ML081610217
| ML081610217 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 02/05/2008 |
| From: | Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-032 | |
| Download: ML081610217 (36) | |
Text
Rancho Seco Final Status Survey Summary Report February 5, 2008 Room 112, Compactor Room Survey Unit F8130991 Prepared By:
Date:"
Reviewed By:
Date:
A Le FSS Engineer Approved By:
7 Date:
Dismantlement S perintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8130991, Room 112 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 cm2 and a maximum value of 5,720,000 dpm/l100 cm 2. Direct measurements on the -29' elevation showed a mean gross activity level of 544,756 dpmi/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 dpm/100 cm 2. Direct measurements on the grade elevation showed a mean gross activity level of 373,758 dpm/100 cm2 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/l00 cm2 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.
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 243 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 F8130991
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area:
Survey Unit:
Class:
SU Area (m2):
Evaluator:
DCGL (dpm/100 cm 2):
Area Factor:
Design DCGLemc (dpm/100 cm2):
LBGR (dpm/100 cm2):
Design Sigma (dpm/100 cm2):
Type I Error:
Type II Error:
'Predominant Nuclide:
Sample Area (m2):
Scan Area (in2):
Scan Coverage (%):
Z1-0 Sign P:
Calculated Relative Shift:
Relative Shift Used:
N-Value:
Design N-Value + 20%:
Design Min Samples N:
Grid Spacing L:
F813 0991 1
243 Gary Frank 43000 3.5
.150500 21500 6935 0.05 0.05 Cs-137 enter value 243 100%
1.645 1.645 0.99865 3.1 3
11 14 35 2.6 Room 112 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 I Class 1 Page 3 of 9 FSS Summary Report F8130991
Survey Results:
A total of 42 direct measurements were made in F8130991. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. Two measurements indicated elevated activity above the investigation level resulting in an investigation documented in Attachment 3. Scan activity ranged from 1228 to 259555 dpm/100 cm2, 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.
Table 2. Direct Measurement Results Measurement ID Gross Activity (dpmll00 cm)
F8130991-CO001BD 3823 F8130991 -CO002BD 2490 F8130991-CO003BD 2511 F8130991-CO004BD 3128 F8130991-CO005BD 2422 F8130991-CO006BD 2936 F8130991-CO007BD 2687 F8130991-CO008BD 2765 F8130991-CO009BD 2977 F8130991-COOIOBD 2791 F8130991-CO011BD 2713 F8130991-CO012BD 4331 F8130991-CO013BD
-2521 F8130991-CO014BD 2843 F8130991-CO015BD 4186 F8130991-CO016BD 2272 F8130991*C0017BD 2106 F8130991-CO018BD 2744 F8130991-CO019BD 3631 F8130991-CO02OBD 4949 F8130991-C0021BD 2282 F8130991-CO022BD 2158 F8130991-CO023BD 2713 F8130991-C0024BD 2630 F8130991-CO025BD 2225 F8130991-CO026BD 2656 F8130991-CO027BD 2635 F8130991-CO028BD 3107 F8130991-CO029BD 2827 F8130991-CO030BD 3190 F8130991-C0031BD 2931 F8130991-C0032BD 2417 F8130991-CO033BD 2563 F8130991-CO034BD 2563 F8130991-CO035BD 3175 Page 4 of 9 FSS Summary Report F8130991
Measurement ID Gross Activit (dpm/100 cm F8130991-CO036BD 3164 F8130991-CO037BD 3522 F8130991-CO038BD 8077 F8130991-CO039BD 3055 F8130991-CO04OBD 3284 F8130991 -C0041 BD 2236 F8130991-CO042BD 2101 Mean:
3008 Median:
2754 Standard Deviation:
1006 Range:
2101 -8077 Page 5 of 9 FSS Summary Report F8130991
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)
F8130991C0001SM F8130991CO002SM F8130991CO003SM F8130991C0004SM F8130991COOO5SM F8130991C0006SM F8130991CO007SM F8I30991CO008SM F8130991 C0009SM F8130991CO010SM F8130991CO011SM F8130991CO012SM F8130991CO013SM F8130991C0014SM F8130991CO015SM F8130991C0016SM F8130991C0017SM F8130991C0018SM F8130991C0019SM F8130991CO020SM F8130991C0021 SM F8130991 C0022SM F8130991 C0023SM F8130991 C0024SM F8130991 C0025SM F8130991 C0026SM F8130991 C0027SM F8130991 C0028SM F8130991 C0029SM F8130991 C0030SM F8130991C0031SM F8130991C0032SM F8130991,C0033SM F8130991 C0034SM F8130991 C0035SM F8130991 C0036SM F8130991 C0037SM F8130991CO038SM F8130991CO039SM F8130991 C0040SM F8130991 C0041 SM F8130991 C0042SM Mean:
Median:
Standard Deviation:
Range:
268.97 24.88 4.22 99.79 71.37 9.38 150.15 80.41 8.09 130.78 49.42 228.93 113.99 133.36 37.8 17.13 53.29 10.68 128.2 59.75 6.8
-0.95 214.72 151.44 0.34 139.82 53.29 8.09 46.84 138.53 41.67 2.93 23.59 11.97 27.46 21.01 10.68 59.75 21.01 33.92 5.51 5.51 64.39 39.73 68.5
-0.95 to 268.97 Page 6 of 9 FSS Summary Report F8130991
Survey Unit Data Assessment:
The survey design required 42 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 F8130991
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):
