ML081610233
| ML081610233 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 02/07/2008 |
| From: | Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-032 | |
| Download: ML081610233 (20) | |
Text
Rancho Seco Final Status Survey Summary Report February 7, 2008 Room 113 Make Up Tank Room Survey Unit F8131011 Prepared Reviewed Date.7_?2,/.
Date:_______
LeVad FSS Engineer Approved By:__
Date:
/
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8131011, Room 113 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 stru6ture. 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 cm 2 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/100 cm 2. Direct measurements on the -20' elevation showed a mean gross activity level of 247,831 dpm/1 00 cm2 and a maximum value of 10,080,000 dpm/1l00 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/1 00 cm2 and a maximum value of 1,900,000 dpm/100 cm2. Direct measurements on the +40' elevation showed a mean gross activity level of 3,288 dpm/100 cm2 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/1 00 cm2. (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 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 60 m2 were scanned for approximately 39% 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 F8131011
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area:
Survey Unit:
Class:
SU Area (m2):
Evaluator:
DCGL (dpm/1 00 cm2):
Area Factor:
Design DCGLemc (dpm/100 cm 2):
LBGR (dpm/100 cm 2):
Design Sigma (dpm/100 cm 2):
Type I Error:
Type II Error:
Predominant Nuclide:
Sample Area (m2):
Scan Area (m2):
Scan Coverage (%):
Zip,:
zj-1P :
Sign P:
Calculated Relative Shift:
Relative Shift Used:
N-Value:
Design N-Value + 20%:
Design Min Samples N:
Grid Spacing L:
F813 1011 2
155 Gary Frank 43000 N/A N/A Room 113 Structure Surface LTP Table 5-4 21500 6935 0.05 0.05 Cs-137 11 60 39%
1.645 1.645 0.99865 3.1 3
11 14 14 3.3 Gross Activity DCGL Class 2 Class 2 Default 50% DCGL 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 F8131011
Survey Results:
A total of 22 direct measurements were made in F8131011. 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 4284 to 14576 dpm/100 cm2, based on a surveyor efficiency of 0.5 and no background subtracted. InSpector scan activity for penetrations P0064 through P0068 ranged from 734 to 2760 dpm/100cm2 for Cs-137, with all scans MDA for Co-60 with a range of 812 to 2630 dpmr/100cm'. 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 F8131011-CO001BD 1592 F8131011-CO002BD 1577 F8131011-CO003BD 1587 F8131011-CO004BD 1535 F8131011-CO005BD 1468 F8131011-CO006BD 1603 F8131011-CO007BD 1660 F8131011-CO008BD 1587 F8131011-CO009BD 1598 F8131011-CO01OBD 1712 F8131011-CO011BD 1795 F8131011-CO012BD 1613 F8131011-CO013BD 1847 F8131011-CO014BD 1774 F8131011-CO015BD 1764 F8131011-CO016BD 1670 F8131011-CO017BD 1883 F8131011-CO018BD 2578 F8131011-CO019BD 2085 F8131011-CO02OBD 2158 F8131011-CO021 BD 1873 F8131011-CO022BD 1904 Mean:
1766 Median:
1691.
Standard Deviation:
253 Range:
1468-2578 Page 4 of 8 FSS Summary Report F8131011
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)
F8131011CO001SM F8131011CO002SM F8131011C0003SM F813101i IC0004SM F8131011C0005SM F8131011CO006SM F8131011 C0007SM F8131011 C0008SM F8131011 C0009SM F8131011CO010SM F8131011CO011SM F8131011C0012SM F8131011C0013SM F8131011COO14SM F8131011C0015SM F8131011C0016SM F8131011CO017SM F8131011C0018SM F8131011C0019SM F8131011 C0020SM F8131011 C0021 SM F8131011C0022SM Mean:
Median:
Standard Deviation:
Range:
2.93
-4.82
-2.24 2.93 1.64
-0.95
-3.53
-4.82
-2.24
-2.24
-0.95 13.26
-3.53 4.22 0.34 4.22 19.72 39.09 22.3 32.63 6.8 6.8 5.98 2.28 12.16
-4.82 to 39.09 Page 5 of 8 FSS Summary Report F8131011
Survey Unit Data Assessment:
The survey design required 22 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 F8131011
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):
