ML082620158

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Final Status Survey Summary Report, June 19, 2008, AB -20 Corridor Column T - East, Survey Unit F8130171
ML082620158
Person / Time
Site: Rancho Seco
Issue date: 07/29/2008
From: Tallman D
Sacramento Municipal Utility District (SMUD)
To:
NRC/FSME
References
MPC&D 08-064 F8130171
Download: ML082620158 (28)
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Text

Rancho Seco Final Status Survey Summary Report June 19, 2008 AB-20' corridor column T - east Survey Unit F8130171 Prepared By: Dan A. Tallman Date: June 19, 2008 FSS Engine r Reviewed By:

Date: Cy )z3 (V*

Lead FSS Engineer Approved By:

Date:

7'O Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8130171, AB -20' corridor column T - east 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. The direct measurements 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. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the -20' corridor east of column T 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 310 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 9 FSS Summary Report F8130171

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

Survey Unit:

Class:

SU Area (m2):

Evaluator:

DCGL (dpm/100 cm'):

Area Factor:

Design DCGLemc (dpm/100 cm2):

LBGR (dpm/100 cm2):

Design Sigma (dpm/100 cm 2):

Type I Error:

Type II Error:

Predominant Nuclide:

Sample Area (m):

Scan Area (M2):

Scan Coverage (%):

Zl-, :

Sign P:

Calculated Relative Shift:

Relative Shift Used:

N-Value:

Design N-Value + 20%:

Design Min Samples N:

Grid Spacing L:

F813 0171 1

309.9 D.A.Tallman 43000 3.5 153866 21500 12035 0.05 0.05 Cs-137 6.89 310 100%

1.645 1.645 0.955435 1.7 1.7 14 17 45 2.6 AB -20' corridor column T - east Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class 1 Default = 50%/o DCGL Class 1 Class 1 Uses 3.0 if Relative Shift is >3 NUREG-1575 Table 5-5 Class 1 Class 1 Page 3 of 9 FSS Summary Report F8130171,

Survey Results:

A total of 45 direct measurements were made in F8130171. 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 2460 to 43561 dpm/l100 cm2, based on a surveyor efficiency of 0.5 and no background subtracted. ISOCS scan activity on the walls and ceiling ranged from 982 to 2972 dpm/100cm 2 for Cs-137 with all scans less than MDA for Co-60. 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 F8130171

Table 2. Direct Measurement Results

.Y.

Measurement ID Gross Activity (dpm/100 cm

.4-F8130171-C0001BD F8130171 -CO002BD F8130171 -CO003BD F8130171-CO004BD F8130171-CO005BD F8130171-CO006BD F8130171-CO007BD F8130171-CO0OBBD F8130171 -CO009BD F8130171 -CO01OBD F8130171-CO011BD F8130171-CO012BD F8130171-Co013BD F8130171-CO014BD F8130171-CO015BD F8130171-CO016BD F8130171 -CO01 7BD F8130171-CO018BD F8130171--Co019BD F8130171-CO02OBD F8130171-CO021BD F8130171-CO022BD F8130171-CO023BD F8130171-CO024BD F8130171-CO025BD F8130171 -CO026BD F8130171 -CO027BD F8130171 -CO028BD F8130171 -CO029BD F8130171 -CO03OBD F8130171-CO031BD F8130171-CO032BD F8130171-CO033BD F8130171 -CO034BD FB130171 -CO035BD F8130171-CO036BD F8130171-CO037BD F8130171-CO038BD F8130171-CO039BD F8130171,C0040BD F8130171-CO041BD F8130171-CO042BD F8130171 -CO043BD F8130171 -C0044BD F8130171 -CO045BD Mean:

Median:

Standard Deviation:

Ranqe:

1712 2469 2070 1696 1816 1722 1665 975 1032 1395 1784 1515 1639 1437 1318 1629 1478 1660 1323 1499 1489 1525 1432 1359 1198 1577 1639 1385 1484 1655 1432 1.333 1624 1624 1312 1286 1499 1261 1567 1515 1261 1468 1458 1426 1478 1514 1489 247 975 - 2469 Page 5 of 9 FSS Summary Report F8130171

