ML090980390

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Final Status Survey Summary Report, October 8, 2008 East Heat Removal Cooler Room North of Column 9.1, Room 051 Floor, Walls, and Ceiling Survey Unit F8130731
ML090980390
Person / Time
Site: Rancho Seco
Issue date: 10/08/2008
From:
Sacramento Municipal Utility District (SMUD)
To:
NRC/FSME
Shared Package
ML090830613 List: ... further results
References
DPG 09-097
Download: ML090980390 (26)
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Rancho Seco Final Status Survey Summary Report October 8, 2008 East Heat Removal Cooler Room North of Column 9.1, Room 051 Floor, Walls, and Ceiling Survey Unit F8130731 Prepared By:

Date:

,,20 FSS Engineer Reviewed By:

Date:

t3 O0 Lead FSS Engineer Approved By:

Z,

2.Date

2'4 -

Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8130731, East Heat Removal Cooler Room North of Column 9.1, Room 051 Floor, Walls, and Ceiling 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/1 00 cm2 and a maximum value of 10,080,000 dpm/l100 cm2. "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 1 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 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, walls, and ceiling of the East Heat Removal Cooler Room North of Column 9.1.

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 142 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 F8130731

Table 1. Survey Unit Design Parameters Survey Design.

Value Comment Parameter Survey Area:

F813 Survey Unit:

Class:

SU Area (m2):

Evaluator:

DCGL (dpm/100 cm 2):

Area Factor:

Design DCGLemc (dpm/100 cm 2):

LBGR (dpm/100 cm2):

Design Sigma (dpm/100 cm 2):

Type I Error:

Type II Error:

Predominant Nuclide:

Sample Area (m2):

Scan Area (m):

Scan Coverage (%):

Zl-, :

Zl-I0 :

Sign P:

Calculated Relative Shift:

Relative Shift Used:

N-Value:

Design N-Value + 20%:

Design Min Samples N:

Grid Spacing L:

0731 1

142 Michael Stein 43000 3.6 154800 21500 12035 0.05 0.05 Cs-137 6.8 142' 100%

1.645 1.645 0.955435 1.7 1.7 14 17 21 2.6 East Heat Removal Cooler Room North of Column 9.1, Room 051 Floor, Walls, and Ceiling Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class 1 Default = 50%.DCGL Class I I Class 1 Uses 3.0 if Relative Shift is

>3 NUREG-1575 Table 5-5 Class 1 Class 1 Page 3 of 8 FSS Summary Report F8130731

Survey Results:

A total of 23 direct measurements were made in F8130731. 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 beta scan measurements (COI 12BS and CO 116BS) indicated areas of elevated activity as shown in Attachment 3. Scan activity ranged from 645 to 293,443 dpm/100 cm2, based on a surveyor efficiency of 0.5 and no background subtracted. Four of the gamma scan measurements taken in the recess area around reactor wall penetrations (C0007GS, COO1OGS, COO IGS, CO012GS, and COOI7GS) indicated areas of elevated activity as shown in Attachment 3. Gamma scan activity ranged from 37,587 to 461,140 dpm/100 cm2 Cs-137. Only two of the gamma scan measurements detected Co-60 at 9,900 and 10,604 dpm/100 cm2. The MDCs for the gamma scan measurements were 4,630 to 5,428 dpm/100 cm 2 for Co-60 and 4,410 to 12,400 dpm/100 cm 2 for Cs-137. Scan measurement locations for both beta and gamma emissions are identified in Attachment 1 of this report. 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 (dpm/100 cm F8130731-C0001BD 1950 F8130731-C0002BD 1852 F8130731-C0003BD 1779 F8130731-CO004BD 2614 F8130731-CO005BD 2132 F8130731-CO006BD 3953 F8130731-C0007BD 2635 F8130731-C0008BD 1805 F8130731-C0009BD 1758 F8130731-CO010BD 1561 F8130731-CO011BD 1784 F8130731-CO012BD 1655 F8130731-CO013BD 1696 F8130731-CO014BD 1722 F8130731-CO0o15BD 1707 F8130731-CO016BD 4508 F8130731-CO017BD 1681 F8130731-CO018BD 1551 F8130731-CO0o19BD 1608 F8130731-C0020BD 1541 F8130731-C0021 BD 2085 F8130731-CO022BD 1816 F8130731-CO023BD 1758 Mean:

2050 Median:

1779 Standard Deviation:

751 Range:

1541 -4508 Page 4 of 8 FSS Summary Report F8130731

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

F8130731C0001SM

-0.95 F8130731 CQ002SM 2.93 F8130731C0003SM 0.34 F8130731C0004SM 2.93 F8130731C0005SM 0.34 F8130731 C0006SM 4.22 F8130731C0007SM 18.42 F8130731 C0008SM 1.64 F8130731C0009SM 1.64 F8130731C0010SM

