ML081610169
| ML081610169 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/31/2008 |
| From: | Ellen Brown Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-032 | |
| Download: ML081610169 (24) | |
Text
Rancho Seco Final Status Survey Summary Report March 31, 2008 Ion Exchanger Valve Area Room 27 Survey Unit F8130361 Prepared By:
-Date: 3 5 /2&o3 F FS S.EZngieer Reviewed By: __7 Date:,
Lead FSS Engineer Approved By:
r 7 /
Date:
5-tC_.
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8130361, Room 27 Survey Unit
Description:
Operating History: The reinforced concrete structure contained the RadWaste processing and supporting systems. The building contained six mainelevations. 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/100 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 dpmn/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/1 00 cm2. Direct measurements on the +20' elevation showed a mean gross activity level of 85,408 dpmIO00 cm 2 and a maximum value of 1,900,000 dpm/1 00 cm 2. Direct measurements on the +40' elevation showed a mean gross activity level of 3,288 dpm/r100 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/100 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 283.9 m2 were scanned for 100% 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 9 FSS Summary Report F8130361
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area:
F813 Survey Unit:
Class:
SU Area (m2):
Evaluator:
DCGL (dpm/100 cm 2):
Area Factor:
Design DCGLemc (dpm/1O0 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 (%):
Zl-,, :
ZI-P :
Sign P:
Calculated Relative Shift:
Relative Shift Used:
N-Value:
Design N-Value + 200/o:
Design Min Samples N:
Grid Spacing L:
0361 1
283.9 Erin L. Brown 43000 3.3 142760 21500 12035 0.05 0.05 Cs-137 6.9 283.9 100%
1.645 1.645 0.955435 1.7 1.7 14 17 41 2.6 Ion Exchanger Valve Area Room 27 Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class 1 Default 50% DCGL Class 1.
Class 1 Uses 3.0 if Relative Shift is
>3 NUREG-1575 Table 5-5 Class 1 Class 1 Page 3 of 9 FSS Summary Report F8130361
Survey Results:
A total of 43 direct measurements were made in F8130361. 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 1996 to 57103 dpmr/100 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 F8130361-CO001BD 1935 F8130361-CO002BD 2111 F8130361-CO003BD 1924 F8130361-CO004BD 2262 F8130361-CO005BD 2007 F8130361-CO006BD 2127 F8130361-CO007BD 1795 F8130361-CO008BD 1873 F8130361-CO009BD 1873 F8130361-CO010BD 1675 F8130361-CO011BD 1592 F8130361-CO012BD 1899 F8130361-CO013BD 1634 F8130361-CO014BD 2018 F8130361-CO015BD 1795 F8130361-CO016BD 1748 F8130361-CO017BD 1603 F8130361-CO018BD 3548 F8130361-CO0o19BD 6790 F8130361-CO02OBD 1940 F8130361-CO021BD 1852 F8130361-CO022BD 1971 F8130361-CO023BD 1982 F8130361-CO024BD 1982 F8130361-C0025BD 1821 F8130361-CO026BD 2018 F8130361-CO027BD 1987 F8130361-CO028BD 1613 F8130361-CO029BD 1546 F8130361-CO03OBD 1650 F8130361-CO031BD 1727 F8130361-CO032BD 1753 F8130361-C0033BD 1992 F8130361-CO034BD 1899 F8130361-CO035BD 1852 F8130361-CO036BD 2096 Page 4 of 9 FSS Summary Report F8130361
F8130361-C0037BD 1966 F8130361-CO038BD
'2215 F8130361-CO039BD 1945 F8130361 -CO04OBD 1976 F8130361-CO041BD 1924 F8130361-CO042BD 2044 F8130361-CO043BD 1976 Mean:
2045 Median:
1935 Standard Deviation:
800 Range:
1546-6790 Page 5 of 9 FSS Summary Report F8130361
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm2)
