ML090850552
| ML090850552 | |
| 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: ML090850552 (26) | |
Text
Rancho Seco Final Status Survey Summary Report September 8, 2008 Turbine Building Interior Walls, (+) 0' El. to (+).40' El. and Mezzanine Grating Survey Unit F8260201 Prepared By: "
- a o'- Date: q___ _._8_
FSS Engineer Reviewed By: "A -ji j1M 2 ate: t 0
-OS Lead FSS Engineer Approved By: I? Date: Z- 7 7 '
DismantlementIDtSv]perintendent, R Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8260201, Turbine Building Interior Walls, (+) 0' El. to (+) 40' El. and Mezzanine Grating 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/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 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 cm2 . 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. Direct measurement locations were randomly determined and 341 m 2 were scanned for approximately 19%
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 F8260201
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F826 Turbine Building Interior Walls, (+) 0' El. to (+) 40' El. and Mezzanine Grating Survey Unit: 0201 Structure Surface Class: 3 LTP Table 5-4 SU Area (m2): 1,776 Evaluator: D. Anderson DCGL (dpm/100 cm 2 ): 43,000 Gross Activity DCGL Area Factor: N/A Class 3 Design DCGLemc N/A Class 3 (dpm/100 cm 2 ):
LBGR (dpm/100 cm 2 ): 39,052 Adjusted Design Sigma (dpm/100 cm 2): 1,316 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): N/A Class 3 Scan Area (m2): 341 Scan Coverage (%): 19%' Class 3 ZI-P : 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 x v L: N/A Class 3 Page 3 of 8 FSS Summary Report F8260201
Survey Results:
A total of 14 direct measurements were made in F8260201. 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 < 619 dpm/100 cm 2 Co-60 and < 903 dpm/100 cm 2 to 507 dpm/100 cm2 Cs-137. Beta scan activity ranged from 4 759 to 12 806 dpm/l100 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
F8260201-MO001BD 880 F8260201-MOO02BD 757 F8260201-MOO03BD 2,325 F8260201-MOO04BD 618 F8260201-MOO05BD 2,111 F8260201-MOO06BD 1,077 F8260201-MOO07BD 649 F8260201-MOO08BD 551 F8260201 -MOO09BD 578 F8260201-MOOOBD 584 F8260201 -MO01 I BD 551 F8260201-MOO12BD 624 F8260201-MOO13BD 643 F8260201-MOO14BD 594 Mean: 896 Median: 634 Standard Deviation: 580 Range: 551 -2,325 Page 4 of 8 FSS Summary Report F8260201
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)
F8260201MOO01SM -4.82 F8260201MOO02SM -0.95 F8260201MOO03SM -3.53 F8260201 M0004SM -2.24 F8260201 M0005SM -2.24 F8260201 M0006SM -3.53 F8260201 M0007SM -3.53 F8260201 M0008SM -0.95 F8260201 M0009SM -4.82 F8260201M0010SM -4.82 F8260201 M001 I SM -2.24 F8260201M0012SM -2.24 F8260201M0013SM -3.53
.F8260201MOO14SM -3.53 Mean: -3.07 Median: -3.53 Standard Deviation: 1.3 Range: -4.82 to -0.95 Page 5 of 8 FSS Summary Report F8260201
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 F8260201
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/ O0 cm 2): N/A Ambient Background Used (dpm/100 cm 2 ): N/A Average Ambient BKG = 0 Actual Direct Measurements (N): 14 Median (dpm/100 cm 2 ): 634 Mean (dpm/100 cm 2 ): .896 Direct Measurement Standard Deviation 580 2
(dpm/100 cm ):
Total Standard Deviation (dpm/100 2 cm ): 580 Based on samples and backgrounds.
Maximum (dpm/100 cm 2 ): 2,325 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 F8260201
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 thatthe survey unit satisfied the release criteria and that the data quality objectives were met.
It is concluded that survey unit F8260201 meets the release criteria of 10CFR20.1402.
Page 8'of 8 FSS Summary Report F8260201
Attachment 1 Maps September 8, 2008 Survey Unit F8260201
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Location of Turbine Building inside the Industrial Area Turbine Building East Interior Wall Area Estimate: 154 sq. meters 00 Turbine Building South Interior Wall Area Estimate: 398 sq. meters C) 0 2 4 6 8 Map F8260201-1, Turbine Building Interior Distance in Meters East and South Interior Walls Area Estimate: 552 square meters
0 Turbine Building North Interior Wall Area Estimate: 454 sq. meters 0 2 4 6 8 Distance in Meters Ct)
Turbine Building West Interior Wall Area Estimate: 590 sq. meters 0 2 4 6 8 Distance in Meters Map F8260201-2, Turbine Building Exterior North and West Interior Walls Area Estimate: 1,044 square meters
2 3 4 6 7 9 10 11 12 13 0
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_ I r P 000 23'4" 17' 0" 20'4" 18'4" 18' 10.5" 18'10.5" 18'4" 23' 4" 23'4" 23' 4" 16'11" ON N
0 2 4 a Map F8260201-3, Turbine Building (+) 20' El.
