ML090990733
| ML090990733 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 07/23/2008 |
| From: | Alan Anderson Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097 | |
| Download: ML090990733 (29) | |
Text
Rancho Seco Final Status Survey Summary Report July 23, 2008 Fuel Storage Building (+) 40' El., Auxiliary Bldg. End, Upper Walls & Interior Roof Survey Unit F8121006 Prepared By: o. *%/jg4nd Date: ____________
FSS Engineer Reviewed By: ______ Date: I Iw oe Lead FSS Engineer Approved By: Zi/,k*I Date: 2- - O Dismantlement Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8121006, Fuel Storage Building (+) 40' El., Auxiliary Bldg. End, 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 cm 2 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 I 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 244 m 2 were scanned for approximiately 55% 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 F8121006
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F812 Fuel Storage Building (+)
40' El., Auxiliary Bldg.
End, Upper Walls &
Interior Roof Survey Unit: 1006 Structure Surface Class: 2 LTP Table 5-4 SU Area (m2): 446.1 Evaluator: D. Anderson DCGL (dpm/100 cm 2): 43,000 Gross Activity DCGL Area Factor: N/A Class 2 Design DCGLemc N/A Class 2 (dpm/100 cm 2 ):
LBGR (dpm/100 cM2 ): 29,107 Adjusted Design Sigma (dprn/100 CM2):. 4,631 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: .Cs-137 Sample Area (m2): 31.9 Class 2 Scan Area (i 2 ): 244 Scan Coverage (%): 55% Class 2 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 2 Grid Spacing L:
______________________________ J 5.6 L Class 2 Page 3 of 8 FSS Summary Report F8121006
Survey Results:
A total of 14 direct measurements were made in F8121006. 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 < 834 dpm/100 cm 2 Co-60 and < 1,240 dpm/100 ,cm 2 to 528 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)
F8121006-CO001 BD 1,743 F8121006-CO002BD 1,717 F8121006-CO003BD 2,028 F8121006-CO004BD 2,148 F8121006-CO005BD 2,080 F8121006-CO006BD 1,624 F8121006-Co007BD 1,950 F8121006-CO008BD 1,795 F8121006-MOO09BD 966 F8121006-MOOlOBD 797 F8121006-MOO 1 BD 812 F8121006-MOOl 2BD 806 F8121006-MOOl 3BD 815 F8121006-MOO14BD 880 Mean: 1,440 Median: 1,670 Standard Deviation: 554 Range: 797- 2,148 Page 4 of 8 FSS Summary Report F8121006
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/1O0 cm 2 )
F8121006CO001 SM 9.38 F8121006C0002SM -0.95 F8121006C0003SM 4.22 F8121006C0004SM 9.38 F8121006C0005SM 1.64 F8121006C0006SM 6.8 F8121006CO007SM 8.09 F8121006C0008SM 5.51 F8121006M0009SM -3.53 F8121006MOO10SM -0.95 F8121006MOOlISM 5.51 F8121006M0012SM -0.95 F8121006M0013SM -2.24 F8121006M0014SM -0.95 Mean: 2.93 Median: 2.93 Standard Deviation: 4.56 Range: -3.53 to 9.38 Page 5 of 8 FSS Summary Report F8121006
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 F8121006
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): 14 Median (dpm/100 cm 2): 1,670 2
Mean (dpm/100 cm ): 1,440 Direct Measurement Standard Deviation 554 2
(dpm/100 cm ):
Total Standard Deviation (dpm/.100 cm 2): 554 Based on samples and backgrounds.
Maximum (dpm/100 cm 2): 2,148 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 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 F8121006
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 criterionhas been met), the ALARA criterion has been met.
Changes in Initial Survey Unit Assumptions:
The stirvey unit was designed as a Class 2 structure survey and the sample results are consistent with that classification. Thevariability 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 cm 2 and none of the removable surface activity measurements exceeded 10% of the DCGL. No.investigations were required.
The directmeasurement 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 F8121006 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F8121006
Attachment 1 Maps July 23, 2008 Survey Unit F8121006
rio k) 0
~4) 33.75 ft. - 10.29 m cn It 110 ft. - 33.53m 00 C) N ,_ -w:
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Map F8121006-1, Fuel Storage Building +40' El. - Aux Bldg end 0 1 2 3 4 East Wall (Above 10 ft) Area Estimate: 64.4 sq. meters Distance in Meters
0 33.75 ft. - 10.29 m 110ft. - 33.53m t'Q =N C-..
C)
C' m -
0 1 2 3 Distance in Moters 4 Map F8121006-2, Fuel Storage Building +40' El. - Aux Bldg end West Wall (Above 10 ft) Area Estimate: 64.7 sq. meters
E 43ft. - 13.11 m South Wall T *- -ý Map F8121006-3, Fuel Storage Building +40' El. (Aux Bldg end)
DistsnCOin Meters South Wall (Above 10 ft.) Area Estimate: 76 sq. meters Page 4 of 14 Att. I Maps F8121006
CD 2'9" 2'5" 7' 6'10" 8' 8' 5'3" - 2'9" 10.5" (Fuel Storage Bldg) --- '
0 6" separation o,'
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43 ft. - 13.11 m (inside diameter) 44.75 ft. - 13.64 m (outside diameter) 00 C')
C)J CN N
I 0 1 2 3 4 Map F8121006-4, Fuel Storage Building +40' El. (Aux Bldg end)
Dis ance in Meters Interior Roof Area Estimate: 241 sq. meters
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-I- Map F811211006-5, Fuel Storale I
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Building +4,0'E. -,Aux Bldg end
-i-pp*r r-a lls-and-Interior-Roof- .-
ON ,an!dom Start Location c 0.5 1.0 1.5 2,0 flrslancA in Met1ers LInoer So)Uth Wall 4 L 0
- 4. .1 .7.iiJi 10 15 20 25 30 I I 35 ji 40 45 I
CD 0
Height in meters from floor 4.05 m -4 1 E60 D- B
! U/N
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E,'W C')
(N It 00 C)
Map F8121006-6, Fuel Storage Building +40' El.- Aux Bldg end 0 1 2 3 4 East Wall (Above 10 ft) Beta Direct Measurements Distancem Meter F8121006C0001 BD to F8121006C0002BD 5 sq. meter grid
Height in meters from floor
- 9.05 m 63 -D 4.05 m 3 3 *-- - C 0 1 2 3 4 Map F8121006-7, Fuel Storage Building +40' El. -Aux Bldg end.
