ML090980391
| ML090980391 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 12/31/2008 |
| From: | Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097 | |
| Download: ML090980391 (20) | |
Text
Rancho Seco Final Status Survey Summary Report December 31, 2008 Auxiliary Building Room 109 Survey Unit F8130942 Prepared By:
If. 2_o,)
Date: /g3//l2ooa FSS Engineer Reviewed B ate:
e25-7ate:
'o Lead FSS Engineer Approved By Date:
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8130942, Auxiliary Building Room 109 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/l100 cm' 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 dprml00 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 cm2. Direct measurements on.
the +20' elevation showed a mean gross activity level of 85,408 dpm/100 cm2 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/100 cm2 and a maximum value of 24,781 dpm/100 cm2. Direct measurements on the building exterior, including the mezzanine roof, showed a mean gross activity level of 1,897 dpm/l100 cm 2 and a maximum value of 2,990 dpm/100 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.
Page 2 of 9 FSS Summary Report F8130942
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 12 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 3 of 9 FSS Summary Report F8130942
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area:
F813 Auxiliary Building Room 109 Survey Unit:
0942 Structure Surface Class:
1 LTP Table 5-4 SU Area (m2):
12 Evaluator:
Erin L. Brown DCGL (dpm/100 cm2):
43000 Gross Activity DCGL Area Factor:
17.1 Class 1 Design DCGLemc 735730 Class I (dpm/100 cm 2):
LBGR (dpm/100 cm2):
21500 Default = 50% DCGL Design Sigma (dpm/100 cm2):
6935 Type I Error:
0.05 Type II Error:
0.05 Predominant Nuclide:
Cs-137 Sample Area (m2):
0.86 Class 1 Scan Area (m2):
12 Scan Coverage (%):
100%
Class 1 Zl_. :
1.645 ZI-0 :
1 1.645 Sign P:
0.99865 Calculated Relative Shift:
3.2 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 1 Grid Spacing L:
0.9 Class 1 Page 4 of 9 FSS Summary Report F8130942
Survey Results:
A total of 14 direct measurements were made in F8130942. 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 3727 to 68488 dpm/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 F8130942-CO001BD 1904 F8130942-CO002BD 6536 F8130942-CO003BD 29458 F8130942-CO004BD 2594 F8130942-CO005BD 2023 F8130942-CO006BD 2386 F8130942-CO007BD 9057 F8130942-CO008BD 3092 F8130942-CO009BD 2516 F8130942-CO01OBD 3263 F8130942-CO01 I BD 2889 F8130942-CO01 2BD 1738 F8130942-CO013BD 1956 F8130942-CO014BD 2215 Mean:
5116 Median:
2555 Standard Deviation:
7301 Range:
1738-29458 Page 5 of 9 FSS Summary Report F8130942
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)
F8130942C0001SM F8130942C0002SM F8130942C0003SM F8130942C0004SM F8130942C0005SM F8130942C0006SM F8130942C0007SM F8130942C0008SM F8130942C0009SM F8130942C0010SM F8130942C0011SM F8130942C0012SM F8130942C0013SM F8130942C0014SM Mean:
Median:
Standard Deviation:
Range:
2.29 2.29 1
4.87 1
2.29
-0.29 6.16 4.87 2.29 2.29
-0.29 6.16 7.46 3.03 2.29 2.47
-0.29 to 7.46
.Page 6 of 9 FSS Summary Report F8130942
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. However, both values of sigma resulted in a relative shift greater than three so no additional samples were required.
Page 7 of 9 FSS Summary Report F8130942
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):
2555 Mean (dpm/100 cm2):
5116 Direct Measurement Standard Deviation.
7301 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 cm2):
7301 Based on samples and backgrounds.
Maximum (dpm/100 cm 2):
29458 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:
Yes Class 1 Total Standard Deviation <= Sigma:
Investigate No additional Samples required 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 F8130942
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 1 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. No potential areas of elevated activity were detected. Therefore the EMC criterion was met.