F8130361 C0001 SM F8130361 C0002SM F8130361 C0003SM F8130361 C0004SM F8130361CO005SM F8130361 C0006SM F8130361 C0007SM F8130361 C0008SM F8130361 C0009SM F8130361COOIOSM F8130361C0011SM F8130361CO012SM F8130361C0013SM F8130361C0014SM F8130361CO015SM FBI30361Co016SM F8130361COO17SM F8130361COO18SM F8130361CO019SM F8130361 C0020SM F8130361C0021SM F8130361 C0022SM F8130361 C0023SM F8130361 C0024SM F8130361CO025SM F8130361 C0026SM F8130361 C0027SM F8130361 C0028SM F8130361 C0029SM F8130361CO030SM F8130361CO031SM F8130361 C0032SM F8130361 C0033SM F8130361 C0034SM F8130361 C0035SM F8130361CO036SM F8130361 C0037SM F8130361 C0038SM F8130361 C0039SM F8130361 C0040SM F8130361C0041SM F8130361CO042SM F8130361 C0043SM Mean:
Median:
Standard Deviation:
Ranqe:
-2.24
-0.95 9.38 10.68
-4.82
-0.95
-0.95
-2.24 6.8 15.84 1.64 10.68 4.22 13.26 1.64
-3.53 4.22 22.3 62.33 0.34 10.68 13.26
-3.53 10.68 0.34 8.09 1.64
-0.95
-4.82 0.34 1.64
-3.53
-3.53
-0.95 10.68
-3.53
-4.82
-4.82
-2.24
-4.82
-6.11
-2.24 2.93 3.77 0.34 11.38
-6.11 to 62.33
- .Page 6 of 9 FSS Summary Report F8130361
Survey Unit Data Assessment:
The survey design required 43 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 7 of 9 FSS Summary Report F8130361
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):
43 Median (dpm/100 cm 2):
1935 Mean,(dpm/100 cm2):
2045 Direct Measurement Standard Deviation 800 (dpm/100 cm2):
Total Standard Deviation (dpm/100 cm2):
800 Based on samples and backgrounds.
Maximum (dpm/100 cm2):
6790 Material Type:
N/A Background Subtract Not Applied Sign Test Final N Value:
43 S+ Value:
43 Critical Value:
27 Sufficient Samples Collected:
Yes Maximum Value < DCGL:
Yes Median Value < DCGL:
Yes Mean Value < DCGL:
Yes Maximum Value < DCGLemc:
Yes Class 1 Total Standard Deviation <= Sigma:
Yes Pass the Sign Test?
Yes Reject the Null Hypothesis?
Yes Does the Survey Unit Pass All Criteria?
Yes Page 8 of 9 FSS Summary Report F8130361
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 Jong 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 1 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 1 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 F8130361 meets the release criteria of 10CFR20.1402:
Page 9 of 9 FSS Summary Report F8130361
Attachment I Maps March 31, 2008 Survey Unit F8130361
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2 of 2 27 T1 C HLL Instrumentation March 31, 2008 Survey Unit F8130361
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; 180733 43-98B; 148638 N/A 1490 M2350; 180733 43-94; 148620 N/A 610 M2350; 203486 43-68B; 161400 433 1033 M2350; 193715 43-68B; 160703
.433 1033 M2350; 142509 43-68B; 160696 433
'1033 M2350; 193715 43-116-1B; 190643 N/A 3258 M2350; 203486 43-116-1B; 190173 N/A 3258 M2350; 180733 43-111B; 148641 N/A 1320 Tennelec; 0401171 N/A 5.9 dpm a, N/A 11.7 dpm P_
Table 2-2. Investigation Criteria and DCGL Value Param eter V l eC 2
(dpm/100 cm 2)
Investigation Criteria - Direct 142760 Investigation Criteria - Scan 142760 DCGLw 43000 DCGLEMC 142760 Page 2 of 2 Att. 2 Instrumentation F8130361 Investigation March 31, 2008 Survey Unit F8130361 (none required)
Data Assessment March 31, 2008 Survey Unit F8130361
F8130361 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm2 8,000 6,0 0 0 A'._.,5,.-'.
- <.o
-1 3
IV 4,
020 00 6
80100
- ~3,000
- '-;:c 2,000 T.97I 13 1,000 0
20 40 60 80 100 Percentile Direct Measurements (dpm/100cm2) median 75th Percentile 50th Percentile C:)
-o 0
0.
-TI
>0
>3 0J F8130361 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpm/100cm 2 8000 7000 E 6000 g 5000 E 4000 C-Th 3000-2000
'U 1000 0
-1000 0
0.
o*-o__0 0000 0
4445 2045
-355
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Gross Activity -
Average...
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"-3StDev..
F8130361 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm2
- " u _ 2 0 30 G) 25 2I 7;:
0 Ifl 0
1 wo*
Bins - Upper End Value (dpm/1 00cm2)
..........................