ML082620164

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Final Status Survey Summary Report, June 01, 2008, AB - Pump Alley Column 11.7 South Above -25'7 Elevation Survey F8130471
ML082620164
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 F8130471
Download: ML082620164 (28)
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Text

Rancho Seco Final Status Survey Summary Report July 1, 2008 AB - Pump Alley column 11.7 south above -25'7" elevation Survey Unit F8130471 Prepared By: Dan A. Tallman Date: July 2, 2008 FSS Engineer Reviewed By: Date:

Lead FSS Engineer Approved By: e<- e Date: 7-3 0 Fo Dismantlement Sbperintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8130471, AB - Pump Alley column 11.7 south above -25'7" elevation 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/1 00 cm 2 and a maximum value of 11,370,000 dpm/100 Cm2 . Based on the classification procedure (DSIP-0020) and levels of gross activity reported, Survey Unit 813047, 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 280.9 m2 were scanned for 100% coverage. Samples of removable contamination were collected at each direct ineasurement 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 F8130471

Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F813 AB - Pump Alley column 11.7 south above -257" elevation Survey Unit: 0471 Structure Surface Class: 1 LTP Table 5-4 SU Area (m2): 280.9 Evaluator: D.A.Tallman DCGL (dpm/100 cm'): 43000 Gross Activity DCGL Area Factor: 3.5 Class I Design DCGLemc 154370 Class 1 (dpm/100 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): 6.85 Class 1 Scan Area (M2 ): 280.9 Scan Coverage (%): 100% Class I ZI., : 1.645 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: 41 Class 1 Grid Spacing L: 2.6 Class 1 Page 3 of 9 FSS Summary Report F8130471

Survey Results:

A total of 43 direct measurements were made in F8130471. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. Two of the scan measurements indicated areas of elevated activity. Beta Scan activity ranged from 2409 to 12410 dpm/100 cm2 , based on a surveyor efficiency of 0.5 and no background subtracted. In-vivo gamma scans of two grids (13 and 49) exceeded the investigation level with observed activities of 71,800 dpmr100 cm 2, and 68,600 dpm/100 cm 2 respectively. 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 F8130471

Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/lO0 cm F8130471-CO001BD 1888 F8130471-CO002BD 2039 F8130471-CO003BD 1561 F8130471-CO004BD 1764 F8130471-CO005BD 1364 F8130471-CO006BD 1302 F8130471-CO007BD  ? 4648 F8130471 -CO008BD 2563 F8130471 -CO009BD 1836 F8130471-Co01OBD 3128 F8130471-CO011BD 2277 F8130471-Co012BD 1841 F8130471-Co013BD 3185 F8130471-Co014BD 1940 F8130471-Co015BD 1867 F8130471-Co016BD 1914 F8130471-Co017BD 1826 F8130471-CO018BD 1758 F8130471-CO019BD 2199 F8130471-CO02OBD 1727 F8130471-C0021 BD 1582 F8130471-CO022BD 1847 F8130471-CO023BD 1862 F8130471-CO024BD 1385 F8130471-CO025BD 1561 F8130471-CO026BD 2075 F8130471-CO027BD 1608 F8130471-CO028BD 1769 F8130471-CO029BD 1722 F8130471-CO03OBD 1484 F8130471-CO031BD 1930 F8130471-CO032BD 1826 F8130471-CO033BD 1644 F8130471 -CO034BD 2552 F8130471-CO035BD 2153 F8130471-CO036BD 1743 F8130471-CO037BD 4274 2557 F8130471-CO039BD 4082 F8130471-CO04OBD 2910 F8130471-CO041BD 2324 F8130471-Cc042BD 6795 F8130471-CO043BD 3377 Mean: 2272 Median: 1867 Standard Deviation: 1045 Range: 1302-6795 Page 5 of 9 FSS Summary Report F8130471

