ML091000389
| ML091000389 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 09/09/2008 |
| From: | Donna Anderson Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097 | |
| Download: ML091000389 (30) | |
Text
Rancho Seco Final Status Survey Summary Report July 16, 2008 Fuel Storage Building (+) 40' El. Upper Walls & Interior Roof Survey Unit F8121004 Prepared By: _______
____Date:
______o_
FSS Engineer Reviewed By:
ate:
Lead FSS Engineer Approved By:
Date:
Dismantlement Su erintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8121004, Fuel Storage Building (+) 40' El. Upper Walls & Interior Roof Survey Unit
Description:
Operating History: The reinforced concrete structure contained the spent fuel pool and supporting systems. The building contained three main elevations including the pool.
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. Three documented instances of contamination through the common fuel building/turbine building-wall were noted.
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 on the pool elevation showed a mean gross activity level of 16,900,000 dpm/100 cm 2 and a maximum value of 200,000,000 dpm/100 cm 2. Direct measurements on the +40' elevation showed a mean gross activity level of 5,942 dpm/100 cm 2 and a maximum value of 19,357 dpm/ 100 cm 2.
Direct measurements on the building exterior showed a mean gross activity level of 1,408 dpm/100 cm2 and a maximum value of 21,600 dpm/100 cm 2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the interior of the spent fuel building was determined to be a Class 1, 2 area and the exterior was a Class 2, 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 576.9 m2 were scanned for approximately 68.7% 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 F8121004
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area:
F812 Survey Unit:
Class:
SU Area (m2):
Evaluator:
DCGL (dpm/100 cm2):
Area Factor:
Design DCGLemc (dpm/100 cm2):
LBGR (dpm/100 cm2):
Design Sigma (dpm/100 cm 2):
Type I Error:
Type II Error:
Predominant Nuclide:
Sample Area (m2):
Scan Area (m2):
Scan Coverage (%):
Zl.* :
ZI-p :
Sign P:
Calculated Relative Shift:
Relative Shift Used:
N-Value:
Design N-Value + 20%:
Design Min Samples N:
Grid Spacing L:
1004 2
839.9 D. Anderson 43,000 N/A N/A 29,107 4,631 0.05 0.05 Cs-137 60 576.9 68.7%
1.645 1.645 0.99865 3
3 11 14 14 7.0 Fuel Storage Building (+)
40' El. Upper Walls,&
Interior Roof 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 Page 3 of 8 FSS Summary Report F8121004
Survey Results:
A total of 18 direct measurements were made in F8121004. 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 < 906 dpm/100 cm 2 Co-60 and < 1,260 dpm/100 cm 2 to 991 dpm/l100 cm2 Cs-137. Beta scan activity ranged from 2,910 to 5,112 dpm/l100 cm 2, 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 Activity (dpm/100 cm)
F8121004-CO001 BD F8121004-CO002BD F8121004-Co003BD F8121004-CO004BD F8121004-CO005BD F8121004-CO006BD F81 21004-CO007BD F8121004-CO008BD F8121004-CO009BD F8121004-CO01 OBD F8121004-MOOl1BD F8121004-MOO12BD F8121004-MOO13BD F8121004-MOO14BD F8121004-MOO15BD F8121004-MOO16BD F8121004-MOO17BD F8121004-MOOl 8BD Mean:
Median:
Standard Deviation:
Ranqe:
1,727 1,561 1,644 1,509 1,541 1,592 1,681 2,697 1,961 2,033 803 769 831 741 754 877 748 923 1,355 1,525 572 741 -2.697 Page 4 of 8 FSS Summary Report F8121004
Table 3. Removable Surface Activity Results M
Measurement ID Surface Beta Activity (dpm/100 cm 2)
F8121004C0001 SM F8121004CO002SM F8121004C0003SM F8121004C0004SM F8121004C0005SM F8121004C0006SM F8121004C0007SM F8121004C0008SM F8121004CO009SM F8121004CO010SM F8121004MOOl1 SM F8121004M0012SM F8121004M0013SM F8121004M0014SM F8121004M0015SM F8121004M0016SM F8121004M0017SM F8121004M0018SM Mean:
Median:
Standard Deviation:
Range:
1.64 6.8 4.22 6.8 2.93 9.38
-0.95 10.68 4.22 15.84 0.34
-3.53 11.97
-3.53
-2.24 15.84 156.61 88.16 18.07 5.51 40.18
-3.53 to 156.61 Page 5 of 8 FSS Summary Report F8121004
Survey Unit Data Assessment:
The survey design required 18 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 F8121004
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm 2):
N/A Ambient Background Used (dpm/100 cm2):
N/A Average Ambient BKG = 0 Actual Direct Measurements (N):
18 Median (dpm/100 cm 2):
1,525 Mean (dpm/100 cm2):
1,355 Direct Measurement Standard Deviation 572 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 cm2):