-0.95 F8130731C0011SM 27.46 F8130731 C001 2SM 52 F8130731C0013SM 13.26 F8130731C0014SM

-4.82 F8130731C0015SM

-0.95 F8130731C0016SM 265.09 F8130731C0017SM 27.46 F8130731C0018SM 37.8 F8130731C0019SM

-0.95 F8130731C0020SM 8.09 F8130731C0021SM 36.5 F8130731 C0022SM 13.26 F8130731 C0023SM

-3.53 Mean:

21.79 Median:

2.93 Standard Deviation:

55.25 Range:

-4.82 to 265.09 Page 5 of 8 FSS Summary Report F8130731

Survey Unit Data Assessment:

The survey design required 21 direct measurements for the Sign Test. In actuality 23 direct measurements were obtained. 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 F8130731

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):

23 Median (dpm/100 cm2):

1779 Mean (dpm/100 cm2):

2050 Direct Measurement Standard Deviation 751 (dpm/100 cm2):

Total Standard Deviation (dpm/100 cm2):

751 Based on samples and backgrounds.

Maximum (dpm/100 cm2):

4508 Material Type:

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

23 S+ Value:

23 Critical Value:

15 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 F8130731

Survey Unit Investigations and Results:

An investigation was required for two of the beta scan measurements (CO I12BS and

  • CO 1l6BS) as indicated in Attachment 3. Investigation of these two areas resulted in the decision to perform additional remediation. The investigation results in Attachment 3 represent the residual beta radioactivity levels achieved after additional remediation. An investigation was also required for four of the gamma scan measurements taken in the recess area around reactor wall penetrations (COO07GS, COOIOGS, COO I1GS, COO12GS, and COO 17GS) indicated 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 cm2 and none of the removable surface activity measurements exceeded 10% of the DCGL.

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 F8130731 meets the release criteria of 10CFR20.1402.

Page 8 of 8 FSS Summary Report F8130731 Maps October 8, 2008 Survey Unit F8130731

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.IIF:FT I OF TC HILL nwl 813000 02 SHE 1 OF 1 Instrumentation October 8, 2008 Survey Unit F8130731

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

Model; Serial No.

(dpm/100 cm 2 )

(dpm/100 cm 2 )

M2350; 149789 43-68B; 161397 433 1033 M2350; 175834 43-68B; 148634 433 1033 M2350; 180738 43-68/5B; 148942 433 1033 M2350; 149789 43-116-1B; 256006 796 3258 M2350; 180738 43-116-1B; 216073

  • 796 3258 M2350; 193715 43-116-1B; 190643 796 3258 Tennelec; 0401171 N/A 5.9 dpm a, N/A 11.7 dpm 13 12400 Cs-137 InSpector 1000 10054579 N/A 12400 Cs-6)

,5428 Co-60 The scan and static MDC's survey conducted.

provided represent the most conservative MDC values for the Table 2-2. Investigation Criteria and DCGL Value Parameter Val ue cm 2)

(dpm/100 c2 Investigation Criteria - Direct 154800 Investigation Criteria - Scan 154800 DCGLw 43000 DCGLEMC 154800 Page 2 of 2 Att. 2 Instrumentation SF8130731 Investigation October 8, 2008 Survey Unit F8130731

Table 3-1 Survey Unit Investigation Investigation Initial Value Investigation Elevated Area Investigation DCGLemc inves iniia AreArea DCGLemc Result Unity (cpm)

(M2),

Factor (dpm/lOOcm2)

Fraction C0112BS 21,024 40,001 879 N/A N/A N/A 6,580 0.00 C0116BS 21,024 26,273 788 N/A N/A N/A 5,781 0.00 Higher Investigation Investigation Elevated Activity Initial Initial Value Area Value or Grid Level Result Area DCGLe Ino (dpm/lOOcm2) (dpm/l0Ocm2) (dpm/lOOcm2)

(m 2)

Factor Investigation Result (dpm/l 00cm2)

C0007GS 154,800 461,140 445,511 0.11 119 5,117,000 461,140 0.09 C0010GS 154,800 320,415 299,836 0.11 119 5,117,000 320.,415 0.06 C0011GS 154,800 449,060 339,820 0.07 187 8,041,000 449,060 0.06 C0012GS 154,800 161,965 138,370 0.07 187 8,041,000 161,965 0.02 C0017GS 154,800 165,817 182,709 0.05 261 11,223,000 182,709 0.02 S

DCGL =

SU Mean =

Surv ey Unit Remainder 43,000 2,050 0.05 EMC Unity Sum 0.30 All of the grids above were initially greater than DCGLemc. Investigation of grids C01 12BS and C01 16BS resulted in the decision to perform additional remediation. The investigation results above represent the residual radioactivity levels after additional remediation. No additional remediation was performed at the elevated gamma scan measurement locations C0007GS, COOOGS, C0011GS, C0012GS, and C0017GS.

Page 2 of 2 Att. 3 Investigation F8130731 Data Assessment October 8, 2008 Survey Unit F8130731

CD F8130731 Gross Activity Sample Results Quantile Plot

~o DCGL = 43000 dpm/1 00cm2 5,000 t..

4,500 4,000 S3,500

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F8130731 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmllO0cm' 5000 NE E) 4000-3000 -

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