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

F8130471 COOOI SM -2.24 F81 30471 C0002SM -0.95 F8130471CO003SM -3.53 F8130471 C0004SM -0.95 F8130471 COOO5SM 6.8 F8130471CO006SM -2.24 F8130471 C0007SM 301.25 F8130471CO008SM 42.96 F8130471CO009SM 10.68 F8130471Co010SM 6.8 F8130471CO01ISM 14.55 F8130471CO012SM 4.22 F8130471CO013SM 37.8 F8130471CO014SM 21.01 F8130471CO015SM 11.97 F8130471CO016SM 72.67 F8130471CO017SM 128.2 F8130471CO018SM 27.46 F8130471C0019SM 94.62 F8130471 C0020SM 26.17 F8130471C0021SM 5.51 F8130471 C0022SM 45.55 F8130471CO023SM 11.97 F8130471CO024SM -0.95 F8130471C0025SM 10.68 F8130471CO026SM 77.83 F8130471 C0027SM 4.22 F8130471 C0028SM 4.22 F8130471 C0029SM 1.64 F8130471 C0030SM 26.17 F8130471C0031SM 1.64 F8130471 C0032SM 73.96 F8130471 C0033SM 39.09 F8130471C0034SM 4.22 F8130471 C0035SM 6.8 F8130471CO036SM 32.63 F8130471C0037SM 0.34 F8130471C0038SM 15.84 F8130471 C0039SM 24.88 F8130471 C0040SM 22.3 F8130471 C0041SM 8.09 F8130471 C0042SM -0.95 F8130471 C0043SM 9.38 Mean: 28.43 Median: 10.68 Standard Deviation: 51.46 Ranqe: -3.53 to 301.25 Page 6 of 9 FSS Summary Report F8130471

Survey Unit Data Assessment:

The survey design required 43 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.

SPage 7 of 9 FSS Summary Report F8130471

Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm 2): N/A Ambient Background Used (dpm/100 cm2): N/A Average Ambient BKG 0 Actual Direct Measurements (N): 43 Median (dpm/100 cm 2): 1867 Mean (dpm/l00 cm 2): 2272 Direct Measurement Standard Deviation 1045 (dpm/100 cm 2):

Total Standard Deviation (dpm/100 cm 2): 1045 Based on samples and backgrounds.

Maximum (dpm/100 cm 2): 6795 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 43 S+ Value: 43 Critical Value: 27 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 F8130471

Survey Unit Investigations and Results:

Two (2) investigations (scan grids GS 13 and GS49) 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 F8130471 meets the release criteria of 10CFR20.1402.

Page 9 of 9 FSS Summary Report F8130471

Attachment 1 Maps July 1, 2008 Survey Unit F8130471

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Attachment 2 Instrumentation July 1, 2008 Survey Unit F8130471

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

M2350; 149789 43-68B; 161397 433 1033 M2350; 149789 43-116-1B; 256006 A 437 739 Tennelec; 0401171 N/A 6 dpm a,12 dpm "N/A

-3 A Juncture Detector MDC I Instrument (dpm/100 cm=)

Model; Serial No. Model; Serial No.

1580 (Co60)

ISOCS 1983920 1400 (Cs 137) 3920_2mconcrete geometry 12.5 m2 FOV Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2 )

Investigation Criteria - Direct 154370 Investigation Criteria - Scan 154370 DCGLw 43000 DCGLEMc 154370 Value (dpm/100 cm 2 )

To detect a 1 m hot spot at the EMC Criterion within the detector field of view 63,300 dpm/100 cm 2 Cs-137 21,275 dpm/100 cm 2 Co-60 3920_2mconcrete geometry 12.5 m2 FOV 2 Investigation Level set at 43,000 dpm/lOOcm 2 Cs-137, ND Co-60 for investigation within survey instructions, revised during data evaluation based on LFSSE recommendation.

Page 2 of 2 Att. 2 Instrumentation F8130471

Attachment 3 Investigation July 1, 2008 Survey Unit F8130471

Table 3-1 Survey Unit Investigation Inigoal Investigation Elevated Investigation -DCGLemrc Grid Investigation (dpValuem Result Area Area/10 Factor DCGLemc Result Unity Level (dpm/cm0 cm)) (dpm/100 (cpm) (M 2) (dpm/l OOcm 2) Fraction ICM2)

________ j 2

GS13 63,300 dpm/100 cm 75,8003 1,5552 NA NA NA 11,4061 NA

.Cs-137 GS49 21,275 dpm/100 cm 2 71,8003 1,5573 NA NA NA 11,4192 NA Co-60 Comments:

1Average of BS01-05 taken within boundaries of elevated measurement.

2 Average of BS06-10 taken within boundaries of elevated. measurement.

3 Total activity as calculated on F8130471 - Scan Sample Results worksheet (Co60/Csl37 summation)

Survey Unit Remainder DCGL = SU Mean = 0.053 43,000 2,272 EMC Unity Sum 0.053 Page 2 of 2 Att. 3 Investigation F8130471

Attachment 4 Data Assessment July 1, 2008 Survey Unit F8130471

GO F8130471 Gross Activity Sample Results Quantile Plot CD DCGL = 43000 dpm/1 00cm2 8,000 7,000 6,000 I 5,000 4,000 3,000 2,000 1867 1,000 0 -,F 0 20 40 60 80 100 Percentile 0

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  • Direct Measurements (dpm/ll00cm2) - median - - 75th Percentile - -- - 50th Percentile

0Q F8130471 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpml00cm2 ,

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