ML082620157
| ML082620157 | |
| 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 F8130161 | |
| Download: ML082620157 (28) | |
Text
Rancho Seco Final Status Survey Summary Report June 17, 2008 AB -20' corridor column R-T Survey Unit F8130161 Prepared By: Dan A. Tallman A Date: June 17, 2008 FSS Engineer Reviewed By:'.ý_*9 - Date:. 8 Lead FSS Engineer Approved By: Date:__ __
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8130161, AB -20' corridor column R-T 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. The 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/1 00 cm 2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the main east - west corridor between columns R and T in the -20' elevation of 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 310.1 m 2 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 F8130161
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F813 AB -20' corridor column R-T Survey Unit: 0161 Structure Surface Class: 1 LTP Table 5-4 SU Area (m2): 310.1 Evaluator: D.A.Tallman DCGL (dpm/100 cm'): 43000 Gross Activity DCGL Area Factor: 3.58 Class I Design DCGLemc 153867 Class I (dpm/100 cm 2):
LBGR (dpm/100 cm'): 21500 Default = 50% DCGL Design Sigma (dpm/100 cm )"2 12035 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): 6.89 Class 1 Scan Area 2 (M ): 310.1 Scan Coverage (%): 100% Class 1 1.645 1.645 Sign P: 0.955435 Calculated Relative Shift: 1.7 Relative Shift Used: 1.7 Uses 3.0 if Relative Shift is
.>3 N-Value: 14 Design N-Value + 20%: 17 NUREG-1575 Table 5-5 Design.Min Samples N: 45 Class 1 Grid Spacing L: 2.6 Class 1 Page 3 of 9 FSS Summary Report F8130161
Survey Results:
A total of 47 direct measurements were made in F8130161. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. No FSS measurements indicated areas of elevated activity.
Scan activity ranged from 1482 to 54498 dpm/100 cm2 , based on a surveyor efficiency of 0.5 and no background subtracted. ISOCS scan activity on the walls and ceiling ranged from 1116 to 12,300 dpm/100cm 2 for Cs-137 with all scans MDA for Co-60. 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 F8130161
Table 2. Direct Measurement Results Measurement ID Gross Activit (dpm/100 cm)
+
F8130161-C0001BD 1717 F8130161-CO002BD 1712 F8130161-CO003BD 1696 F8130161 -Co004BD 1826 F8130161 -CO005BD .1790 F8130161-CO006BD 1504 F8130161 -CO007BD 1624 F8130161 -CO008BD 1592 F8130161 -Co009BD 1535 F8130161-CO0IOBD 3035 F8130161 -Coo I BD 3916 F8130161--Co012BD 2443 F8130161-C0013BD 2511 F8130161--Co014BD 2832 F8130161--Co015BD 5239 F8130161-CO016BD 1899 F8130161-CO017BD 1914 F8130161-COOlBBD 2163 F8130161-CO019BD 2116 F8130161-CO02OBD 1515 F8130161 -C0021 BD 1369 F8130161 -CO022BD 1639 F8130161 -CO023BD 1411 F81 30161 -CO024BD 1608 F8130161-CO025BD 1629 F8130161-CO026BD 1530 F8130161-CO027BD 1286 F8130161 -CO028BD 1442 F8130161 -CO029BD 1572 F8130161-CO03OBD 1390 F8130161-CO031BD 1660 F8130161 -CO032BD 1499 F8130161-CO033BD 1421 F8130161 -CO034BD 1489 FB130161 -CO035BD 1375 F8130161 -CO036BD 1390 F8130161-CO037BD 1733 F8130161-CO038BD 1644 F8130161 -CO039BD 1520 F8130161 -CO04OBD 1541 F8130161-CO041BD 1582 F8130161 -CO042BD 1432 F8130161 -CO043BD 1598 F8130161-CO044BD 1561 F8130161 -CO045BD 1468 F8130161-CO046BD 1577 F8130161-CO047BD 1551 Mean: 1819 Median: 1592 Standard Deviation: 705 Ranqce: 1286-5239 Page 5 of 9 FSS Summary Report, F8130161
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpmll00 cm 2)"
