ML082620161

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Final Status Survey Summary Report, July 8, 2008, Pump Alley North and East Walls Below -25'9, Survey Unit F8130441
ML082620161
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 F8130441
Download: ML082620161 (24)
v • d • e


Text

Rancho Seco Final Status Survey Summary Report July 8, 2008 Pump Alley North and East Walls below -25'9" Survey Unit F8130441 Prepared By: Dan A. Tallman Date: July 8, 2008 FSS Enginee Reviewed By: -IDate: 7/3:9/0,5 Lead FSS Engineer Approved By: 5.7 Date: 7-30 -0

  • Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8130441, Pump Alley North and East Walls below -25'9" 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 -29' elevation showed a mean gross activity level of 544,756 dpm/100 cm 2 and a maximum value of 11,370,000 dpmr/100 cm 2 . Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the north and east walls of Pump Alley below 25'9" were 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 165 m2 were scanned for 100%1 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 F8130441

Table 1. Survey Unit Design Parameters Survey Design Value Comment

. Parameter Survey Area: F813 Pump Alley North and East Walls below -25'9" Survey Unit: 0441 Structure Surface Class: 1 LTP Table.5-4 SU Area (m2): 164.6 Evaluator:

D.A.Tallman DCGL (dpm/100 cm 2): 43000 Gross Activity DCGL Area Factor: 3.5 Class 1 Design DCGLemc 154285 Class 1 (dpm/100 cm 2):

LBGR (dpm/IO0 cm 2): 21500 Default = 50% DCGL 2

Design Sigma (dpm/100 cm ): 10204 Type I Error: 0.05 Type Ii Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): 6.86 Class I 2 165 Scan Area (m ):

Scan Coverage (%): 100% Class 1 Zl_*t :

1.645 ZI-0 : 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: 24 Class 1 Grid Spacing L: 2.6 Class 1 Page 3 of 9 FSS Summary Report F8130441

Survey Results:

A total of 39 direct measurements were made in F8130441. 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 1966 to 666520 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.

Page 4 of 9 FSS Summary Report F8130441

Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/100 cm F8130441-CO001BD 1509 F8130441-C0002BD 1344 F8130441-CO003BD 1525 F8130441-CO004BD 1478 F8130441-COOO5BD 1587 F8130441-CO006BD 1681 F8130441-CO007BD 1608 F8130441 -CO008BD 1940 F8130441-CO009BD 1660 F8130441-COOIOBD 1582 F8130441-Co011BD 1608 F8130441-CO012BD 1660 F8130441-CO013BD 1624 F8130441-Co014BD 1707 F8130441-Co015BD 1525 F8130441-Co016BD 1587' F8130441-Co017BD 1779 F8130441-Co018BD 2822 F8130441-Co019BD 1655 F8130441 -CO02OBD 2588 F8130441 -C0021 BD 1556 F8130441-CO022BD 1618 F8130441-CO023BD 2282 F8130441-CO024BD 1748 F8130441-CO025BD 1655 F8130441-CO026BD 1701 F8130441-CO027BD 2594 F8130441-CO028BD 1598 F8130441-CO029BD 2148 F8130441-CO03OBD 1935 F8130441 -C0031 BD 2734 F8130441 -Co032BD 1826 F8130441-CO033BD 1733 F8130441-CO034BD 1727 F8130441-C0035BD 1935 F8130441-C0036BD 1738 F8130441-CO037BD 1779 F8130441 -CO038BD 3823 F8130441-CO039BD 4124 Mean: 1916 Median: 1701 Standard Deviation: 598 Range: 1344-4124 Page 5 of 9 FSS Summary Report F8130441

Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)

F8130441CO001SM -3.53 F8130441CO002SM -2.24 F8130441 C0003SM -3.53 F8130441 C0004SM -2.24 F8130441CO005SM 1.64 F8130441 C0006SM -0.95 F8130441 C0007SM -4.82 F8130441 C0008SM -4.82 F8130441 C0009SM 0.34 F8130441CO010SM 0.34 F8130441CO01ISM -2.24 F8130441CO012SM -3.53 F8130441CO013SM -2.24 F8130441CO014SM -3.53 F8130441CO015SM -2.24 F8130441CO016SM -3.53 F8130441CO017SM 2.93 F8130441 COO 18SM -3.53 F8130441CO019SM -4.82 F8130441 C0020SM -4.82 F8130441 C0021 SM -3.53 F8130441CO022SM -2.24 F8130441 C0023SM 1.64 F8130441 C0024SM -2.24 F8130441 C0025SM 0.34 F8130441,C0026SM -0.95 F8130441 C0027SM -2.24 F8130441CO028SM -4.82 F8130441 C0029SM 2.93 F8130441 C0030SM -2.24 F8130441C0031SM 0.34 F8130441 C0032SM -3.53 F8130441C0033SM 0.34 F8130441 C0034SM 0.34 F8130441CO035SM -3.53 F8130441CO036SM -0.95 F8130441 C0037SM 55.88 F8130441 C0038SM 18.42 F8130441 C0039SM 4.22 Mean: 0.28 Median: -2.24 Standard Deviation: 9.97 Range: -4.82 to 55.88 Page 6 of 9 FSS Summary Report F8130441

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 F8130441

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): 39 Median (dpm/100 cm 2): 1701 Mean (dpm/100 cm2): 1916 Direct Measurement Standard Deviation 598 (dpm/100 cm 2):

Total Standard Deviation (dpm/100 cm 2): 598 Based on samples and backgrounds.