==
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 F8130942 meets the release criteria of 10CFR20.1402.
Page 9 of 9 FSS Summary Report F8130942
Attachment I Maps December 31, 2008 Survey Unit F8130942
I I
1 III 1101 1091 IScale Feet
- JESTFMA!TEO FLOORSURF:ACEP.REA'
,Scale Meters STotal Area-2562 m 0
1 2
3 o~o AUXILIARY BUILDING EL. 0!-O "
________ROOM_"iiFLOOR-ROOM 109 ANDROOM 110 BETA SCAN LOCATION 109 rSACRMENTO MUNICPAL F8130942-Mi u-LfV DISTRICTo IQLE FLOOR.0 HEO T 109N ROOM 110 Gne FILE: 81300003 SHEET 1 of 1 J Grinley
0 CI2 00 w-Key Plan.
Floor
- SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT AUXILIARY BUILDING EL. 0'-0" FLOOR - ROOM 109 AND ROOM 110 BETA DIRECT/LOOSE MEASURMENT LOCATIONS F8130942-M2 FILE: 813000.03 SHEET 1 of 2 J Grinley
II I
iiI i
Key Plan 4--
Corridor I
Enr ROOM 1091 Scale Feet 7
3122= I'-0,.
ESTIMATED FLOOR SURFKCE AREA Scale MeterS Total Area - 256.2 m 0
1 2
3 IoI*I"AUXILIARY BUILDING EL. 0'-0" iFLOOR
- ROOM 109 AND ROOM 110 LI SMUK BETA DIRECT/LOOSE MEASURMENT LOCATIONS Floor SACRAMENTo MUNICIPAL F8130942-M2 Flor UTILITY DISTRICT Fi F: Rt1303l,
SHEET 2 of 2' J GOdnley Instrumentation December 31, 2008 Survey Unit F8130942
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No.
Model; Serial No.
(dpmll00 cm 2)
(dpm/100 cm2 )
M2350; 193715 43-68B; 148630 433 1033 M2350; 193715 43-116-1B; 256007 N/A 3258 M2350; 180733 43-111B; 148641 N/A 1320 Tennelec; 0401171 N/A 4.9 dpm oa, N/A 8.2 dpm.3 The MDC's listed are the most conservative for the actual survey performed.
Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2)
Investigation Criteria - Direct 735730 Investigation Criteria - Scan 735730 DCGLW 43000 DCGLEMC 735730 Page 2 of 2 Att. 2 Instrumentation F8130942 Investigation December 31, 2008 Survey Unit F8130942 (none required)
Data Assessment December 31, 2008 Survey Unit F8130942
F8130942 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm2 35,000 -
30,000
Ž 25r,000
~20,000.
>"15,000 CD) 5,000 A-77777 7FJZ 2555 0
20 40 60 80 100 Percentile Direct Measurements (dpm/100cm2) --
median -
- - 75th Percentile....
50th Percentile
CD 4jA F8130942 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmtl00ema A
S(0' p*
U) a*
40000 N
30000 E
U o 20000 Ea-10000
- 0 p0 cC10000 -
-20000 0
S-
-m a -
m a
m-a a
a C
0 0
o 0
o 0
C I
I I
I n
en en en en en en en en en e
en en en r
tN0 t0) 0 C
0 0-r-
('4 fl f-o a
0 0
0 a
0 0
a 0
0 o
0 0
0 0
0 0
0 0
0 0
0 0
0 U
U U
U U
U U
U U
U U
U U
U Measurement Locations o
Gros.sAcivity.
Average
"+3StDev"
"-3StDe 127018 5116
-167BE
ctz U)
F8130942 Gross Activity Frequency Plot DCGL = 43000 dprT/1 00cm2 11 10 U-0D I
9 8-7 6
5 4
3 2
0 00 00 R
00 cc 171 00 Bins - Upper End Value (dpm/1 00cm2)
........