ML082620105
| ML082620105 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/27/2008 |
| From: | Donna Anderson Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-064 | |
| Download: ML082620105 (25) | |
Text
Rancho Seco Final Status Survey Summary Report March 27, 2008 North Turbine Deck (+) 40' El.
Survey Unit F8260303 Prepared By:
- c.
id Date:
3-q 7I//2.*0o8
,FSSyni3 Reviewed By:
Date:
7 Date: 7 Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8260303, North Turbine Deck (+) 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 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/l100 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 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 cm2 and a maximum value of 3,615 dpm/100 cm2. Direct measurements on ithe 2
building exterior showed a mean gross activity level of 1,984 dpm/l00 cm 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. Direct measurement locations were determined using a random-start, fixed grid pattern and 486 m2 were scanned for approximately 60% 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 F8260303
Table 1. Survey Unit Design Parameters
/
Survey Design Value Comment Parameter Survey Area:
F826 Survey Unit:
Class:
SU Area (ml):
Evaluator:
DCGL (dpm/100 cm 2):
Area Factor:
Design DCGLemc (dpm/100 cm 2):
LBGR (dpm/.l O0 cm 2):
Design Sigma (dpm/IO0 cm 2):
Type I Error:
Type II Error:
Predominant Nuclide:
Sample Area (m2):
Scan Area (M2 ):
Scan Coverage (%):
Sign P:
Calculated Relative Shift:
Relative Shift Used:
N-Value:
Design N-Value + 20%:
Design Min Samples N:
Grid Spacing L:
0303 2
815 D. Anderson 43,000 N/A N/A 37,831 1,723 0.05 0.05 Cs-137
.58.2 486 60%
1.645 1.645 0.99865 3
3 11 14 14 7.5 North Turbine Deck (+) 40' El.
Structure Surface LTP Table 5-4 Gross Activity DCGL Class 2 Class 2 Adjusted Class 2 Class 2 Uses 3.0 if Relative Shift is
- >3 NUREG-1575 Table 5-5 Class 2 Class 2 I
Page 3 of 8 FSS Summary Report F8260303
Survey Results:
A total of 24 directmeasurements were made in F8260303. 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. All ISOCS gamma measurements were less than the Cs-137 and Co-60 MDAs.
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 Activity (dpm/100 cm)
F8260303-MOO01BD 2,270 F8260303-MOO02BD 2,016 F8260303-MOO03BD 1,849 F8260303-MOO04BD 2,024 F8260303-MOO05BD 2,389 F8260303-MOO06BD 2,198 F8260303-MOO07BD 2,151 F8260303-CO008BD 1,603 F8260303-CO009BD 1,831 F8260303-CO01OBD 1,914 F8260303-CO01 I BD 1,841 F8260303-CO01 2BD 1,717 F8260303-CO013BD 2,148 F8260303-CO014BD 2,070 F8260303-CO01 5BD 1,935 F8260303-CO016BD 2,075 F8260303-CO017BD 2,080 F8260303-CO018BD 1,935 F8260303-CO01 9BD 1,982 F8260303-CO02OBD 1,919 F8260303-M0021 BD 2,008 F8260303-MOO22BD 1,841 F8260303-MOO23BD 2,484 F8260303-MOO24BD 2,333 Mean:
2,026 Median:
2,012 Standard Deviation:
210 Range:
1,603 - 2,484 Page 4 of 8 FSS Summary Report F8260303
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)
F8260303M0001SM
-7.4 F8260303M0002SM
-4.82 F8260303M0003SM 6.8 F8260303M0004SM 0.34 F8260303M0005SM 2.93 F8260303M0006SM
-7.4 F8260303M0007SM
-2.24 F8260303C0008SM 2.93 F8260303C0009SM 1.64 F8260303C0010SM
-2.24 F8260303C0011SM 2.93 F8260303C0012SM
-2.24 F8260303C0013SM
-3.53 F8260303C0014SM
-0.95 F8260303C0015SM 1.64 F8260303C0016SM
-2.24 F8260303C0017SM
-3.53 F8260303C0018SM
-6.11 F8260303C0019SM
-3.53 F8260303C0020SM
-3.53 F8260303M0021 SM
-4.82 F8260303M0022SM 1.64 F8260303M0023SM 1.64 F8260303M0024SM
-4.82 Mean:
-1.54 Median:
-2.24 Standard Deviation:
3.69 Range:
-7.4 to 6.8 Page 5 of 8 FSS Summary Report F8260303
Survey Unit Data Assessment:
The survey design required 24 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 F8260303
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm2):
N/A Ambient Background Used (dpm/I00 cm2):
N/A Average Ambient BKG 0
Actual Direct Measurements (N):
24 Median (dpm/100 cm2):
2,012 Mean (dpm/100 cm2):
2,026 Direct Measurement Standard Deviation 210 (dpm/100 cm2):
Total Standard Deviation (dpm/100 cm2):
210 Based on samples and backgrounds.
Maximum (dpm/100 cm2) 2,484 Material Type:
N/A Background Subtract Not Applied Sign Test Final N Value:
24 S+ Value:
24 Critical Value:
16 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 7 of 8 FSS Summary Report F8260303
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 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 43,000 dpm/100 cm2 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 F8260303 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F8260303 Maps March 27, 2008 Survey Unit F8260303
00 C)Q w~
Map F8260303-1, Turbine Building Deck (+) 40' El.
