ML082620117
| ML082620117 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 06/16/2008 |
| From: | Tallman D Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-064 | |
| Download: ML082620117 (12) | |
Text
Rancho Seco Final Status Survey Summary Report (Rev.1)
June 16, 2008 RC Drain Tank (V-600) Room (lowers)
Survey Unit F8130051 Prepared By: Dan A. TallmE an Date: June 16, 2008 FSS Engineer Reviewed By: >'*Q Date: 7 f1 60 Lead FSS Engineer Approved By: Date: ______
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8130051, RC Drain Tank (V-600) Room (lowers)
Survey Unit
Description:
Operating History: The Auxiliary Building was a reinforced concrete structure which 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 cm 2 and a maximum value of 5,720,000 dpm/100 cm2 . Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the Reactor Coolant Drain Tank (V-600) room within the interior of the auxiliary building was determined to be a Class 1 survey unit.
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 141 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 8 FSS Summary Report F8130051
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F813 RC Drain Tank (V-600)
Room (lowers)
Survey Unit: 0051 Structure Surface Class: 1 LTP Table 5-4 SU Area (m): 141 Evaluator: D.A.Tallman DCGL (dpm/100 cm2): 43000 Gross Activity DCGL Area Factor: 3.6 Class 1 Design DCGLemc 156520 Class 1 2
(dpm/100 cm ):
LBGR (dpm/100 cm2): 21500 Default = 50% DCGL Design Sigma (dpm/100 cm 2): 9976 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): 6.7 Class 1 Scan Area (m2 ): 141 Scan Coverage (%): 100% Class 1 Zl-,t "- 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: 21 Class 1 Grid Spacing L: 2.5 Class 1 Page 3 of 8 FSS Summary Report F8130051
Survey Results:
A total of 26 direct measurements were made in F8130051. 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 1922 to 189618 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 (dpmll00 cm F81'30051-COOOIBD 2422 F8130051-C0002BD 2148 F8130051-C0003BD 1982 F8130051-CO004BD 1707 F8130051-CO005BD 1644 F8130051-C0006BD 1971 F8130051-CO007BD 27664 F8130051-C0008BD 2324 F8130051-CO009BD 1608 F8130051-COOIOBD 1790 F8130051-CO011BD 1733 F8130051-CO012BD 1769 F8130051-CO013BD 1779 F8130051-C0014BD 1940 F8130051-Co015BD 7221 F8130051-CO016BD 2293 F8130051-CO017BD 2013 F8130051-CO018BD 4565 F8130051-CO019BD 2760 F8130051-CO02OBD 5493 F8130051-CO021BD 3138 F8130051-CO022BD 2557 F8130051-CO023BD 2028 F8130051-CO024BD 2314 F8130051-CO025BD 2843 F8130051-CO026BD 2848 Mean: 3560 Median: 2220 Standard Deviation: 5084 Range: 1608 - 27664 Page 4 of 8 FSS Summary Report F8130051
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpml100 cm 2 )
F8130051C0001SM 11.97 F8130051 C0002SM 4.22 F8130051 C0003SM 1.64 F8130051 C0004SM 9.38 F8130051COOO5SM 4.22 F8130051 C0006SM 2.93 F8130051 C0007SM -2.24 F8130051CO008SM 32.63 F8130051 C0009SM 8.09 F8130051Co010SM 4.22 F8130051CO011SM 126.91 F8130051CO012SM 11.97 F8130051C0013SM 14.55 F8130051CO014SM 70.08 F8130051COO15SM -0.95 F8130051CO016SM 4.22 F8130051Co017SM -0.95 F8130051Co018SM 17.13 F8130051Co019SM 28.76 F8130051CO020SM 21.01 F8130051C0021SM 2.93 F8130051 C0022SM 1.64 F8130051 C0023SM 48.13 F8130051 C0024SM 32.63 F8130.051 C0025SM 10.68 F8130051C0026SM 1.64 Mean: 17.98 Median: 8.74 Standard Deviation: 27.92 Range: -2.24 to 126.91 Page 5 of 8 FSS Summary Report F8130051
Survey Unit Data Assessment:
The survey design required 26 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 6 of 8 FSS Summary Report F8130051
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm2): N/A Ambient Background Used (dpm/100 cm 2 ): N/A Average Ambient BKG = 0 Actual Direct Measurements (N): 26 Median (dpm/100 cm 2): 2220 Mean (dpm/100 cm 2): 3560 Direct Measurement Standard Deviation 5084 2
(dpm/100 cm ):
Total Standard Deviation (dpm/100 cm 2 ): 5084 Based on samples and backgrounds.
