1,473 F8260151-CO008BD 1,899 F8260151 -CO009BD 1,567 F8260151-Co01OBD 2,806 F8260151-CO011BD 1,509 F8260151-Co012BD 1,717 F8260151-Co013BD 1,349 F8260151-Co014BD 1,535 F8260151-CO015BD 1,421 F8260151-Co016BD 1,551 Mean: 1,552 Median: 1,491 Standard Deviation: 380 Range: 1,110 - 2,806 Page 4 of 8 FSS Summary Report F8260151
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/l00 cm 2 )
4-F8260151 C0001 SM -0.95 F8260151CO002SM -4.82 F8260151 C0003SM -3.53 F8260151 C0004SM -2.24 F8260151 COOO5SM 0.34 F8260151CO006SM -2.24 F8260151 C0007SM -0.95 F82601 51 C0008SM -2.24 F8260151 C0009SM -2.24 F8260151Co010SM -0.95 F8260151C0011SM 4.22 F8260151Co012SM -4.82 F8260151CO013SM -2.24 F8260151CO014SM -2.24 F8260151Co015SM 0.34 F8260151Co016SM -4.82 Mean: -1.83 Median: -2.24 Standard Deviation: 2.3 Range: -4.82 to 4.22 Page 5 of 8 FSS Summary Report F8260151
Survey Unit Data Assessment:
The survey design required 16 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 F8260151
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): 16 Median (dpm/100 cm 2): 1,491 Mean (dpm/100 cm 2 ): 1,552 Direct Measurement Standard Deviation 380 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 cm 2): 380 Based on samples and backgrounds.
Maximum (dpm/100 cm 2): 2,806 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 16 S+ Value: 16 Critical Value: 11 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 F8260151
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 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. 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 Table 5-6 of the LTP. No direct measurements exceeded the DCGL of 43,000 dpm/100 cm 2 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 F8260151 meets the release criteria of 10CFR20.1402.
Page8 of8 FSS Summary Report F8260151
Attachment 1 Maps June 18, 2008 Survey Unit F8260151
Map F8260151-1, South Turbine Building (+) 0' Elevation 0 1 2 3 4 Class 1 Area DistanceinMeters Area Estimate: 16 sq. meters Page 2 of 5 Att. 1 Maps F8260151
- -~----------------------- - - -
CD NRIII ýIII-J. -- --
.2 n fro inso th ord r 1.2 m E
00 0 2 4 6 I I 12 14 - 1 2 2 CN 02 4 6 60 10 12 14 10 18 20 22 C:)
N Map F8260151-2, South Turbine Building (+) 0 Elevation Class 1 Area 0 0.25 0.5 0.75 1.0 Random Start Location Distance in Meters
CD 0 m 12.6 m 3B 431 0.6 m It 00 o Distance in meters 3 2 2 2 . from SW comer Map F8260151-3, South Turbine Building (+) 0' Elevation Class 1 Area Beta Direct Measurements 0 0.25 0.5 0.75 1.0 F8260151C0001BD to F8260151C0016BD Distance in Meters 1 m by 1 m grid spacing
4i.0m 0
16BS 15BS 14BS 13BS f-I'
.0m 9BS 1OBS 11BS 12BS 2,1 f BBS 7BS 6BS 5BS
.0 m 1BS 2BS 3BS 4BS It' 00 N) 0 _C:o Distance in meters 1-1 3 3 3 3 from SW corner Map F8260151-4, South Turbine Building (+) 0 Elevation Class 1 Area 0 0.25 0.5 0.75 1,0 Beta Scan Measurements Distance in Meters F8260151C0001BS to F8260151C0016BS
Attachment 2 Instrumentation June 18, 2008 Survey Unit F8260151
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No. Model; Serial No. (dpm/100 cm ) 2 (dpm/100 cm2 )
M2350; 149794 43-68/5B; 149103 433 1,033 Tennelec; 0401171 N/A 5.88 dpm a, N/A 11.71 dpm 13 Table 2-2. Investigation Criteria and DCGL Value alue c Parameter d (dpm/100 cm2)
Investigation Criteria - Direct 640,700 Investigation Criteria - Scan 640,700 DCGLw 43,000 DCGLEMc 640,700 Page 2 of 2 Att. 2 Instrumentation F8260151
Attachment 3 Investigation June 18, 2008 Survey Unit F8260151 (none required)
Attachment 4 Data Assessment June 18, 2008
- Survey Unit F8260151
F8260151 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm2 3,000 -
2,500 -
It~
2,000 -
1,500 - 1491 4'-
Im 1,000 -
500-U)1 0
0 20 40 60 80 100 Percentile
- Direct measurements (dpm/lO0cm2) medi an - 75th Percentile 50th Percentile
o F8260151 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpm100cmt 3000 a . a . - . . . . . . . . . . a .- - U - - - - - - - - - - 2692 F" 2500 E
U S20000 E,-
- C - - - - - - -
0
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> 0 rIs wW 500 - .
~413 0
0 0 0 0 000a 0 0 0 0a 0 0 M
r-m N4 mm Mm M
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V mmM r V N WmmIM tt 07 U mw a oa a a a a a a a3 a Ca a 0 a0 0 0 a a a 0 0U U 0U 0U 0U a U U U U U U. U U U U U Measurement Locations L2o Gross Activity - Average - - "+3StDev" - - "-3StDev 0 -: .... : T : 11: .. .T 7 T : TT : " : : . .. . .. . . . .. . ." :
- 1 1* *i ] : ** : : ::: : ::": .. . . .: 1* : 1* L.
F82601 51 Gross Activity Frequency Plot DCGL = 43000 dpm/100cm2 8
(tZ 7 CD 6 5
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1 0
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N" It 00 ON Bins - Upper End Value (dpm/1 00cm2)