572 Based on samples and backgrounds.
Maximum (dpm/100 cm2):
2,697 Material Type:
N/A Background Subtract Not Applied Sign Test Final N Value:
18 S+ Value:
18 Critical Value:
12 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 F8121004
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 F8121004 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F8121004 Maps July 16, 2008 Survey Unit F8121004
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76.25 ft. - 23.24 m 110 ft. - 33.53m N.<...
.41111 00 C) 0
.1 2
3 4
Distan ce in Meters Industrial Area Map F8121004-1, Fuel Storage Building +40' El.
East Wall (Above 10 ft) Area Estimate: 145.6 sq. meters
(b uJ 0
(ft
-e 7A 25 ft - 2324 m 76 25 ft - 23 24 rn 110 ft. - 33.53 m eli 0
1 2
3 4
Distance in Meters Map F8121004-2, Fuel Storage Building +40' El.
West Wall (Above 10 ft) Area Estimate: 146.3 sq. meters
E 0N 43 ft. - 13.72 m North Wall E
N 6t --1q.81 m Column 0
1 2
3 4
Distance in Meters 40.68 ft. - 12.4 m Interior Wall Map F8121004-3, FuelStorage Building +40' El.
North Wall (Above 10 ft) Area Estimate: 65 sq. meters Interior Wall and Column Area Estimate: 62 sq. meters Page 4 of 15 Att. I Maps F8121004
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75.375 ft - 22.97 m 14'-9" 15-0" 15-0" 15'-0" 15-7 1/2" CI U) 0 U)
U)
C-Map F8121004-4, Fuel Storage Building +40' El.
Interior Roof Area Estimate: 421 sq. meters 0.0 1.0 2.0 3.0 4.0 Distance in Meters
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F.uel Storage Building +40'El.
F Randpm Start ILocation for Beta Direct Measurements F
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I Att. 1 Maps F8121004
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4 Dislanw in Metes Map F8121004-6, Fuel Storage Building +40' El.
West Wall (Above 10 ft) Beta Direct Measurements F8121004C0001 BD to F8121004C0004BD 7.0 sq. meter grid
0) 23 3
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a)-
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Column 1
2 3
4 Dist*nce n Melers Map F8121004-7, Fuel Storage Building +40' El..
North Wall (Above 10 ft) Beta Direct Measurements F8121004C0005BD to F8121004C0007BD 7.0 sq. meter grid Page 8 of 15 Att. I Maps F8121004
100 0
E 2
0, 2
1'--
L) 0 It, 00 0
0 1
2 3
4 Distance in Meters Map F8121004-8, Fuel Storage Building +40' El.
East Wall (Above 10 ft) Beta Direct Measurements F8121004C008BD to F8121004C0010BD 7.0 sq. meter grid
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-0.31 m I11 O0 t'o E2-C:
0
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0.0 1.0 2.0 3.0 4.0 Distance in Meters E
E E
C',J Map F8121004-9, Fuel Storage Building +40' El.
Interior Roof Beta Direct Measurements F8121004CO011BD to F8121004C0018BD 7.0 sq. meter grid
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Pý Ditncei Metr Map F8121004-10, Fuel Storage Building +40' El.
West Wall (Above 10 ft.) Gamma Scan Measurements F8121004C0001GS to F8121004C0005GS 28 sq. meter field of view (4.725 m on center)
Total Scan Area: 127.1 sq. meters
Height in meters 6.0 m 2.0 m Height in meters 5.87 m Height in meters 5.4 m Height in meters 5.4 m 6
.s.