F8130161 COON SM -0.95 F8130161 C0002SM -3.53 F8130161 C0003SM -2.24 F8130161 C0004SM -0.95 F8130161COOO5SM 0.34 F8130161 C0006SM -2.24 F8130161 C0007SM -2.24 F8130161 C0008SM -0.95 F8130161 C0009SM -3.53 F8130161CO010SM 0.34 F8130161CO011SM 2.93 F8130161CO012SM 2.93 F8130161CO013SM 2.93 F8130161CO014SM 1.64 F8130161CO015SM -0.95 F8130161 Co016SM 5.51 F8130161 CO017SM 17.13 F8130161 COW08SM 1.64 F8130161C0019SM -2.24 F8130161 C0020SM 17.13 F8130161CO02ISM -4.82 F8130161 C0022SM 5.51 F8130161CO023SM -3.53 F8130161 C0024SM 15.84 F8130161 C0025SM 2.93 F8130161 C0026SM -2.24 F8130161 C0027SM -3.53 F8130161 C0028SM -3.53 F8130161 C0029SM -3.53 F8130161 C0030SM -2.24 F8130161CO031SM 4.22 F8130161C0032SM 0.34 F8I 30161 CO033SM 1.64 F8130161CO034SM 8.09 F8130161 C0035SM -0.95 F8130161 C0036SM -2.24 F8130161 C0037SM 19.72 F8130161 C0038SM 4.22 F8130161CO039SM 11.97 F8130161 C0040SM 0.34 F8130161CO041SM 24.88 F8130161 CO042SM 1.64 F8130161C0043SM .13.26 F8130161 C0044SM 0.34 F8130161C0045SM 15.84 F8130161 C0046SM 1.64 F8130161 C0047SM 13.26 Mean: 3.23 Median: 0.34 Standard Deviation: 7.3 Ranqe: -4.82 to 24.88 Page 6 of 9 FSS Summary Report F8130161
Survey Unit Data Assessment:
The survey design required 47 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 F8130161
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm 2): N/A Ambient Background Used (dpmlO00 cm'): N/A Average Ambient BKG = 0 Actual Direct Measurements (N): 47:
Median (dpm/100 cm 2): 1592 Mean (dpm/1OO cm2): 1819 Direct Measurement Standard Deviation 705 (dpmr/100 cm 2)"
2 Total Standard Deviation (dpm/100 cm ): 705 Based on samples and background§.
Maximum (dpm/100 cm 2): 5239 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 47 S+ Value: 47 Critical Value: 29 Sufficient Samples Collected: Yes Maximum Value < DCGL: Yes Median Value < DCGL: Yes Mean Value < DCGL: Yes Maximum Value < DCGLemc: Yes Class I 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 F8130161
Survey Unit Investigations and Results:
No investigations were required based on the results of the FSS performed within this survey unit.
During routine surveillance surveys utilizing the 44-10 Nal detector, discovery was made in grids 24/25, 26/27, 32/33, & 34/35. The results of this discovery are detailed in attachment 3. The EMC unity rule was not exceeded as shown in to 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 required investigations were performed.
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 F8130161 meets the release criteria of 10CFR20.1402.
Page 9 of 9 FSS Summary Report F8130161
Attachment 1 Maps June 17, 2008 Survey Unit F8130161
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Attachment 2 Instrumentation June 17, 2008 Survey Unit F8130161
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No. Model; Serial No. (dpmll00 cm 2 ) (dpm/100 cm 2 )
M2350; 180733 43-98B; 148638 350A 630 A M2350; 175834 43-68B; 190482 M2350; 203486 43-68B; 190476 M2350; 193700 43-68B; 190294 433 B 1033 B M2350; 149789 43-68B; 161397 M2350; 142509 43-68B; 160699 M2350; 180738 43-68/5B; 148942 M2350; 180738 43-116-1B; 216073 796 B 3258 B M2350; 175834 43-116-1B; 190642 796c 3258c M2350; 203486 43-116-1B; 190173 491D 739D M2350; 203482 44-10; 211672 NA 16756 Tennelec; 0401171 N/A 6 dpm (x, 12 dpmj3 N/A A Penetration - 2" - metal B Structure - surface - concrete c Penetration - 4" to 14" - Concrete D Juncture - concrete Instrument Detector MDC Model; Serial No. Model; Serial No. (dpm/100 cm2 )
ISOCS 1983920 1030 (Co6s)
________________________________1420 (Csl137)
' 3920_2m concrete geometry 12.5 m2 FOV Table 2-2. Investigation Criteria and DCGL Value Parameter (dpml100 cm 2)
Investigation Criteria - Direct 153867 Investigation Criteria - Scan' 153867 DCGLw 43000 DCGLEMC 153867 Scan Investigation Level for routine 44-10 surveillance scan set at 20,000 cpm (- 60%
DCGLEMC 0.75 mi2 )
Value (dPml1oo cm?)
