ML090850556
| ML090850556 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 09/08/2008 |
| From: | Donna Anderson Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097 | |
| Download: ML090850556 (25) | |
Text
Rancho Seco Final Status Survey Summary Report September 8, 2008 Turbine Building Exterior Walls, (+) 0' El. to (+) 40' El.
Survey Unit F8260302 Prepared By: c:* _ Date: q/18/,/og FSS Engineer Reviewed By: \2 Date: \\4u) 0oS Lead FSS Engineer Approved By:_ _________ Date: '-
7 Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8260302, Turbine Building Exterior Walls, (+/-) 0' El. to (+) 40' El.
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 mea-urements confirmed the presence of plant-derived radionuclides. Direct measurements i~n the condenser pit elevation showed a mean gross activity level of 3,077 dpm/100 cm2 and a maximum value of 24,900 dpm/100 cm 2 . Direct measurements on the grade elevation showed a mean gross activity level of 2,035 dpm/100 cm 2 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 cm2 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.
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. I)irect measurement locations were randomly determined and 903 m2 were scanned for approximately 57%
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 F8260302
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F826 Turbine Building Exterior Walls, (+) 0' El. to (+) 40' El.
Survey Unit: 0302 Structure Surface Class: 3 LTP Table 5-4 SU Area (m2): 1,596 Evaluator: D. Anderson 2
DCGL (dpm/100 CM ): 43,000 Gross Activity DCGL Area Factor: N/A Class 3 Design DCGLemc N/A Class 3 2
(dpm/100 cm ):
LBGR (dpm/100 cm 2 ): 37,831 Adjusted Design Sigma (dpm/100 CMr): 1,723 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): N/A Class 3 Scan Area (M2): 903 Scan Coverage (%): 57% Class 3 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 3 Grid Spacing L: N/A Class 3 Page 3 of 8 FSS Summary Report F8260302
Survey Results:
A total of 14 direct measurements were made in F8260302. 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. The gamma activity ranged from < 974 dpm/100 cm 2 Co-60 and < 953 dpm/100 cm 2 to 971 dpm/100 cm 2 Cs-137. 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 .
Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/100 cm-)
F8260302-MOO01 BD 1,015 F8260302-MOO02BD 640 F8260302-MOO03BD 655 F8260302-MOO04BD 809 F8260302-MOO05BD 621 F8260302-MOO06BD 671 F8260302-MOO07BD 769 F8260302-MOO08BD 1,138 F8260302-MOO09BD 1,504 F8260302-MOOOBD 1,129 F8260302-MOO 1 BD 1,477 F8260302-MOO12BD 1,972 F8260302-MOO13BD 1,935 F8260302-MOO14BD 1,830 Mean: 1,155 Median: 1,072 Standard Deviation: 502 Range: 621 -1,972 Page 4 of 8 PFSS Summary Report F8260302
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2 )
F8260302M0001 SM -0.95 F8260302M0002SM -3.53 F8260302M0003SM 0.34 F8260302M0004SM -0.95 F8260302M0005SM 2.93 F8260302M0006SM -3.53 F8260302M0007SM -3.53 F8260302M0008SM -0.95 F8260302M0009SM -2.24 F8260302M0010SM -2.24 F8260302M0011 SM -3.53 F8260302M0012SM -6.11 F8260302M0013SM -2.24 F8260302M0014SM -0.95 Mean: -1.96 Median: -2.24 Standard Deviation: 2.16 Ranqe: -6.11 to 2.93 Page 5 of 8 FSS Summary Report F8260302
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 less than the design standard deviation so no additional samples were required.
Page 6 of 8 FSS Summary Report F8260302
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/IO0 cm): N/A Ambient Background Used (dpn/100 cm 2): N/A Average Ambient BKG = 0 Actual Direct Measurements (N): 14 Median (dpm/100 cm 2): 1,072 Mean (dprm/100 cm 2): 1,155 Direct Measurement Standard Deviation 502 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 2 cm ): 502 Based on samples and backgrounds.
Maximum (dpm/100 cm 2): 1,972 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 14 S+ Value: 14 Critical Value: 10 Sufficient Samples Collected: Yes Maximum Value < DCGL: Yes Median Value < DCGL: Yes Mean Value < DCGL: Yes Maximum Value < DCGLemc: N/A Class 3 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 F8260302.
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 3 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 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 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 F8260302 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F8260302
Attachment 1 Maps September 8, 2008 Survey Unit F8260302
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- lr C)A
'** I.:*"Location of Turbine Build ing Lj- ""- '"inside the Industrial ArE9a Turbine Building East Exterior Wall I
I Area Estimate: 154 sq. meters N) Turbine Building South Exterior Wall C I Area Estimate: 398 sq. meters 0 2 -4 6 8 Map F8260302-1, Turbine Building Exterior Distance in Meters East and South Exterior Walls Area Estimate: 552 square meters
CID 0o Turbine Building North Exterior Wall Area Estimate: 454 sq. meters 0 2 4 6 8 Distance in Meters 00
~i* Turbine Building West Exterior Wall C_ Area Estimate: 590 sq. meters Uj 0 2 4 6 8 Distance in Meters Map F8260302-2, Turbine Building Exterior North and West Exterior Walls Area Estimate: 1,044 square meters
0 00 m 0 4 6 DitneinMtr 15 45 50 55 65 70 Map F8260302-3, Turbine Building Exterior Walls Random Sample Locations for Beta Direct Measurements (Class 3)
0.3mr C>.
