ML082620149
| ML082620149 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 06/12/2008 |
| From: | Tallman D Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-064 | |
| Download: ML082620149 (34) | |
Text
Rancho Seco Final Status Survey Summary Report June 12, 2008 Aux. Bldg. Western Stairwell (-47' to -20')
Survey Unit F8130081 Prepared By: Dan A. Tallman _ Date: June 12, 2008 FSS Engineer Reviewed By 7'- J4. I ate:(4(,It)R Lead FSS Engineer Approved By: Date: 7- -o -0 Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8130081, Aux. Bldg. Western Stairwell (-47' to -20')
Survey Unit
Description:
Operating History: The Auxiliary Building is 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 -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. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, Survey Unit 813008 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 217 m2 were scanned for 100% coverage. Samples of remoyable 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 F8130081
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F813 Aux. Bldg. Western Stairwell (-47' to -20')
Survey Unit: 0081 Structure Surface Class: 1 LTP Table 5-4 SU Area (m2): 217 Evaluator: D.A.Tallman DCGL (dpm/100 cm 2): 43000 Gross Activity DCGL Area Factor: 3.6 Class 1 Design DCGLemc 154800 Class 1 (dpm#100 cm 2):
LBGR (dpm/100 cm 2): 21500 Default = 50% DCGL Design Sigma (dpml 00 cm 2): 9976 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): . 6.9 Class 1 Scan Area (m2): 217 Scan Coverage (%): 100% Class 1 1.645 Zi-P 1.645 Sign P: 0.97725 Calculated Relative Shift: 2.1 Relative Shift Used: 2.1 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: 33 Class 1 Grid Spacing L: 2.6 Class 1 Page 3 of 9 FSS Summary Report F8130081
Survey Results:
A total of 39 direct measurements were made in F8130081. 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 1825 to 1750044 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.
Page 4 of 9 FSS Summary Report F8130081
Table 2. Direct Measurement Results Measurement ID Gross Activit (dpm/100 cm F8130081-COOOIBD 1686 F8130081-C0002BD 1966 F8130081-C0003BD 2397 F8130081-CO004BD 3911 F8130081-CO005BD 6583 F8130081-CO006BD 3807 F8130081-CO007BD 2153 F8130081-CO008BD 2391 F8130081-CO009BD 1857 F8130081-CO01OBD 2537 F8130081-Co011BD .1515 F8130081-CO012BD 1302 F8130081-CO013BD 1432 F8130081-CO014BD 1452 F8130081-CO015BD 1587 F8130081-CO016BD 1235 F8130081-CO017BD 1406 F8130081-Co018BD 1421 F8130081-CO019BD 1323 F8130081-CO02OBD 1328 F8130081 -C0021 BD 1219 F8130081-CO022BD 1261 F8130081-CO023BD 1302 F8130081-CO024BD 1515 F8130081 -CO025BD 1416 F8130081 -C0026BD 1286 F8130081-CO027BD 1416 F8130081-C0028BD 1307 F8130081-C0029BD 1344 F8130081-CO03OBD 1079 F8130081-CO031BD 1214 F8130081-CO032BD 1146 F8130081-C0033BD 1333 F8130081-C0034BD 1442 F8130081-C0035BD 1333 F8130081-C0036BD 1416 F8130081-C0037BD 1369 F8130081-COO38BD 1629
.F8130081-CO039BD .1100 Mean: 1754 Median: 1416 Standard Deviation: 1014 Range: 1079-6583 Page 5 of 9 aFSS Summary Report F8130081
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpmll00 cm 2 )
F8130081CO001SM 5.51 F8130081 C0002SM 13.26 F8130081 C0003SM 1.64 F8130081 C0004SM 2.93 F81 30081 C0005SM -2.24 F8130081 C0006SM -0.95 F8130081CO007SM -0.95 F8130081 C0008SM 1.64 F8130081 C0009SM -2.24 F8130081Co010SM 1.64 F8130081CO011SM 0.34 F8130081CO012SM -2.24 F8130081Co013SM 5.51 F8130081CO014SM 0.34 F8130081CO015SM -2.24 F8130081CO016SM -2.24 F8130081CO017SM -2.24 F8130081Co018SM 0.34 F8130081Co019SM 0.34 F8130081 C0020SM 8.09 F8130081C0021SM -0.95 F8130081CO022SM -0.95 F8130081 C0023SM 9.38 F8130081 C0024SM -0.95 F8130081CO025SM 2.93 F8130081 C0026SM -2.24 F8130081 C0027SM -3.53 F8130081 C0028SM 2.93 F8130081 C0029SM -3.53 F8130081CO030SM 4.22 F8130081C0031SM 0.34 F8130081 C0032SM -2.24 F8130081 C0033SM 2.93 F8130081 C0034SM 8.09 F8130081 C0035SM -2.24 F8130081 C0036SM 2.93 F8130081CO037SM 4.22 F8130081 C0038SM -0.95 F8130081 C0039SM 0.34
.Mean: 1.21 Median: 0.34 Standard Deviation: 3.84 Range: -3.53 to 13.26 Page 6 of 9 FSS Summary Report F8130081
Survey Unit Data Assessment:
The survey design~required 39 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 F8130081
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm 2): N/A Ambient Background Used (dpm/1O0 cm 2): N/A Average Ambient BKG = 0 Actual Direct Measurements (N): 39 f Median (dpm/lOO cm 2): 1416 Mean (dpm/100 cm 2): 1754 Direct Measurement Standard Deviation 1014 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 cm 2): 1014 Based on samples and backgrounds.