Distance in Meters South Wall (Above 10 ft) Beta Direct Measurements F8121006C0003BD to F8121006CO006BD 5 sq. meter grid Page 8 of 14 Att. I Maps F8121006
CD C>
E-0 Ln 0 Cj) a) E 5 EU (al Map F8121006-8, Fuel Storage Building +40' El. -Aux Bldg end 0 1 2 3 4 West Wall (Above 10 ft) Beta Direct Measurements D~t-nc m Mot.r.
F8121006C0007BD to F8121006C0008BD 5 sq. meter grid
Distance in meters from South Wall 10.5" (Fuel Storage Bldg) -
6" separation 1
9.5 m 4.5 m
.E . FE CO
---- 00 0 6 L6 00 N CP\
Map F8121006-9, Fuel Storage Building +40' El. -Aux Bldg end Interior Roof Beta Direct Measurements 0 1 2 3 4 F8121006M0009BD to F8121006M0014BD Dis~ance in M eters 5 sq. meter grid
0Q Ch E6 C: 0 E E It
- 00 (.
c,4 Eo CN 10 00 Map F8121006-10, Fuel Storage Building +40' EL. -Aux Bldg end 0 1 2 3 4 East Wall (Above 10 ft.) Gamma Scan Measurements Distance in Mieters F8121004CO001GS to F8121004C0002GS 28 sq. meter field of view (4.725 m on center)
Total Scan Area: 52.8 sq. meters
Height in meters 5.27 m I
0 E-o C) 04 C: -
0U Map F8121006-11, Fuel Storage Building +40' El. - Aux Bldg end 0 1 2 3 4 South Wall (Above 10 ft) Gamma Scan Measurements.
Distance in Meters F8121004C0003GS to F8121004C005GS 28 sq. meter field of view, (3.92 m on center)
Total Scan Area: 70.9 sq. meters Page 12 of 14 Att. I Maps FS8121006
CD, 00 C> CD ( 0 3 3 003 3 C 00 Cr Map F8121006-12, Fuel Storage Building +40' El. - Aux Bldg end 0 1 2 3 4 West Wall (Above 10 ft) Gamma Scan Measurements Distanlce in Meters F8121004C0006GS to F8121004C0007GS 28 sq. meter field of view (4.725 m on center)
Total Scan Area: 52.8 sq. meters
0 Distance in meters from South Wall
,OGS 8.0 m
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(nWE
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00 Map F8121006-13, Fuel Storage Building +40' El. -Aux Bldg end 0 1 2 3 4 Interior Roof Gamma Scan Measurements Distance in Meters F8120006M0008GS to F8120006M001OGS 28 sq. meter field of view (3.56 m on center)
Total Scan Area: 67.5 sq. meters
Attachment 2 Instrumentation July 23, 2008 Survey Unit F8121006
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; 149789 43-68B; 161415' 433 1,033 M2350; 149789 43-68B; 161415' 257 612 T 5.88 dpm a,
., Tennelec; 0401171 N/A 11.71 dpmf3 N/A
'Concrete Surfaces 2Metal Surfaces Detector Detector Model No. Serial No.
N/A 1983920 Concrete- 1,240 dpm/100 cm 2 Cs-137, ISOCS Concrete - 834 dpm/100 cm 2 Co-60 Metal - 850 dpm/100 cm 22Cs-137, ISOCS N/A 1983920 Metal - 652 dpm/100 cm Co-60 Table 2-2. Investigation Criteria and DCGL Parameter Value (dpm/100 cm 2 )
Investigation Criteria - Direct 43,000 Investigation Criteria - Scan (ISOCS average activity- 28 1,600 Cs-137 sq. meter field of view)
DCGLw 43,000 DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8121006
Attachment 3 Investigation July 23, 2008 Survey Unit F8121006 (none required)
Attachment 4 Data Assessment July 23, 2008 Survey Unit F8121006
F8121006 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/100cm2 3,000 2,500 2,000 1: 1,500 1670 00 4-
°3 1,000 500 0
0 20 40 60 80 100 Percentile
- Direct Measurements (dpm/100cm2) -median - - - 75th Percentile - -- - 50th Percentile C')
('d 0
F8121006 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpm/l00=1e 3500 3101 N 3000 E
0 2500 o0 0 0
> 0 2000 00 4i2 1500 1 1440 a
S1000 0 0 0 0 U,
500 0
-I - - I I -221
-600 to O to M wo Mo en C to no tO O
0 r
00 IN 0
0 oU(J 0l 0
0 we 0
0 0U to 0
0 0w 0
0 0000U 0
N-0 0
0 0*
0 0
0U 00 0
0 a-0 0
4r 0
r 0
Nr 0
0 flt-0 0
8 Measurement Locations 00 Gross Activity Average "+3StDev "-3StDev 0~
IN)
C0 oN
0 F81 21006 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm 2 5
4 3
LL C
0 CDl 2 (Dl 1
0 I'). N- N-
,,N-,
N, 00 Bins - Upper End Value (dpm/100cm2)
C)
............