22 Median (dpm/100 cm2):
1691 Mean (dpm/100 cm2):
1766 Direct Measurement Standard Deviation 253 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 cm 2):
253 Based on samples and backgrounds.
Maximum (dpm/1O0 cm2):
2578 Material Type:
N/A Background Subtract Not Applied Sign Test Final N Value:
22 S+ Value:
22 Critical Value:
15 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 F8131011
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, 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 43000 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 that the survey unit satisfied the release criteria and that the data quality objectives were met.
It is concluded that survey unit F813 1011 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F8131011
Attachment I Maps February 7, 2008 Survey Unit F8131011
- 5.
- 0.
1
.........I 13!....
1:
2.8m X
xx28 12 2.....
!. 88m 22m 1
D 280 n 09BD 10BD 13BD 14BD
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-M
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X.-..
3Cým 06 15 7
5m 10....
North Wall East Wall 8........ *...................
S.............
6........
2.2 7M 21BD 3.0m O
3 X
3--mm0.26m
.1.............
- .'-.0BD
.B3....... 06BD 8
0 28
-2.55m X
3 X ~
2.8
[ [
.j m 1.mm 3........................
-i 3
ot WfV............I Reflected Ceiling 21
................ I......... I I
........ + SU
'Room 113 0*
B eta D irect F8131011 M1 1
2 3
4 5
6 7
8 9
0 11 12 13 14 15 16 17 18 19 20
(DQ 00 wJ North Wall East Wall South Wall Room 113 Wall Beta Scans F8131011 - M2
(D 0
00 Floor Reflected Ceiling ROOM 113 FLOOR & REFLECTED CEILING BETA SCAN MEASUREMENTS F8131011 - M3
('D
(.A 0
00 aj North Wall East Wall 171 South Wall West Wall Room 113 Penetration Scans F8131011 - M4 Instrumentation February 7, 2008 Survey Unit F8131011
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No.
Model; Serial No.
(dpm/100 cm2 )
(dpm/100 cm2 )
M2350; 203486 43-68B; 161400 433 1033 Tennelec; 0401171 N/A 5 dpm a, 11 dpmf3 N/A Table 2.1, Survey Unit Instrumentation Detector MDC Instrument Serial No.
(dpm/1OOcm 2) 734 Cs-137 InSpector 08051294 812 00-60 812 CO-60 Table 2-2. Investigation Criteria and DCGL Value Parameter (dpmnlOO cm 2)
Investigation Criteria - Direct 43000 Investigation Criteria - Scan 43000 DCGLw 43000 DCGLEMc N/A Page 2 of 2 Att. 2 Instrumentation F8131011 Investigation February 7, 2008 Survey Unit F8131011 (none required)
Data Assessment February 7, 2008 Survey Unit F8131011
(D CD~
Ct)
Ct
(>
F81 31011 Gross Activity Sample Results Quantile Plot DCGL =43000 dpm/1OOcm 2 C14 Q=
C2 CD 0
0m 3,000 2,500 2,000 1,500 1,000 1 6 91 500 0
0 20 40 60 80 1 00 00 uj Percentile Direct Measurements (dpm/1OOcm2)
-median 75th Percentile.
50th Percentile
C'D w
o*
F8131011 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpml1 00cm 2 3000 2 2500 2524 E
2.1000 -
0 E
0 0
0 C,
0
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"+3StDev" -
"-StDev
-D CD CD 0
40 a>
a p-T 00 F8131011 Gross Activity Frequency Plot DCGL = 43000 dpm/1 OOcm 2 LL C-0 0-Oi
°I)
{0 15 14 13 12 11 10 98 7
6 5
4 3
2 10 CO oD 0o cO (0CO C)
LO i
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.Bins -Upper End Value,(dpm/lO0cm2)