Maximum (dpm/100 cm 2): 4124 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 F8130441

Survey Unit Investigations and Results:

Fifteen (15) investigations (scan grids 01, 21, 43, 93, 94, 95, 157, & 164 plus scan junctures 025BS, 08GS, 09GS, 1IGS, 21GS, 22GS, & 23GS) 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. 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/t00 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 F8130441 meets the release criteria of 10CFR20.1402.

Page 9 of 9 FSS Summary Report F8130441

Attachment I Maps July 8, 2008 Survey Unit F8130441

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INTERFACE

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Attachment 2 Instrumentation July 8, 2008 Survey Unit F8130441

Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No. Model; Serial No. (dpm/100 cm2 ) (dpmll00 cm2 )

M2350; 193715 43-68B; 148630 433 1033 M2350; 193715 43-116-IB; 190643 796 3258 Tennelec; 0401171 N/A 6 dpm , 12 dpm3 N/A Instrument Detector MDC Model; Serial No. Model; Serial No. (dpmll00 cm2 )

M2350; 203481 44-10; 171992 167561 13,900 (Co60)

InSpector 1000 08051294 27,700 (Cs137)

'Background 8000 cpm or less Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2)

Investigation Criteria - Direct 154285 Investigation Criteria - Scan 1,2 154285 DCGLw 43000 DCGLEMc 154285 Investigation level for gamma scan (44-10) of moisture barrier and concrete soil interface/junctures set at - 9100 cpm 2 Investigation level for beta scan measurements set conservatively at DCGLw within the survey instruction package.

Page 2 of 2 Att. 2 Instrumentation F8130441

Attachment 3 Investigation July 8, 2008 Survey Unit F8130441

Table 3-1 Survey Unit Investigation Gnd ~ Investigation Result Investigation Initial Value Investigation Area (in 2) Factor Investigation

/lcm) d Result DCGLemc Fato Elevated Area DCGLemc Unity Level (cpm) (cpm) (cpm) A (m2) Factor_(dpm/lOOcm2) Fraction 01BS 5840 7548 7548 0.13 101.9 4379980 55372 0.012 21BS 5840 5848 5848 1.0 14.9 640700 I 42901 0.064 43BS .5840 6222 6222 0.08 164.2 7058450 45644 0.006 93BS 5840 7190 7190 0.280 48.4 2080340 52746 0.024 94BS 5840 8938 8938 0.08 164.2 7058450 65569 0.009 95BS 5840 5891 5891 0.05 261.4 11241920 [ 43216 1 0.004 157BS 5840 8963 8963 0.41 33.8 1455120 65752 0.044 164BS 5840 6840 6840 0.16 83.2 3576310 50178 0.013 J25BS 19 9 0 d 2309 2309 0.01 1294.1 55646300 52523 0.001 J08GS 10000 12712 a 0. 0 5 1 b 256 11025200 282000c 0.026 J09GS 10000 11893 a 0.051 b 256 11025200 141000c 0.013 J11GS 10000 15758 a 0 .0 5 1b 256 I 11025200 289000c 0.026 J21GS 10000 16663 a 0. 0 5 1 b 256 11025200 274500c 0.025 J22GS____ 10000 10363 a .

0 05 1b 256 11025200 214800c 0.019 J23GS 1 10000 1 9548 F- a 0. 0 5 1 b 256 11025200 185000c 0.017 0

Comments:

a Investigation results from InSpector 1000 measurement (no cpm values listed - see Investigation results - dpm/100 cm 2) 2 b Assumes 1" by 79" "juncture" (actual seal dimension is - 0.5 cm

  • 2 meters - 0.01 M ).

2 c Calculated from InSpector 1000 measurement and assumes the entire seal surface area contaminated at this level vs detector FOV of 16.5 cm d Concrete Structure Scan Investigation Level and efficiencies used based on post remediation geometry of juncture surfaces Survey Unit Remainder DCGL = SU Mean = 0.045 43,000 1916 EMC Unity Sum 0.348 Page 2 of 2 Att. 3 Investigation F8130441

Attachment 4 Data Assessment July 8, 2008 Survey Unit F8130441

F81 30441 Gross Activity Sample Results Quantile Plot 2

0 DCGL = 43000 dpm/1 00cm 4,500 4,000 3,500 3,000 2,500 I 2,000 CD 1701 1,500 CD 1,000 500 0

0 20 40 60 80 100 Percentile 00 I

  • Direct Measurements (dpm/l0Ocm2) -median - -.. 75th Percentile ---- 50th Percentile I

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00 FB130441 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpm/l00cn=

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F8130441 Gross Activity Frequency Plot 2

DCGL = 43000 dpm/1 00cm 28 26 24 22 20 18 C

16 14 00 0

12 10 8

6 4

t-j) 2 0

N- (14It Bins - Upper End Value (dpm/1 00cm2)

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