ML091000380
| ML091000380 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 09/30/2008 |
| From: | Park G Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097, F8132132 | |
| Download: ML091000380 (21) | |
Text
Rancho Seco Final Status Survey Summary Report September 30, 2008 20' Auxiliary Steam Support Survey Unit F8132132 Prepared By: Date: "
FSS Engineer Reviewed By: *4 j." Date: O-10?A Lead FSS Engineer
'z / Date: 7-Approved By:
Dismantlement Sie~rintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8132132, 20' Auxiliary Steam Support Survey Unit
Description:
Operating History: The reinforced concrete structure contained the RadWaste processing and supporting systems. The building contained six 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. One report documented contamination of the auxiliary building roof. The roof was later replaced.
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 -47' elevation showed a mean gross activity level of 320,071 dpm/100 cm2 and a maximum value of 5,720,000 dpm/100 cm 2. Direct measurements on the -29' elevation showed a mean gross activity level of 544,756 dpm/100 cm 2 and a maximum value of 11,370,000 dpm/1 00 cm 2 . Direct measurements on the -20' elevation showed a mean gross activity level of 247,831 dpm/100 cm 2 and a maximum value of 10,080,000 dpm/100 cm 2. Direct measurements on the grade elevation showed a mean gross activity level of 373,758 dpm/100 cm 2 and a maximum value of 5,800,000 dpm/100 cm 2 . Direct measurements on the +20' elevation showed a mean gross activity level of 85,408 dpm/100 cm 2 and a maximum value of 1,900,000 dpm/100 cm 2. Direct measurements on the +40' elevation showed a mean gross activity level of 3,288 dpm/100 cm 2 and a maximum value of 24,781 dpm/100 cm 2 . Direct measurements on the building exterior, including the mezzanine roof, showed a mean gross activity level of 1 897 dpm/100 cm 2 and a maximum value of 2,990 dpm/l100 cm 2. (The roof had been replaced prior to the classification survey.) Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the interior of the auxiliary 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 105 m2 were scanned for approximately 38% 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 F8132132
Table 1. Survey Unit Design Parameters
.Survey Design Value Comment Parameter Survey Area: F813 20' Auxiliary Steam Support Survey Unit: 2132 Structure Surface Class: 2 LTP Table 5-4 SU Area (m2): 276.5 Evaluator: Gary Frank DCGL (dpm/100 cm'): 43000 Gross Activity DCGL Area Factor: N/A Class 2 Design DCGLemc N/A Class 2 2
(dpm/100 cm ):
LBGR 2 (dpm/100 cm ): 21500 Default = 50% DCGL Design Sigma (dpm/100 cm ):
2 342 DTBD-06-001, Table 5-4D Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): 19.75 Class 2 Scan Area (M2 ): 105 Scan Coverage (%): 38% Class 2 ZI-* : 1.645 ZI-P* : 1.645 Sign P: 0.99865 Calculated Relative Shift: 62.8 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: 4.4 Class 2 Page 3 of 8 FSS Summary Report F8132132
Survey Results:
A total of 14 direct measurements were made in F8132132. 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. Scan activity ranged from 2188 to 26064 dpm/l 00 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/1O0 cm F8132132-COOOIBD 8678 F8132132-CO002BD 2345 F8132132-CO003BD 1847 F8132132-CO004BD 1909 F8132132-CO005BD 1784 F8132132-CO006BD 1966 F8132132-CO007BD 2023 F8132132-CO008BD .1613 F8132132-CO009BD 1790 F8132132-COOlOBD 1753 F8132132-COOI1 BD .1639 F8132132-CO012BD 1987 F8132132-CO013BD 1105 F8132132-CO014BD 1608 Mean: 2289 Median: 1818 Standard Deviation: 1860 Range: 1105-8678 Page 4 of 8 FSS Summary Report F8132132
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/1:00 cm 2 )
F8132132C0001SM 25.54 F8132132C0002SM 1 F8132132C0003SM 2.29 F8132132C0004SM 1 F8132132C0005SM -1.58 F8132132C0006SM 2.29 F8132132C0007SM -0.29 F8132132C0008SM -1.58 F8132132C0009SM -0.29 F8132132C0010SM -1.58 F8132132C0011SM 2.29 F8132132C0012SM -0.29 F8132132C0013SM -0.29 F8132132C0014SM 1 Mean: 2.11 Median: 0.35 Standard Deviation: 6.89 Range: -1.58 to 25.54 Page 5 of 8 FSS Summary Report F8132132
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 greater than the design standard deviation. Since both values of sigma resulted in a relative shift greater than three (3), no additional samples were required.
Page 6 of 8 FSS Summary Report F8132132
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): 14 Median (dpm/100 cm 2): 1818 Mean (dpm/100 Cm2 ): 2289 Direct Measurement Standard Deviation 1860 2
(dpm/100 cm ):
Total Standard Deviation (dpm/100 cm 2 ): 1860 Based on samples and backgrounds.
Maximum (dpm/100 cm 2): 8678 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: Investigate <DCGLw Pass the Sign Test? Yes Reject the Null Hypothesis? Yes Does the Survey Unit Pass All Criteria? Investigate Survey Unit Passes Page 7 of 8 FSS Summary Report F8132132
Survey Unit Investigations and Results:
No investigations were required for either direct or scan measurements and no investigation results are reported. Elevated area was discovered in the area of beta scans 71 and 74, the area was remediated and resurveyed under F8132134.