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

F8130171COOOISM F8130171 C0002SM F8130171 C0003SM F8130171 C0004SM F8130171C0005SM F8130171 C0006SM F8130171 C0007SM F8130171 C0008SM F8130171 C0009SM F8130171CO010SM F8130171CO011SM F8130171 Co012SM F8130171C0013SM F8130171CO014SM F8130171CO015SM F8130171Co016SM F8130171Co017SM F8130171Co018SM F8130171C0019SM F8130171 C0020SM F8130171 C0021 SM F8130171 C0022SM F8130171 C0023SM F8130171C0024SM F8130171 C0025SM F8130171 C0026SM F8130171 C0027SM F8130171 C0028SM F8130171 C0029SM F8130171 C0030SM F8130171CO031SM F8130171 C0032SM F8130171 C0033SM F8130171 C0034SM F8130171 C0035SM F8130171 C0036SM F8130171 C0037SM F8130171 C0038SM F8130171C0039SM F8130171CO040SM F8130171CO041SM F8130171 C0042SM F8130171 C0043SM F8130171 C0044SM F8130171 C0045SM Mean:

Median:

Standard Deviation:

Range:

4.22

-3.53 0.34

-3.53

-0.95

-4.82

-3.53 1.64

-2.24

-3.53 5.51 2.93 0.34 2.93 4.22

-0.95 8.09 18.42 8.09 0.34 9.38 1.64

-3.53

-3.53

-0.95

-0.95 1.64 6.8 2.93 5.51 13.26 31.34

-3.53

-3.53 23.59 2.93 5.51

-2.24 13.26 5.51 11.97 5.51

-2.24

-3.53 1.64 3.57 1.64 7.72

-4.82 to 31.34 Page 6 of 9 FSS Summary Report F8130171

Survey Unit Data Assessment:.

The survey design required 45 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 F8130171

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):

45 Median (dpm!100 cm 2):

1489 Mean (dpm/100 cm 2):

1514 Direct Measurement Standard Deviation 247 (dpm/100 cm 2):

Total Standard Deviation (dpm/100 cm 2):

247 Based on samples and backgrounds.

Maximum (dpm/100 cm 2):

2469 Material Type:

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

45 S+ Value:

45 Critical Value:

28 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 8 of 9 FSS Summary Report F8130171

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. 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. 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 F8130171 meets the release criteria of 10CFR20.1402.

Page 9 of 9 FSS Summary Report

.F8130171 Maps

'June 11, 2008 Survey Unit F8130071

Attachment I Maps June 19, 2008 Survey Unit F8130171

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

Model; Serial No.

(dpm/100 cm')

(dpm/100 cm2 )

550A 990A M2350; 142514 43-98B; 148639 820B 1490B M2350; 175834 43-68B; 148634 433c 1033 C 796 c 3258 M2350; 175834 43-116-iB; 190642 472D 1930D 4 9 1E 739E Tennelec; 0401171 N/A 6 dpm a, 12 dpmJ3 N/A A Penetration - 3" - metal B Penetration - 4" - metal c Surfacescan - concrete D Surface scan - metal E Juncture - concrete Instrument Detector MDC Model; Serial No.

Model; Serial No.

(dpm/100 cm 2 )

989 (Co60)

ISOCS 1983920 1340 (Cs137) 3920_2mconcrete geometry 12.5 M2 FOV Table 2-2. Investigation Criteria and DCGL Parameter Value (dpm/100 cm 2)

Investigation Criteria - Direct 153866 Investigation Criteria - Scan 153866 DCGLw 43000 DCGLEMC 153866 Value (dpm/100 cm 2 )

Instrument Parameter To detect a 1 m hot spot at the EMC Criterion within the detector field of view Investigation Criteria -

63,300 dpm/100 cm2 Cs-137 ISOCS Concrete Scan 1',2 21,275 dpm/100 cm 2 Co-60 3920 2mconcrete geometry 12.5 m2 FOV 2 Investigation Level set to 43,000 dpm/100cm2 Cs-137, ND Co-60 for investigation survey instructions.

Page 2 of 2 Att. 2 Instrumentation F8130171 Investigation June 19, 2008 Survey Unit F8130171 (none required)

Data Assessment June 19, 2008 Survey Unit F8130171

CD ITIl 00 0j F81 30171 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1OOcm 2 Z%

3,000 2,500 2,000 1,500 1,000 1489 500 0

0 20 40 60 80 100 Percentile S

Direct Measurements (dpm/100cm2) -

median -

- -75th Percentile 50th Percentile

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