Maximum (dpm/100 cm 2): 27664 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 26 S+ Value: 26 Critical Value: 17 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 7 of 8 FSS Summary Report F8130051
Survey Unit Investigations and Results:
Six (6) investigations (scan grids 019, 143, 145, Junctures 02, & 42, and Penetration 02) 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.
During routine surveillance surveys utilizing the 44-10 Nal detector, discovery was made in grids 14, 33, 36, 51, 61, and 71. The results of this discovery are detailed in Revision 1 to Attachment 3. The EMC unity rule was not exceeded as shown in Revision 1 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 demonstrating that 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
-ofthe 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 F8130051 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F8130051
Attachment 2 (Rev. 1)
Instrumentation June 16, 2008 Survey Unit F8130051
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; 203481 43-68B; 161405 M2350; 142507 43-68B; 160781 433 1033 M2350; 193715 43-68B; 160703 M2350; 149789 43-116-1B; 256006 796 3258 M2350; 193715 43-116-1B; 190643 M2350; 149789 43-116-iB; 256006 4911 10601 M2350; 193715 43-116-1B; 190643 M2350; 203482 44-10; 211672 M2350; 203486 44-10; 171995 Tennelec; 0401171 N/A 16 dpm a 12 dpmfl N/A 43-116-lB - Juncture Scan - concrete Table 2-2. Investigation Criteria and DCGL Parameter Value VleC2 (dpm/100 cm 2 )
Investigation Criteria - Direct 156520 Investigation Criteria - Scan 43000 1,2 DCGLw 43000 DCGLEMC 156520 Scan Investigation Level set at DCGLw 2 Scan Investigation Level for routine 44-10 surveillance scan set at 20,000 cpm Page 2 of 2 Att. 2 Instrumentation F8130051
Attachment 3 (Rev. 1)
Investigation June 16, 2008 Survey Unit F8130051 Page I of 2 Ant. 3 Investigation F8130051
Table 3-1 Survey Unit Investigation Investigation Investigation DCGLemc Grid Investigation Initial Value Result Elevated Area DCGLenc Result Unity Level (cpm) (cpm) (cpm) Area (m2) Factor (dpmDROOcm2) Fraction Grid 19 1990* 2154 1723 NA NA NA NA 0 Grid 145 5840 25848 13262 0.22 60.95 2,620,881 153,584 0.056 Grid 143 5840 13468 5919 0.04 326 14,022,374 68547 0.005 J-42 4260 4529 5515 0.02 649 27,913,730 63868 0.002 J-02 1990* 3031 2498 NA NA NA NA 0 P-02 1990* 2013 2013 0.4 34.65 1,489,303 43380 0.025 G14 20000 44000 44000 0.02 559.7 24,067,100 1,707,808 0.071 G33 20000 37000 37000 0.05 280.9 12,079,990 1,436,111 0.119 G36 20000 35000 35000 0.01 1294.1 55,646,300 1,358,483 0.024 G51 20000 30000 30000 0.01 1294.1 55,646,300 1,164,414 0.021 G61 20000 48000 48000 0.01 1294.1 55,646,300 1,863,063 0.034 G71 20000 37000 37000 0.01 1294.1 55,646,300 1,436,111 0.026 Investigation Level as documented within the survey instructions = 1100 cpm above background. Subsequent to survey performance, the IL was revised to the 1990 value based on the scan speed coefficient modification (0.42 vs. 0.76)
During routine surveillance surveys using the 44-10 (Nal), discovery was made within grids 14, 33, 36, 51, 61, &71.
Survey Unit Remainder DCGL= SU Mean 0.144 43,000 6194 EMC Unity Sum 0.526 Page 2 of 2 Att. 3 Investigation F8130051