42 Median (dpm/100 cm 2):
2754 Mean (dpm/100 cm 2):
3008 Direct Measurement Standard Deviation 1006 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 cm2):
1006 Based on samples and backgrounds.
Maximum (dpm/100 cm 2):
8077 Material Type:
N/A Background Subtract Not Applied Sign Test Final N Value:
42 S+ Value:
42 Critical Value:
26 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 F8130991
Survey Unit Investigations and Results:
Two investigations (scan grids 27JS and penetration 155BS) were required for the scan measurements and the results are reported.in Attachment 3. The EMC unity rule was not exceeded as shown in Table 3-1.
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 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. Potential areas of elevated activity were
- detected and evaluated as shown in Attachment 3. 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. Two measurements indicated elevated activity above the investigation level resulting in an investigation documented in.
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 F8130991 meets the release criteria of 10CFR20.1402.
Page 9 of 9 FSS Summary Report F8130991 Maps February 5, 2008 Survey Unit F8130991
0 00 FLOOR 290 32S0 2,
- +:,*
2.6m si 2.4m 2.61 2.6m 3080 3380 x
2.6M
- 2.6 2.6m 31B0 3480 x
2.6m X
REFLECTIVE CEILING Eas Wall 2i -
2.6m 1U x
43 21Gm East Wall South Wall above opening Cj3 0.5,,
0.2.,
X 26m 3
2,6m X-2.6m 2.6m 2.6m N088 05B0 028D X
2.&m X
2.6m X
2.6.
2Gm 2.6m 0980 808D 038D X
2.Gm X
2.6m X
West Wall North Wall South Wall 00 00 0
2:
OSMUD Rooms 112 and 139 Beta Direct F8130991 - M1
,,1
- 7........10.
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1.47........ i5 -------- f6- ý.
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00 00 Cl) 00 3 S.5, 224BS 225BS 226BS 227BS 228BS 229BS 230BS 13-9jS 217B 218B 219BS220BS221B222BS223BS 2108 2118 212BS213BS214B 215BS216BS S:
03Bý 204B 205BS206BS 207B S08BS 209B8
, 196B 197B 198BS 1998 200B 41 B-202BS 1898B 190B S1918 1928 193B 194BS 195BS F ~
188 188 188 185 186 187 s188 3J FLOOR PLAN REFLECTED CEILING PLAN
(D 0
00 0
Grids on the south wall are 0.925m x 0.934m with the exception of the grids surrounding the openings which follow the boundary of the opening.
West wall is a 6 x 7 grid pattern.
