ML091000388

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Final Status Survey Summary Report for July 22, 2008 Fuel Storage Bldg (+) 40 El., Auxiliary Bldg End, Lower Walls Survey Unit F8121003
ML091000388
Person / Time
Site: Rancho Seco
Issue date: 07/22/2008
From: Donna Anderson
Sacramento Municipal Utility District (SMUD)
To:
NRC/FSME
Shared Package
ML090830613 List: ... further results
References
DPG 09-097
Download: ML091000388 (27)
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Rancho Seco Final Status Survey Summary Report July 22, 2008 Fuel Storage Bldg (+) 40' El., Auxiliary Bldg end, Lower Walls Survey Unit F8121003 Prepared By:

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Date:.

7I2/*2-1 /A FSS Engineer Reviewed By:

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?4 Lead FSS Engineer Approved By:

Date:______

Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8121003, Fuel Storage Bldg (+) 40' El., Auxiliary Bldg end, Lower Walls Survey Unit

Description:

Operating History: The reinforced concrete structure contained the spent fuel pool and supporting systems. The building contained three main elevations including the pool.

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. Three documented instances of contamination through the common fuel building/turbine building wall were noted.

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 pool elevation showed a mean gross activity level of 16,900,000 dpm/100 cm 2 and a maximum value of 200,000,000 dpm/100 cm2. Direct measurements on the +40' elevation showed a mean gross activity level of 5,942 dpm/100 cm2 and a maximum value of 19,357 dpm/100 cm 2.

Direct measurements on the building exterior showed a mean gross activity level of 1,408 dpm/100 cm 2 and a maximum value of 21,600 dpm/100 cm 2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the interior of the spent fuel building was determined to be a Clafs 1,2 area and the exterior was a Class 2, 3.

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 115.8 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 F8121003

/

Table 1. Survey Unit Design Parameters Survey Design

Value, Comment Parameter Survey Area:

F812 Survey Unit:

Class:

SU Area (m2):

Evaluator:

DCGL (dpm/100 cm2):

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 (m2):

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:

1003 1

115.8 D. Anderson 43,000 3.4 146,200 29,107 4,631 0.05 0.05 Cs-137 2.6 115.8 100%

1.645 1.645 0.99865 3

3 11 14 17 2.6 Fuel Storage Bldg (+) 40' El., Auxiliary Bldg end, Lower Walls Structure Surface LTP Table 5-4 Gross Activity DCGL Class I Class 1 Adjusted Class 1 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 F8121003

Survey Results:

A total of 26 direct measurements were made in F8121003. 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. The gamma activity ranged from < 943 dpm/100 cm2 Co-60 and < 1,3.10 dpm/100 cm 2 to 917 dpm/100 cm2 Cs-137. Beta scan activity ranged from 5,510 to 10,804 dpmr/100 cm2, 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 Activity (dpm/100 cm F8121003-CO001BD F8121003-CO002BD F8121003-CO003BD F8121003-C0004BD F8121003-CO005BD F8121003-C0006BD F8121003-CO007BD F8121003-CO008BD F8121003-C0009BD F8121003-CO01 OBD F8121003-COOIIBD F8121003-Co012BD F8121003-CO01 3BD F8121003-CO014BD F8121003-Co01 5BD F8121003-Co016BD F8121003-CO017BD F8121003-Co018BD F8121003-Co019BD F8121003-CO02OBD F8121003-C0021 BD F8121003-CO022BD F8121003-CO023BD F8121003-CO024BD F8121003-CO025BD F8121003-CO026BD Mean:

Median:

Standard Deviation:

Range:

3,329 3,417 4,321 3,869 3,693 3,274 4,387 3,913 3,704 3,505 3,792 4,078 4,189 3,858 3,627 3,957 3,472 3,549 3,153 3,869 3,417 3,814 3,902 4,023 3,770 2,756 3,717 3,781 368 2,756 - 4,387 Page 4 of 8 FSS Summary Report F8121003

Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm2)