Distance in Meters Deck at Mezzanine Level Area Estimate: 180 square meters
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-L 40 45 50 55 60 65 70 Map F8260201-4, Turbine Building (+) 0' to (+) 40' El. Interior Walls &
Mezzanine Level Grating
(D C) 5 9
2 Turbine Building East Interior Wall Beta Direct Measurements F8260201M0001BD to F8260201M0002BD, and F8260201M0006BD 00 Turbine Building South Interior Wall Beta Direct Measurements F8260201M0004BD and F8260201M0014BD t'
0 2 4 6 8 Map F8260201-5, Turbine Building Interior Distance in Meters East and South Interior Walls Beta Direct Measurements
.3 5 10. 11 12 13 0
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U I0 0
N Map F8260201-6, Turbine Building (+) 20' El.
Mezzanine Grating 0 2 4 6 8 inMetem Oistance Beta Direct Measurements F8260201 M0003BD and F8260201 M0005BD
CDt 00 0
NJ CD t'-, CD Turbine Building North Interior Wall Beta Direct Measurements F8260201M0007BD to F8260201 M0011BD 0 2 4 6 8 Distance in Meters It Turbine Building West Interior Wall 00 Beta Direct Measurements F8260201 M0012BD to F8260201M0013BD Co t'Q 0 2 4 6 8 Distance in Meters Map F8260201-7, Turbine Building Exterior North and West Interior Walls Beta Direct Measurements
2 3 4 5 67 8 910 11 12 1 C
M 000 W-CIfS4 M N 0 W5 rO CD W. -fS M N 0 M5 W r- WOU0 -T'SN N0 5CCD 0f W ' W N -q '0 MO~.C N -WO0 S' WOr- V~ 0' 0M 0 N IS 0ý jO O O O0Jr.O O C C C C C O O - O O C C C W O C C CfIS S S fI i F- T - -T
_ _ __ _ __ _ __ _ _ _ _ , -L J__ _ _ _ _ _ _ 1-1 -] - L I
0 M-I L49BS U
inS ZEE 00 C) IN -lmbylm Map F8260201-8, Turbine Building (+) 20' El.
Mezzanine Grating 0 2 4 6 8 Beta Scan Measurements Distance in Meters F8260201 MO01 BS to F8260201 M01 29BS Approximate Scan Area: 129 sq. meters
C0 0
Turbine Building East Interior Wall E
E E E E Distance in meters oý from south doorwav\
'Ti COO Turbine Building South Interior Wall Map F8260201-9, Turbine Building Interior C) East and South Interior Walls ISOCS Gamma Scan Measurements F8260201M0001GS to F8260201M0005GS and 0 2 4 6 8 F8260201MOO17GS Distance in Meters 12.57 sq. meter field of view Approximate Scan Area: 75.4 sq. meters
CD 0) OD C71 0) k 3 B0 3 3 3 0 0
Turbine Building North Interior Wall 0 2 4 6 8 Distance in Meters oE E
.5 mq 2.1 n
~I1 00 0 2 4 6 8 Distance in Meters Map F8260201-10, Turbine Building Exterior North and West Interior Walls ISOCS Gamma Scan Measurements F8260201MOO06GS to F8260201MOO18GS 12.57 sq. meter field of view Approximate Scan Area: 136.5 sq. meters
Attachment 2 Instrumentation September 8, 2008 Survey Unit F8260201
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan 2
Model; Serial No. Model; Serial No. (dpm/100 cm ) (dpmll00 cm 2 )
M2350; 193700'43-68B; 190294 257 612 M2350; 1937002 43-68B; 190294 663 1,580 Tennelec; 0401171
___ ____ N/A___
___ ___ 5.88 dpm 11.71 dlpmcx,[ N/A surfaces
'For metal 2For metal grating Detector Detector Instrument Model No. Serial No. MDC Concrete - 731 dpm/100 cm2 2Cs-137, ISOCS N/A 1983920 Concrete - 591 dpm/100 cm Co-60 Concrete 2 ISOC N/ 298947 Concrete -- 903 619dpm/100 dpm/100 cm cm 2 Cs-137, Co-60 Table 2-2. Investigation Criteria and DCGL Value Param eter (dpm/100V l eC cm 2 )2 Investigation Criteria - Direct 21,500 Investigation Criteria - Scan 43,000 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 F8260201
Attachment 3 Investigation September 8, 2008 Survey Unit F8260201 (none required)
Attachment 4 Data Assessment September 8, 2008 Survey Unit F8260201
F8260201 Gross Activity Sample Results Quantile Plot I DCGL = 43000 dpm/1 00cm 2 2,500 CD) 2,000 1,500 CD) 3 1,000 634 500 CD 0
0 20 40 60 80 100 Percentile
- Direct Measurements (dpm/OOcm2) -median - - - 75th Percentile . 50th Percentile
CD 0
F8260201 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmllD00om 3000 2835 2500 0 0
E 2000-o 1500-0 0 886 E1000- 0 0 0 0 a 0 o 0 0 Q CA CL t; -500-CD am
-mm - a a ,m - a a a a a al m am am am a am a a Um am a a a am U-845
-1000
-1500 a ON O 0 0 0 0 0 0 0 0 r rO 0 4f Measurement Locations o Gross Activity - Average - - "+3SIDev a. a "-3StDev" O0 .:z: :T:::i:2* ::S.?T:;;;::S:;::
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F8260201 Gross Activity Frequency Plot DCGL = 43000 dpm/l 00cm2 8
7 6
5 0
4 3
2 0
co C~~J c'J~
00 Bins - Upper End Value (dpm/1 00cm2)