l~l I 1177BSI178BS1179BSI/E,:
I MBS VMSI8OBSB 173 1748S BS
~
1 2B 163 164 "S
."165 166BS 167 1588E 1598E 16086 IBIB Room 154BE 155B8 15686S1ISM 1 50Bc 1518E 152B6 1538S SOUTH WALL 778S 78BS 798S BOBS BIBS 82BS 838S 70BS 71BS 72BS 73BS 74BS 75BS 76BS 638S 654B5 65BS 6686 67BS 68BS 6986S 56BS 57BS 58BS 59BS 60BS 61BS 62BS 49BS 50BS 51BS6 52BS 53BS 548S 5586 42BS 43BS 44BS 45BS 46BS 47BS 48BS WEST WALL SMUD Rooms 112 and 139 South and West Walls
- S9Beta Scans F8130991 -M3
0 00 41JS 42JS 161 A3 4os5.-
".IS'
-44o 46JS Ill r
WEST WALL SOUTH WALL 00*
MU Rooms 112 and 139 South and West Walls SMU Juncture Beta Scans
~F8130991
- M3A
0 00 oo 243W s
1 1
West Wall Roof o IFf stairway I
I
,4BS 115BS 116BS
-117BS
,ISS 119BS W
SOS 109,BS BS
,s BS 112BS 113BS 2BS 103BS 104BS 1056S 106BS 107BS BS 97BS 98BS
- 9OBPS, 100BS IIBS BS 91BS 92BS 93BS 94BS 958S 84BS 85BS 86BS 876S B8BS 8OBS 13OBS 131BS 239BS 24OBS 241BS 242BS A__ -S 128BS 129BS 235BS 236BS 237BS 238BS 126BS 127BS 232BS 233BS 234BS 1248S 125BS 1455S 146BS 147BS 148BS 122BS 123BS 141BS 142BS 143BS 144BS I20BS 121BS 137BS 138B5 139BS 140BS Looking North
'I; Looking East Looking South oI 00 (k)
ROOMS 112 AND 139 WALL BETA SCANS F8130991 - M4
0 00 It 00
00~
00 00 00 wj C)1
En40 00, Sý 00
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I
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53PS-ýo,.52PS 51 Ps FLOOR PLAN REFLECTED CEILING PLAN T1-1 00 C-)
Rooms 112 and 139 Floor and Ceiling Penetration Scans F8130991 - M 16 Instrumentation February 5, 2008 Survey Unit F8130991
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; 180733 43-98B; 14863811 350 630 M2350; 180733 43-98B; 148638 12 550 990 M2350; 180733 43-98B; 1-4863813 820 1490 M2350; 180733 43-98B; 14863814 930 1680 M2350; 180733 43-98B; 148638"s 1400 2520 M2350; 180733 43-98B; 14863816 1400 2520 M2350; 180733 43-94B; 1486207 950 1660 M2350; 180733 43-94B; 1486208 1550 2710 M2350; 180733 43-94B; 1486209 1610 2800 M2350; 180733 43-94B; 14862010 2630 4580 M2350; 142515 43-68B; 148453' 433 1033 M2350; 142515 43-68B; 1484535 257 612 M2350; 180738 43-68/5B; 148942' 433 1033 M2350; 142499 43-37B; 1485024 198 616 M2350; 142515 43-116-IB; 2560072 491 739 M2350; 180738 43-116-1B; 2160073 796 5895 M2350; 180738 43-116-1B; 2160732 491
- 739, Tennelec; 0401171 N/A 5 dpm a, I Idpmj3 N/A
'43-68B Concrete Surface 343-116-1B Concrete Surface 543-68B Metal Surfaces 743-94B 2" Metal Scan 943-94B 2" Concrete Scan 1143-98B 2" Metal Scan 1343-98B 4" Metal Scan 1543-98B 4" Concrete Scan 243-116-1B Concrete Junctures 443-37B Concrete Surface 643-94B 1" Metal Scan 843-94B 3" Metal Scan 1043-94B 3" Concrete Scan 1243-98B 3". Metal. Scan 1443-98B 3" Concrete Scan Page 2 of 3 Att. 2 Instrumentation F8130991
Table 2-2. Investigation Criteria and DCGL Parameter Value (dpm/100 cm 2)
Investigation Criteria - Direct 150500 Investigation Criteria - Scan 150500 DCGLW 43000 DCGLEMC 150500 Page 3 of 3 Att. 2 Instrumentation F8130991 Investigation February 5, 2008 Survey Unit F8130991
Table 3-1 Survey Unit Investigation Investigation Elevated Investigation DCGLemc Grid Investigation Initial Value Result Area (
- 2)
Factor DCGLe Result Unity Level (cpm)
(cpm)
(cpm)
(dpm/1OOcm2)
Fraction 15BS 4700 21204 960 1
15.8 679400 11949
<DCGL 27JS 14900 25746 574 1
15.8 679400 5787
-ýDCGL Survey Unit Remainder DCGL SU Mean=
N/A EMC Unity Sum N/A Investigations were performed on the following grids.
Grid P0015BS is a penetration that exceeded the DCGLemc investigation level of 4700 cpm with a count rate of 21204 cpm. The penetration was core bored to remove the activity and resurveyed with a resulting count rate of 960 cpm resulting in a final value for the survey of 11949 dpm/1 00cm2 below the DCGLw.
Grid C0027BS is a juncture that exceeded the DCGLemc investigation level of 14900 cpm with a count rate of 25746 cpm.
The juncture was remediated to remove the activity and resurveyed with a resulting count rate of 574 cpm resulting in a final value for the survey of 5787 dpm/1 00cm2 below the DCGLw.
Page 2 of 2 Ant. 3 Investigation F8130991 Data Assessment February 5, 2008 Survey Unit F8130991
00 wn Cjý A
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A CD DO Ua Co F81 30991 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmll 00cm 2 E
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Bins - Upper End Value (dpm/1 00cm2 )