ML082620163
| ML082620163 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 07/30/2008 |
| From: | Tallman D Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-064 F8130461 | |
| Download: ML082620163 (24) | |
Text
Rancho Seco Final Status Survey Summary Report July 11, 2008 Pump Alley - South and West concrete walls below 25'9" Survey Unit F8130461 Prepared By: Dan A. Tallman ate: July 11, 2008 FSS Engineer Reviewed By:_ Date: -71 24 O0 Lead FSS Engineer Approved By: Date: 7 3 -
Dismantlement Seperintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8130461, Pump Alley - South and West concrete walls below 25'9" Survey Unit
Description:
Operating History: The Auxiliary Building was a reinforced concrete structure that 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.
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 -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. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the southern and western walls of Pump Alley below -25'9" within the interior of the auxiliary building was determined to be a Class 1 area.
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 160 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 F8130461
Table 1. Survey Unit Design Parameters Survey Design Parameter Value I Comment Survey Area: F813 Pump Alley - South and West concrete walls below 2519" Survey Unit: 0461 Structure Surface Class: 1. LTP Table 5-4 SU Area (m2): 159.6 Evaluator: D.A.Tallman DCGL (dpm/100 cm ):
2 43000 Gross Activity DCGL Area Factor: 3.5 Class 1 Design DCGLemc 1.53313 Class I (dpm/1 00. cm 2):
LBGR (dpm/100 cm 2): 21500 Default 50% DCGL Design Sigma (dpm/100 cm 2): 10204 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): 6.93 Class 1 Scan Area (M2): 159.6 Scan Coverage (%): 100% Class 1 ZI-, : 1.645 ZI-P : 1.645 Sign P: 0.97725 Calculated Relative Shift: 2.1 Relative Shift Used: 2.0 Uses 3.0 if Relative Shift is
>3 N-Value: 12 Design N-Value + 20%: 15 NUREG-1575 Table 5-5 Design Min Samples N: 23 Class 1 Grid Spacing L: 2.6 Class 1 Page 3 of 9 FSS Summary Report F8130461
Survey Results:
A total of 36 direct measurements were made in F8130461. The results including mean, median,' standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. Multiple scan measurements indicated areas of elevated activity. Scan activity ranged from 3829 to 5550920 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 Attachment 2.
Page 4 of 9 FSS Summary Report F8130461
Table 2. Direct Measurement Results Measurement ID Gross Activit (dpm/100 cm F8130461-COOOIBD 1800 F8130461-C0002BD 2127 F8130461-CO003BD 1520 F8130461-CO004BD 4124 F8130461-COOO5BD 2002 F8130461-CO006BD 2376 F8130461-CO007BD 1655 F8130461 -CO008BD 2122 F8130461-CO009BD 1904 F8130461-COOIOBD 1914 F8130461-CO011BD 1878 F8130461-CO012BD 3486 F8130461-CO013BD 1987 F8130461-CO014BD 5006 F8130461-CO015BD 2231 F8130461-CO016BD 2256 F8130461-CO017BD 1940 F8130461-CO018BD 2983 F8130461-CO019BD 1701 F8130461-CO02OBD 3450 F8130461 -C0021 BD 1899 F8130461-COO22BD 4990 F8130461-CO023BD 1914 F8130461-CO024BD 7081 F8130461 -CO025BD 1883 F8130461-CO026BD 2231 F8130461-CO027BD 1748 F8130461-CO028BD 1940 F8130461-CO029BD 2205 F8130461-CO03OBD 1686 F8130461-C0031BD 1857 F8130461 -CO032BD 2251 F8130461-CO033BD 1914 F8130461-CO034BD 1919 F8130461-CO035BD 1878 F8130461-CO036BD 1727 Mean: 2433 Median: 1940 Standard Deviation: 1172 Range: 1520-7081 Page 5 of 9 FSS Summary Report F8130461