Instrument Parameter To detect a I m hot spot at the EMC Criterion within the detector field of view Investigation Criteria - 63,300 dpmr100 cm22Cs-137 ISOCS Concrete Scan 1 21,275 dpm/100 cm Co-60 3920_2mconcrete geometry 12.5 M 2 FOV Page 2 of 2 Att. 2 Instrumentation F8130161
Attachment 3 Investigation June 17, 2008 Survey Unit F8130161
Table 3-1 Survey Unit Investigation Investigation Investigation DCGLemc Gfd' Investigation Initial Value Result Elevated Area DCGLemc Result Unity Level (cpm) (cpm) (cpm) Area (m 2) Factor (dpm/lOOcm2) Fraction C24/25GS 20000 32000 4000 0.33** 41.48 1,783,640 ] 155,255 0.086 C26/27GS 20000 82000 12000 0.01 1294.1 55,646,300 465,766 0.008 C26/27GS C32/33GS 20000 20000 35000 52000 f[ 8000 4000 0.78**
0.50**
J. 18.70 28.10 804,100 1,208,300 310,511 0.384 155,255 0.127 C32/33GS 20000 49000 4000 0.50** 28.10 1,208,300 155,255 1 0.127 C34/35GS 20000 29000 4000 0.26** 51.86 2,229,980 155,255 1 0.069 C24/25GS N/A N/A 1379 0.33" 41.48 1,783,640 j 10,116 0.047 2 C26/27GS N/A N/A 2488 0.78** 18.70 804,100 1 18,252 0.020 2 C32/33GS N/A N/A [ 1470 0.50** 28.10 1,208,300 10,784 0.014 2 C32/33GS N/A N/A 1507 0.50** 28.10 1,208,300 11,055 0.004 2 C34/35GS N/A N/A 1511 0.26"* 51.86 2,229,980 11,085 0.015_
Juncture G25 N/A N/A 2014 0.1" 1 131.6 5,658,800 45,812 3 0.008 2 Juncture G26 N/A N/A 1624 0.1* 131.6 5,658,800 36,941 ' 0.006 2 Juncture G33 N/A N/A 2175 0.1* 131.6 5,658,800 49,475 3 0.008 2 Juncture G34 N/A N/A 976 0.1* 131.6 5,658,800 22,201 3 0.004 2 Juncture G41 N/A N/A 552 0.1* 131.6 5,658,800 12,556 3 0.002 2 Comments:
- Elevated juncture area estimated at 2" by one meter.
- Elevated area conservatively estimated at the-surface area of the remediation foot print 1 Discovery made during routine surveillance with 44-10. Insufficient survey documentation available to distinguish exact FSS grid identification.
FSS grids corresponding to surveillance location are as indicated (including the adjacent juncture).
2 Post remediation verification survey included beta scan survey measurements of grid and accompanying juncture area. (EMC Unity 3Juncture remediation resulted in a geometry most accurately conforming to thatof the Cs1 37 surface scan selected in the DQA. Sum = 0.170)
Survey Unit Remainder DCGL = SU Mean =
43,000 1821 0.042 EMC Unity Sum 0.809 Page 2 of 2 Att. 3 Investigation F8130161
Attachment 4 Data Assessment June 17, 2008 Survey Unit F8130161
F81 30161 Gross Activity Sample Results Quantile Plot 0 DCGL = 43000 dpm/1 00cm2 6,000 5,000 4,000 I 3,000 Ci2 3
2,000 1692 1,000 0
0 20 40 60 80 100 Percentile 00
- Direct Measurements (dpml100cm2) rmedlan - - -75th Percentile -.-- 50th Percentile
0 F8130161 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmil00cm1 6000 4 0
5000 E 00 4000 393E 3000 O 0".
a
- 0. 00 2000 00 CD 0 000 O0 0000 0 00000 0000000000 CD 1000 m *
- mm *
- m m m m *000000000*
- m
- 0
-297 C -1000 OMOOOOODoDOOOOooooooooooooaoooooocoooo0ooooooo Ctow a""Vi u MAW0ment onE P Measurement Locations 00 o Gross Actity - Average - "+3StDev a a "-3StDev"'
0 F8130161 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm 2 45 42 39 36 c,,
33 I-.
30 U.. 27 24 LL 21 18 El I 15 12 9
6 00 3
0 C'%J Bins - Upper End Value (dpm/1 00cm2)