Area Estimate: 2,615 sq. meters 0
2 4
6 8
D~istanc mn Meter
(D
.j F8260303: North Turbine Deck Area Estimate: 815 sq. meters Map F8260303-2, Turbine Building Deck (+) 40' El.
Area Estimate: 2,615 sq. meters (3 survey units - Class 2) 00 o
2-4.
6 8
0 -
Distance in Meters U.)
F8260304: Center Turbine Deck F8260305: South Turbine Deck Area Estimate: 953 sq. meters.
Area Estimate: 847 sq. meters
AA 00 MTD O
~Map F8260303-3, Turbine Building Deck ()40' El.
CD 0
Map F8260303-4, North Turbine Deck (+) 40' El.
Area Estimate: 815 sq. meters 0
1 2
3 4
Distance in Meters 0
0 0
0 0
00 tl 0
0 It00 C>
0 2
'4 6
8 Distance In Meters Map F8260303-5, Turbine Building Deck (+) 40' El.
Random Start Location
CtD
--I 0
F8260303: North Turbine Deck 24 Beta Direct Measurements F8260304: Center Turbine Deck 16 Beta Direct Measurements F8260305: Sou Turbine Deck 21 Beta Direct easurements bine deck, Random Start Location:
5 m from south edge of turb 2 m from west edge of grating ITJ 00 t')
0 N w-OK 0
2 4
6 8
Dishn in ML,1, Map F8260303-6, Turbine Building Deck (+) 40' El.
Class 2 Beta Direct Measurements 7.5 m by 7.5 m grid spacing
CD 00 00 0o N
Distance in Meters Map F8260303-7, North Turbine Deck (+) 40' El.
Beta Direct Measurements F8260303M0001BD to F8260303M0007BD, F8260303C0008BD to F8260303C0020BD, and F8260303M0021BD to F8260303M0024BD 7.5 m by 7.5 m grid spacing 0t 00
10 0'
r-~
00 F8260303: North Turbine Deck 42 ISOCS Gamma Scan Measurements F8260304: Center Turbine Deck 53 ISOCS Gamma Scan Measurements F8260305: South Turbine Deck 22 ISOCS Gamma Scan Measurements N
Map F8260303-8, Turbine Building Deck (+) 40' El.
ISOCS Gamma Scan Measurements 12.57 sq. meter field of view 0 24 6 8 Dist.-o h~ Mtot
C) 0 Map F8260303-9, North Turbine Deck (+) 40' El.
ISOCS Gamma Scan Measurements F8260303C0001GS to F8260303C0042GS 12.57 sq. meter field of view Approximate Scan Area: 486 sq. meters ITI 00 C)
Instrumentation March 27, 2008 Survey Unit F8260303
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No.
Model; Serial No.
(dpm/100 cm2 )
(dpmll00 cm2 )
M2350; 175834 43-68B; 190482 433 1,033 Tennelec; 0401171 N/A 5.88 dpm a, 11.71ldpmI3 N/A Table 2-2. Investigation Criteria and DCGL Value Parameter (dpml100 cm 2)
Investigation Criteria - Direct 43,000 Investigation Criteria - Scan 4,300 (ISOCS average activity)
DCGLW 43,000 DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8260303 Investigation March 27, 2008 Survey Unit F8260303 (none required)
Data Assessment March 27, 2008 Survey Unit F8260303
F8260303 Gross Activity Sample Results Quantile Plot DCGL 43000 dpm/100cm2 3,500 7,,
'~'J 3,000 -*..
...0..
S2,500o X 2,000 2012 1,500 -
500-0 20 40 60 80 100 Percentile Direct Measurements (dpm/100cm2) -
median 75th Percentile 50th Percentile
0 F8260303 Gross Activity Sample Results Scatter Plot DCG L = 43000 dpml00=cm1 3500.
3000 E
" a a a a u a a a
-a a
m a a -
a a a
a a
a a a a a 2657 2500 0
0 2000
.0.
0 2
E 0
0 0
0 0 0 0
- 1500 o
-1384 0C 1000 CD) 500 0
N 1 V I 1
1%
t I.
I 0I I
I I
wtI I
I
[ I 0 I ooeo ae e
0oe 0
.0ao~
0~~ ~~ 0ococcocooc000 00 0
Measurement Locations L7o Gross Actity -
Average -
a "+3StDev" a - _-3StDevj ko
00 Crý C~)
F8260303 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm2 C
U-C 0
7 6
5 4
3 2
1 0
N-8 N4 Bins - Upper End Value (dpn/1 00cm2)