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2 )
F8130461CO018SM -3.53 F8130461 C0029SM -3.53 F8130461COOOISM -2.24 F8130461 C0002SM 2.93 F8130461 C0003SM -3.53 F8130461 C0004SM 0.34 F8130461 COOO5SM -2.24 F8130461 C0006SM 0.34 F8130461CO007SM -2.24 F8130461CO008SM -4.82 F8130461 C0009SM 0.34 F8130461CO010SM -0.95 F8130461CO011SM 1.64 F8130461CO012SM 0.34 F8130461CO013SM -0.95 F8130461CO014SM -0.95 F8130461CO015SM -3.53 F8130461C0016SM -3.53 F8130461CO017SM -0.95 F8130461CO018SM 0.34 F8130461CO019SM -0.95 F8130461CO020SM 5.51 F8130461C0021SM -3.53 F8130461 C0022SM -3.53 F8130461 C0023SM -2.24 F8130461 C0024SM 9.38 F8130461 C0025SM 0.34 F8130461,CO026SM 0.34 F8130461 C0027SM -3.53 F8130461CO028SM -4.82 F8130461 C0029SM -3.53 F8130461CO030SM -0.95 F8130461 C0031SM -2.24
-2.24 F8130461 C0033SM -3.53 F8130461 C0034SM -3.53 F8130461 C0035SM -4.82 F8130461CO036SM -0.95 Mean: * -1.35 Median: -2.24 Standard Deviation: 2.87 Range: -4.82 to 9.38 Page 6 of 9 FSS Summary Report. F8130461
Survey Unit Data Assessment:
The survey design required 36 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 F8130461
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpnV100 cm 2): N/A Ambient Background Used (dpm/100 cm 2): N/A Average Ambient BKG = 0 Actual Direct Measurements (N): 36 Median (dpm/100 cm 2): 1940 Mean (dpm/100 cm ):2 2433 Direct Measurement Standard Deviation 1172 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 cm 2): 1172 Based on samples and backgrounds.
Maximum (dpm/100 cm 2): 7081 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 36 S+ Value: 36 Critical Value: 23 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 F8130461
Survey Unit Investigations and Results:
Twenty-seven (27) investigations 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 (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. 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. The investigations required were performed and documented.
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 F8130461 meets the release criteria of 10CFR20.1402.
Page 9 of 9 FSS Summary Report F8130461
Attachment 1 Maps July 11, 2008 Survey Unit F8130461
(5 k) Doting Shel 0
F boting Bottor I Surface Area Estknates:
Wall Concmrele 159.6 M2 TOTALAREA = 159.6 ml
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Attachment 2 Instrumentation July 11, 2008 Survey Unit F8130461
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No. Model; Serial No. (dpmll00 cm 2 ) (dpmll00 cm 2 )
M2350; 193715 44-10; 171374 NA 16756' M2350; 193700 43-68B; 160691 433 1033 M2350; 149789 43-68B; 148633 433 1033 M2350; 193715 43-68B; 148630 433 1033 M2350; 193715 43-116-IB; 190643 796 3258 Tennelec; 0401171 N/A 6 dpm a, 12 dpm J3 N/A I Bkgd < 8000 cpm Table 2-2. Investigation Criteria and DCGL Parameter Value cm 2 )