Maximum (dpm/100 cm 2): 6583 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 39 S+ Value: 39 Critical Value: 25 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 F8130081
Survey Unit Investigations and Results:
Five (5) investigations (scan grids C0036, 37, 112, and junctures C0047 and 063) 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 reported demonstrating compliance with the specified acceptance criteria.
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 F8130081 meets the release criteria of 10CFR20.1402.
Page 9 of 9 FSS Summary Report F8130081
Attachment 1 Maps June 12, 2008 Survey Unit F8130081
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Attachment 2 Instrumentation June 12, 2008 Survey Unit F8130081
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No. Model; Serial No. (dpmll00 cm2 ) (dpm/100 cm2 )
930A 1680A M2350; 180733 43-98B; 148638 1400B 25208 M2350; 180733 43-94; 148620 590c 1030c M2350; 175834 43-68B; 190482 433 D 1033 D M2350; 193700 "920 43-68B; 190294 E 2195 E M2350; 149789 43-68B; 161397 M2350; 149794 43-68/5B; 149103 M2350;, 149789 43-116-1B; 256006 M2350; 149794 43-116-1B; 256005 4 9 6F 3 D M2350; 193700 43-116-1B; 216072 M2350; 175834 43-116-1B; 190642 Tennelec; 0401171 N/A 6 dpm a, 12 dpm 3 N/A A Penetration - 3" - concrete B Penetration - 4" - concrete c Penetration - 1" - concrete D Surface concrete E Surface - concrete - 1 paint'layer F Juncture - concrete Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2 )
Investigation Criteria - Direct 43000 A Investigation Criteria - Scan 43000 A DCGLw 43000 DCGLEMC 154800 A Investigation Level set conservatively at DCGLw within survey instruction package.
Page 2 of 2 Att. 2 Instrumentation F8130081
Attachment 3 Investigation June 12, 2008 Survey Unit F8130081
Table 3-1 Survey Unit Investigation
- InvesInvestigationm Investigation 'Initial Value Investigation Elevated Area Investigation DCGLemc Grid Lev (cpm) 'CMi Result Area /ml Ft DCGLemc Result Unity em (cpm) A (m acor (dpm/lOOcm2) Fraction C0036BS 2748' 3514 3514 .13 105.8 4551135 54779 0.012 C0037BS 5840 261i9 3274** NA NA NA 24018 NA C0047JS 1990 B 2785 1274** NA NA NA 27528 NA C0063JS 4260 173592c T 494 NA NA NA 4980 NA CO 112BS 5840 8168 3420** NA NA NA 25089 NA Comments:
A Adjusted for single layer paint.
B Surface Scan Investigation Level use due to survey techniques and geometry of remediated juncture c Survey instrument spike - could not be reproduced in field or in lab. Resurveyed juncture 10/15/2008
- Post remediation results Survey Unit Remainder Page 2 of 2 Att. 3 Investigation F8130081
Attachment 4 Data Assessment June 12, 2008 Survey Unit F8130081
F8130081 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpmt1 00cm2 7,000 6,000 5,000 00 1.
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2,000 1416 1,000 Cd) 0 0 20 40 60 80 100
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- Direct Measurements (dpm/l00cm2) -median - - -75th Percentile - -- - 50th Percentile I 00
F8130081 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpml100cml 7000 6000-R E 5000 479C
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F8130081 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm2 38 36 34 32 CD 30 28 26 C 24 22 20 IJ- 18 16 14 12 10 8
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