EN COe4 9
Il (Nj 3
0:-) 5' 0
5 0
1 2
3 4
Distance in Meters Map F8121004-11, Fuel Storage Building +40' El.
North Wall (Above 10 ft.) Gamma Direct Measurements F8121004C0006GS to F8121004C0009GS 12.57 sq. meter field of view F8121004C0010GS (28 sq. meter field of view)
Total Scan Area: 65.7 sq. meters Page 12 of 15 Att. I Maps F8121004
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7 0
1 2
3 4
istance in Meters Map F8121004-12, Fuel Storage Building +40' El.
East Wall (Above 10 ft.) Gamma Scan Measurements F8121004C0011GS to F8121004C0015GS 28 sq. meter field of view (4.725 m on center)
Total Scan Area: 127.1 sq. meters
(0 00 C)
C0 0P (D3t Ch_
E E
E C
(D
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(0 04 I'
Distance in meters from East Wall 2
2.4 m 6.0 m 9.4 m N
0.0 1.0 2.0 3.0 4.0 Distance in Meters Map F8121004-13, Fuel Storage Building +40' El.
Interior Roof Gamma Scan Measurements F8121004M0018GS to F8121004M0027GS 28 sq. meter field of view Total Scan Area: 238.4 sq. meters
Column Interior Wall 0
1 2
3 4
Distance in Meters Map F8121004-14, Fuel Storage Building +40' El.
North Wall (Above 10 ft.) Beta Scan Measurements F8121004MOOO1BS to F8121004C0015BS Total Scan Area: 18.6 sq. meters Page 15 of 15 Att. I Maps F8121004 Instrumentation July 16, 2008 Survey Unit F8121004
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' 433 1,033 M2350; 203481 43-68B; 1614052 257 612 M2350; 203486 43-68B; 1614002 257 612 Tennelec; 0401171 N/A 5.88 dpm a, N/A 11.71 dpmf3
'Concrete Surfaces 2Metal Surfaces.
Detector Detector Model No.
Serial No.
Concrete - 1,260 dpm/100 cm 2 Cs-137, Concrete - 906 dpm/100 cm 2 Co-60 ISOCS N/A 1983920 Metal - 719 dprril00 cm 2 Cs-137, Metal - 658 dpm/100 cm 2 Co-60 Metal - 758 dpm/100 cm 2 Cs-137, ISOCS N/A 2983947 Metal -452 dpm/100 cm2 Co-60 Table 2-2. Investigation Criteria and DCGL Parameter Value (dpm/100 cr 2)
Investigation Criteria - Direct 43,000 Investigation Criteria - Scan 43,000 Investigation Criteria - Scan (ISOCS average activity - 28 1,600 Cs-137 sq. meter field of view)
Investigation Criteria - Scan (ISOCS average activity - 12.57 4,300 Cs-137 sq. meter field of view)
DCGLw 43,000 DCGLEMC N/A Page 2 of 2 PAtt. 2 Instrumentation F8121004 Investigation July 16, 2008 Survey Unit F8121004 (none required)
Data Assessment July 16, 2008 Survey Unit F8121004
F81 21004 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/100cm2 3,000 1,500 152 AA 0
0 20 40 60 80 100 r1 Percentile Direct Measurements (dpm/100crn2) imedian
- -75th Percentile -
50th Percentile
AF8121004 Gross Activity Sample Results Scatter Plot A
DCGL = 43000 dpmI100cm=
3500 r'30010----------
3071
('4 0
E 2500 U
3 2000 0
r 0
0 4A E500 0
0 1355
-1000 o
0o 0
0 0o 0-
-1000 t
t o 0 0o 0
0 0
0 0 V-T- T-T- V l V
0 0CoSWCW 0
a 0 a0 0
0 a0 0
0aa0a 0 aaa0 Measurement Locations 70
-50 r
Grs Actvit Avrg
-7 04Se N XR0 t3 C) t beOv
(tD 0
F81 21004 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm2 CD)
CO Ci)
C:)
C.P 0r 0
4e 8
7 6
5 4
3 2
1 0
,V (I
co (NJ Bins - Upper End Value (dprn/1 00cm2)