Turbine Building North Exterior Wall 0 *2 4 6 8 Distano in Metems It 00 0 2 4 6 8 C) Distance in Metras Map F8260302-4, Turbine Building North and West Exterior Walls Beta Direct Measurements F8260302M0001BD to F8260302M0004BD and F8260302M0011BD to F8260302M0014BD
CN 18 9 BD I~
.0.3 m 0
C) 4m 3m ILL L~i~iXjiOBD'-
-r2mr E
Turbine Building East Exterior Wall
-- V1777ZA C) [ý MF5-B-DI K 14 m 178 U[ 0/ X 01BD.I2 E
IfO 5mn 6801, 00 wo ON Turbine Building South Exterior Wall X7
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ýj Map F8260302-5, Turbine Building East and South Exterior Walls 0 2 4 6 8 Beta Direct Measurements Distance in Meters F8260302M0005BD to F8260302M0010BD
Distance in meters from Turbine Building (+) 40' El.
Map F8260302-6, Turbine Building East Exterior Wall ISOCS! Gamma Scan Measurements F8260302M0001 GS to F8260302M0007GS 12.57 sq. meter field of view Total Scan Area: 79 sq. meters 0 1 2 3 4 Distance in Meters Page 7 of 10 Att. I Maps F8260302
CD O 00!
0 Distance in meters from Turbine Building
(+) 0' El.
I/
2.0 rm - 19GS 202IG2GS 24GS 25GS zW
- 3 33 Oomm 3 6 3
i :
3 3 3 6
3 3 3 4
ý. :i"--- 3 3 3 00 3c o-, , 5@ ! P3 Map F8260302-7, Turbine Building S3 3 3 North Exterior Wall ISOCS Gamma Scan Measurements 0 2 4 6 8 8
F8260302M0008GS to F8260302M0025GS oistance in M 12.57 sq. meter field of view Total Scan Area: 221 sq. meters
0 C) t - Map F82( ujuz-UL, iurDine uimaing 0 E West ExtEerior Wall
- H ISOCS Gamma Scan Measurements
- F826030, 2M0026GS to F8260302M0029GS, v2 3 F826030' 2M0033GS, and i- rn D F826030, 2M0039GS to F8260302M0045GS 7 12.57 sq. meter field of view F826030, 2M0030GS to F8260302M0032GS CF826030, 2M0034GS to F8260302M0038GS, and F826030, 2M0046GS to F8260302M0050GS 19.6 sq. nrneter field of view Total Scain Area: 377 sq. meters I. I0
-a 54 - Distance from in meters Turbine Building Distance from in meters Turbine Building - P W iN1 R PD PgKio 3 3 b3 W-4 M 11 "
I,.) 3 3 3 3 3 3 Northwest corner Southwest corner 3 3 3 3 3 3 3 0 2 4 6 8 Distanc~e anMeters
CtC S-~
33 MCD 00 9.4 m 0
5.9 mr 2.3 mn- . S IS 52G-4GI5G I3G 1 1- . I- 56ý1
~j~
o Fn 3 5C5 Map F8260302-9, Turbine Building South Exterior Wall 0 2. 4 6 8 ISOCS Gamma Scan Measurements Distance in Meters F8260302M0051GS to F8260302M0068GS 12.57 sq. meter field of view Total Scan Area: 226 sq. meters
Attachment 2 Instrumentation September 8, 2008 Survey Unit F8260302
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; 203486 43-68B; 161400 257 612 Tennelec; 0401171 N/A 5.88 dpm a N/A 11.71 dpm _
Instrument Detector Model No. Detector IDC Serial No.
2 isocs N/A 2983947 Concrete 953 dpm/100 Concrete-- 974 cm 2Cs-137, dpm!100 cm Co-60 Table 2-2. Investigation Criteria and DCGL Value Parameter dp lue (dpm/1 cm 2 )
00 c2 Investigation Criteria - Direct 21,500 Investigation Criteria - Scan (ISOCS average Cs-137 activity 2,300 for 12.5 m 2 field of view)
DCGLw 43,000 DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8260302
Attachment 3 Investigation September 8, 2008 Survey Unit F8260302 (none required)
Attachment 4 Data Assessment September 8, 2008 Survey Unit F8260302
CD, F8260302 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm2 2,500 2,000 1,500 I:1,000 1072 500 0
0 20 40 60 80 100 It1 Percentile 00 tQ
- Direct Measurements (dpm/lOOcm2) -median - - -75th Percentile . 50th Percentile
('3 C
F8260302 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpml100cm2 3000
- - - -- - - ----------- m - - ------ 2562 2600 E
- q. 2000 0 0 0 C
00
> 'ooo1500 E 0 1155 a~1000 00 0 0 0 0
> ?500
-> 0
-500 - - S- - - - - - - - - -
.--.-- - I 1 -352
-1000 CN o to to ao a M ao a a aO aO a a a C,)
Uj O0
- V-r- N C' Vt to 10 w CD N.
N 0w w W 0 C r N 0 0 Cd, a a a 0 a 0 a Measurement Locations Foo 1 o Gross Activity - Average - - "+3StDev" - - "-3StDev" ON 0,
('
0o
F8260302 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm2 5
4 3
U-L0 00 2
I C%
0 N N N N N N N N 0 C?) (0 0)
Bins - Upper End Value (dprn1 00cm2)