dmlue (dpm/100 c2 Investigation Criteria - Direct 43000 Investigation Criteria - Scan 43000' DCGLw 43000 DCGLEMC 153313 1Investigation level for gamma scan (44-10) of moisture barrier and concrete soil interface set at three times average background (bkgd = 4341 cpm) observed within pump alley Page 2 of 2 Att. 2 Instrumentation F8130461
Attachment 3 Investigation July 11, 2008 Survey Unit F8130461
Table 3-1 Survey Unit Investigation T ITinvestigation Result DCGLernc Unity Investigation Initial Value Investigation Elevated Area DCGLemc Grid Level (cpm) (cpm) Result (cpm) Area (m 2) Factor i Result Frati Fraction
-- F 1141(dpm/llOOcm2)
BS07 5840 11741 1 0.03 433.6 18644800 I 86132 0.004 BS09 5840 15329 15329 [ 0.06 218.3 9384750 112453 0.012 BS11 5840 T 14626 14626 [ 0.03 218.3 9384750 107296 0.011 BS48 5840 10261 10261 0.04 433.6 18644800 75274 0.004 BS64 5840 6185 6185 0.05 326.1 14022300 45373 0.003 BS68 5840 8364 8364 0.05 261.4 11241920 61358 0.005 BS70 5840 6248 6248 0.05 261.4 11241920 45835 0.004 BS72 5840 6827 6827 0.04 261.4 11241920 50083 0.004 BS74 5840 9158 9158 NA 326.1 14022300 67183 0.005 BS75 5840 24716 2601"* 1 NA NA { NA < DCGLw NA BS77 5840 1 11899 496* [ NA [ A NA < DCGLw NA BS79 5840 17535 2968** NA NA NA < DCGLw NA BS151 5840 9421 2766** NA NA NA < DCGLw NA BS155 5840 11839 11839 0.03 433.6 18644800 86850 0.005 BS157 5840 6854 6854 0.01 1294.1 55646300 50281 0.001 J14BS 1990 2605 2605 0.31 44 1891140 59256 0.030 J03GS 12000 138773 10155** 0.05 256.4 11023910 397738 0.036 J07BS 12000 12209 13219** 0.05 256.4 11023910 517744 0.047 J11GS 12000 13521 10741** 0.05 256.4 11023910 420689 0.038 J13GS 12000 16114 8199** 0.05 256.4 11023910 321128 0.029 J10GS* 12000 11260 6786** 0.05 256.4 11023910 265785 0.024 J16GS 12000 19329 11913** 0.05 256.4 11023910 466593 0.042 J33GS 12000 14952 8412** 0.05 256.4 11023910 329470 0.030 J34GS 12000 12386 7079** 0.05 256.4 11023910 277261 0.025 J37GS 12000 12472 9211** 0.05 256.4 11023910 360764 0.033 J38GS 12000 15381 .14814** 0.05 256.4 11023910 580215 0.052 J40GS 12000 13302 7982** 0.05 256.4 11023910 312628 0.028 J45GS 12000 24309 6568** 0.05 256.4 11023910 257247 0.023 Comments:
- Gamma evaluation of J14BS
- Post remediation results Survey Unit Remainder DCGL = SU Mean = 0.057 43,000 2433 EMC Unity Sum 0.552 Page 2 of 2 Att. 3 Investigation F8130461
Attachment 4 Data Assessment July 11, 2008 Survey Unit F8130461
F81.30461 Gross Activity Sample Results Quantile Plot 2
DCGL = 43000 dpmllOOcm 8,000 7,000 6,000 5,000 ZI 4,000 3,000 (D2 2,000 1940 1,000 0
0 20 40 60 80 100 Percentile 00 w~
Direct Measurements (dpm/1OOcm2) -median - 75th Percentile .. 50th Percentile
0 K 0
F8130461 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmll00cm=
8000 7000
~~~~~~~-
E 6000 a- - - - - - -- ---- - a a a- - a 5BSC U
C 5000 0 0 4000 0 0 0
-41 3000 0 2431
<C 2000 0 0 0 00 00 00 0 0 0 0 0 0 1000 CD) 0.
-1000. -1085
-2000 ooooccoocooco0oooooD0ccooo0accoccD0c Cd) 0 0000c00 OCCCvrrrwrrrtJN T N0000 uuuuuuuuuuuuuuuuuuuuuuvuuuUUuUUuuuU Measurement Locations o Gross Activity -
Average. . a a
"+3StDev
- a "3StDev" . ..... . .... ....... ... ...
ON
0 F8130461 Gross Activity Frequency Plot DCGL = 43000 dpm!1 00cm2 30 28 26 24 22 20 U- 18 C 16 00 0 14 12 10 8
6 4
4d, 2 0
O 8
Bins - Upper End Value (dpm/1 00cm2).