ML082620165

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Final Status Survey Summary Report, June 30, 2008, East Heat Removal Cooler Room Between Columns 10.3 and 9.7, Room 051 Floor and Lower Walls Survey Unit F8130691
ML082620165
Person / Time
Site: Rancho Seco
Issue date: 07/29/2008
From: Stein M
Sacramento Municipal Utility District (SMUD)
To:
NRC/FSME
References
MPC&D 08-064 F8130691
Download: ML082620165 (23)
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Text

Rancho Seco Final Status Survey Summary Report June 30, 2008 East Heat Removal Cooler Room Between Columns 10.3 and 9.7, Room 051 Floor and Lower Walls Survey Unit F8130691 Prepared y:

Date: 4o01

/

FSS Engineer Reviewed By Date:--I 08 Lead FSS Engineer Approved By:

Date: 7-

-c'8 Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8130691, East Heat Removal Cooler Room Between Columns 10.3 and 9.7, Room 051 Floor and Lower Walls Survey Unit

Description:

Operating History: The East Heat Removal Cooler Room is located on the -20' elevation of the Auxiliary Building. The Auxiliary Building is a reinforced concrete structure that, during power operations, contained the Radwaste processing and supporting systems.

The building has six main elevations. Residual levels of surface radioactivity were detected on all interior elevations 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 taken on each interior elevation of the Auxiliary Building. These measurements confirmed the presence of plant-derived radionuclides. Direct measurements taken 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/100 cm 2.

Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the interior surfaces of the Auxiliary Building were determined primarily to be a Class I for the floors and lower walls (bottom 2 meters of the walls), and Class 2 for the upper walls and ceiling. Inside the East Heat Removal Cooler Room there were a number of areas on the floor and lower walls where the gross surface activity levels were higher than the DCGL prior to remediation. Therefore, a Class 1 final status survey was performed on the floor and lower walls of the East Heat Removal Cooler Room Between Columns 10.3 and 9.7, Room 051.

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 125 m2 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 F8130691

Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area:

F813 Survey Unit:

Class:

SU Area (m2);

Evaluator:

DCGL (dpm/I oo cm2):

Area Factor:

Design DCGLemc (dpm/100 cm2):

LBGR (dpm/100 cm2):

Design Sigma (dpm/100 cm2):

Type'l Error:

Type II Error:

Predominant Nuclide:

Sample Area (mZ):

Scan Area (M2):

Scan Coverage (%):

Sign P:

Calculated Relative Shift:

Relative Shift Used:

N-Value:

Design N-Value + 20%:

Design Min Samples N:

Grid Spacing L:

0691 1

125 Michael Stein 43000 3.6 154800 21500 12035 0.05 0.05 Cs-137 6.9 125 100%

1.645 1.645 0.955435 1.7 1.7 14 17 18 2.6.

East Heat Removal Cooler Room Between Columns 10.3 and 9.7, Room 051 Floor and Lower Walls Structure Surface LTP Table 5-4 Gross-Activity DCGL Class 1 Class 1 Default = 50% DCGL Class 1 Class I Uses 3.0 if Relative Shift is

>3 NUREG-1575 Table 5-5 Class 1 Class 1 I

Page 3 of 8 PFSS Summary Repo rt F8130691

Survey Results:

A total of 18 direct measurements were made in F8130691. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. None of the scan measurements indicated areas of elevated activity. Scan activity ranged from 3,276 to 140,042 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 Activit (dpmllO0 cm F8130691-CO001BD F8130691-CO002BD F8130691-CO003BD F8130691-CO004BD F8130691-COOO5BD F8130691-CO006BD F8130691-CO007BD F8130691-CO008BD F8130691-CO009BD F8130691-Co01OBD F8130691-Co011BD F8130691-CO012BD F8130691-CO013BD F8130691-CO014BD F8130691-CO015BD F8130691-CO016BD F8130691-CO017BD F8130691-Co018BD Mean:

Median:

Standard Deviation:

Range:

7044 2739 1390 3050 1997 11609-3055 1416 4809 2677 3548 2153 1743 1862 1701 2402 1743 2018 3164 2277 2521 1390-11609 Page 4 of 8 FSS Summary Report F8130691

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

F8130691C0001SM

-4.82 F8130691C0002SM

-0.95 F8130691 C0003SM

-0.95 F8130691 C0004SM

-2.24 F8130691C0005SM

-3.53 F8130691C0006SM

-4.82 F8130691C0007SM

-0.95 F8130691C0008SM

-2.24 F8130691 C0009SM

-0.95 F8130691C0010SM

-2.24 F8130691CO01ISM 2.93 F8130691CO012SM

-3.53 F8130691C0013SM

-2.24 F8130691CO014SM

-3.53 F8130691C0015SM

-4.82 F8130691C0016SM

-3.53 F8130691C0017SM 1.64 F8130691C0018SM

-4.82 Mean:

-2.31 Median:

-2.24 Standard Deviation:

2.19 Range:

-4.82 to 2.93 Page 5 of 8 FSS Summary Report F8130691

Survey Unit Data Assessment:

The survey design required 18 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 F8130691

Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/lO0 cm2):

N/A Ambient Background Used (dpn/100 cm2):

N/A Average Ambient BKG = 0 Actual Direct Measurements (N):

18 Median (dpm/100 cm2):

2277 Mean (dpm/100 cm2):

3164 Direct Measurement Standard Deviation 2521 (dpm/100 cm2):

Total Standard Deviation (dpm/100 cm2):

2521 Based on samples and backgrounds.

Maximum (dpm/100 cm 2):

11609 Material Type:

N/A Background Subtract Not Applied Sign Test Final N Value:

18 S+ Value:

18 Critical Value:

12 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 7 of 8 FSS Summary Report F8130691

Survey Unit Investigations and Results:

No investigations were required for either direct or scan measurements and no investigation results are reported.

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. No potential areas of elevated activity were detected.

==

Conclusion:==

The FSS of this survey unit was properlydesigned 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 cm2 and none of the removable surface activity measurements exceeded 10% of the DCGL. No investigations were required.

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 F8130691 meets the release criteria of 10CFR20.1402.

Page 8 of 8 FSS Summary Report F8130691 Maps June 30, 2008 Survey Unit F8130691

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Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No.

Model; Serial No.

(dpm/100 cm2 )

(dpm/100 cm 2 )

M2350; 149789 43-68B; 161397 433 1033 M2350; 193715 43-68B; 160703 433.

1033 M2350; 149789 43-116-1B; 256006 491 3 Junctures 739 3 Junctures M2350; 193715 43-116-1B; 190643 796 3258 M2350; 175834 43-116-1B; 190642 491 13 Junctures 739 P3 Junctures Tennelec; 0401171 N/A 5.9dpmu, N/A 11.7 dpm [_

The scan and static MDC's provided represent the most conservative MDC values for the survey conducted.

Table 2-2. Investigation Criteria and DCGL Value Parameter Value cm2)

(dpm/100 c2 Investigation Criteria - Direct 154800 Investigation Criteria - Scan 154800 DCGLw 43000 DCGLEMc 154800 Page 2 of 2 Att. 2 Instrumentation F8130691 Investigation June 30, 2008 Survey Unit F8130691 (none required)

Data Assessment June 30, 2008 Survey Unit F8130691.

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00 F8130691 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm2 I

14,000 12,000 10,000 8,000 6,000 4,000 2,000 0

2277

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