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, 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 greater than the characterization data used for survey design. However, no additional samples were required. One potential area of elevated activity was detected the area was reclassified as a Class I remediated and resurveyed under F8132134.
==
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 43000 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 F8132132 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F8132132
Attachment I Maps September 30, 2008 Survey Unit F8132132
(D Auxiliary Building Exterior 20' Auxiliary Steam Support Beta Scans North Face Delete 1 - 4 Juncture 69 ft2 Delete 82, 87 and 88 Scans 6.4 mr 2 wail drawn Incorrectly r- 1
- 4.Pr--7" - I43 I 44 1 4 4
--l I 0tý RO.1 115t~71 .1I M 72 1 73 1 74 76 05 1JS 02 24 25 40 4 69 170 71 1175 12,1 22 2 3 39 '66 67 0618'V 2(Y 03 10 0 20 24'!, , -** . ,
- 24' 04 65 02 16 17 18 34 Deflector Wall 61 62 20' Elev 01 07 l_ 14 1.Z_15 37 38 i i !__*.*
- 4j ,. . ReflectedCi ln "-
_ _ 33-11~
16 261 fir 7 489 fei 5-9 60 24.2 m2 10 IN
. _ 45.4 ml 526 ft' Looking Soulhwest 'Looking South 7. . 48.9 ml 707 ftI 189 ft" 65.7 ml 17 6 M2 -10'-.5-UDIIlectIo vail 20'-0" ELEV. Crotch Walls Screen
>'/-\ !l 2 19o}
Deleted 94 and 105 06 00 2 0 mistake in measurement It 00 U' Looking West uJ 66m' 1',.
F8132132-Ml
(D Auxiliary Building Exterior 0q 20' Auxiliary Steam Support Beta Direct 90-85 80 75 70- North Face 69 ft 6.4
-34'-S mzr 2 34..5-65-r- --- 4 2._________ - lAM 60 - 77-0m 0:722m, 1.4m 55 1I.90 09 , 25'"
> 5.'"'
50 S\ / 1134 N4 2 0.66m 2'A!e. Deflector Wall 45 Li /
20 Elev Reflected Ceiling 526 ft' 261t 24.2 m.
489 ftm 03 48.9 m2 40 Looking South 189 ft2 45.4M2 35 Deflector Wall 17.6 m2 v10.5.-1 20'-0" ELEV. Crotch Walls 30 25 20 -
Looking West 15 66mf 10--
00 ..... I . ... I . ... I .... I .... I .... I .... I .... I .... I . ... I .... I ... . I .... I .... I .... I .... I .... I .... I .... I .... I .... I .... I .... I .... I .... I .... I ..... I .... I .... I .... I .... I ....
I .... I .. I..
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 Lw 170 F8132132-M2
Auxiliary. Building Exterior 0
20' Auxiliary Steam Support Gamma Scan 90 -
85 -
80 -
GS#9 75-70-65 -
GO#10 60-GD#2 GD#9 55 -
3D#7 N 50-GD#7 cj~ 45 - GD#3 GD#6 40 -
GD#4 35-7 30 - GD#1 GS#57 /Floor 25 -
GS#4 20 -
GS#1 GS#2 GS#3 15--
10 -
5-
ýI1 00 5 10 15 20 25 30 35 40 45 50 55 60 *65 70 75 80 *85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 F81 321 32-M3
K Page 5 of 6 Att. 1 Maps F8132132
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o ::* I t Location of 20' Auxillary Steam Support inside the Industrial Area "Map F..32132-M4, Auxiliary Building 20Auxiliary Steam (A-.0 iSupport
Attachment 2 Instrumentation September 30, 2008 Survey Unit F8132132
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No. Model; Serial No. (dpm/100 cm )2 (dpm/100 cm 2 )
5.2 pCi/g 44-10; 256101 N/A Ci-g M2350; 193700 Cs-137 M2350; 175834 43-68B; 148634 433 1033 M2350; 193715 43-68B; 148630 433 1033 M2350; 193715 43-116-1B; 256007 491 739 Tennelec; 0401171 N/A 5 dpm a, 11 dpm 3 N/A Table 2-2. Investigation Criteria and DCGL Value Vmluc Parameter (dpm/100 cm2)
Investigation Criteria - Direct 43000 Investigation Criteria - Scan 43000 DCGLw 43000 DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8132132
Attachment 3 Investigation September 30, 2008 Survey Unit F8132132 (none required)
Attachment 4 Data Assessment September 30, 2008 Survey Unit F8132132
DF8132132 Gross Activity Sample Results Quantile Plot o DCGL = 43000 dpm/1 00cm2 10,000 - .*
- 9,0 0 0 -",
8,000 -*
7,000 6,000 U 5,000 4 ,0 0 0 .- * ... ....... 18 1 1,000 -
0 20 40 60 80 100 Percentile
- 0 Direct Measurements (dpm/100cm2) -median 75th Percentile - 50th Percentile
0 2o, F8132132 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmlO00cm3 1 0 00 0........ . .... ... .. ..... .. . .
0 E
6000-A f 4000
~E
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-4000 C - C - C 0
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a 0
o U 0 U 0 U 0 U 0 U 0 U 0 U 0 U 0 U 0 U 0 U 0 U U U Measurement Locations 00 o Gross Actity - Average - - "+3StDev"- - "-3StDev
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N),,
0 F81 32132 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm 2 13 12 11 10 9
8 7
.2 6 5
4 3
2 0
co It 00 Bins - Upper End Value (dpm/lOOcm2)