F8121,003C0001 SM F8121003C0002SM F8121003CO003SM F8121003C0004SM F8121003C0005SM F8121003CO006SM F8121003CO007SM F8121003CO008SM F8121003C0009SM F8121003CO010SM F8121003C001 1 SM F8121003C0012SM F8121003C0013SM F8121003CO014SM F8121003C0015SM F8121003C0016SM F8121003CO017SM F8121003C0018SM F8121003C0019SM F8121003C0020SM F8121003CO02ISM F8121003C0022SM F8121003C0023SM F8121003C0024SM F8121003C0025SM F8121003C0026SM Mean:

Median:

Standard Deviation:

Range:

0.34 6.8 0.34 0.34 2.93

-4.82

-3.53

-0.95

-2.24

-2.24 0.34

-0.95 1.64

-2.24 0.34

-3.53

-2.24

-4.82

-4.82

-3.53

-2.24 6.8 2.93 1.64 1.64

-0.95

-0.5

-0.95 3.14

-4.82 to 6.8 Page 5 of 8 FSS Summary Report F8121003

Survey Unit Data Assessment:

The survey design required 26 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 F8121003

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):

26 Median (dpm/100 cm 2):

3,781 Mean (dpm/100 cm 2):

3,717 Direct Measurement Standard Deviation 368 (dpm/100 cm 2):

Total Standard Deviation (dpm/100 cm 2):

368 Based on samples and backgrounds.

Maximum (dpm/O00 cm 2):

4,387 Material Type:

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

26 S+ Value:

26 Critical Value:

17 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

.F8121003

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 43,000 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 F8121003 meets the release criteria of 10CFR20.1402.

Page8 of8 FSS Summary Report F8121003 Maps July 22, 2008 Survey Unit F8121003

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00 33.75 ft. - 10.29 m N

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1 2

3 4

Distance in Motors Map F8121003-1, Fuel Storage Building +40' El. (Aux Bldg end)

East Wall (Lower 3 meters) Area Estimate: 36.7 sq. meters

1E 43 ft. - 13.11 m South Wall 0

1 2

3 4

DistanOc in Meters Map F8121003-2, Fuel Storage Building +40' El. (Aux Bldg end)

South Wall (Lower 3 meters) Area Estimate: 43.2 sq. meters Page 3 of 12 Att. 1 Maps F8121003

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0 33.75 ft. - 10.29 m It.,

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1 2

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Dostanco in Meters Map F8121003-3, Fuel Storage Building +40' El. (Aux Bldg end)

West Wall (Lower 3 meters) Area Estimate: 35.8 sq. meters

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5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 Map F8121002-4, Fuel Storage Building +40' El. (Aux Bldg end)

Lower Walls (Lower 3 meters) Random Start Location F.,

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4 Distance in Meters Page 5 of 12 Att. I Maps F8121003

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East Wall (Lower 3 meters) Beta Direct Measurements F8121003CO001BD to F8121003C0008BD 2.60 sq. meter grid

l-Height in meters 3.0 m 0.40 m 0

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Distance in Meters Map F8121003-6, Fuel Storage Building +40' El. (Aux Bldg end)

South Wall (Lower 3 meters) Beta Direct Measurements F8121003C0009BD to F8121003C0018BD 2.60 sq. meter grid Page 7 of 12 Att. 1 Maps F8121003

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4 Distance in Motors Map F8121003-7, Fuel Storage Building +40' El. (Aux Bldg end)

West Wall (Lower 3 meters) Beta Direct Measurements F8121003C0019BD to F8121003C0026BD 2.60 sq. meter grid

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4 Distance in Meters Map F8121003-8, Fuel Storage Building +40' El. (Aux Bldg end)

East Wall (Lower 3 meters) Gamma Scan Measurements F8121003C0001GS to F8121003C0003GS 28 sq. meter field of view

Height in

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4 Distance in Meters Map F8121003-9, Fuel Storage Building +40' El. (Aux Bldg end)

South Wall (Lower 3 meters) Gamma Scan Measurements F8121003C0004GS to F8121003C0006GS 28 sq. meter field of view Page 10 of 12 Att. I Maps F8121003

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Distance in Meters Map F8121003-10, Fuel Storage Building +40' El. (Aux Bldg end)

West Wall (Lower 3 meters) Gamma Scan Measurements F8121003C0007GS to F8121003C0009GS 28 sq. meter field of view

Map F8121003-11, Fuel Storage Building +40' El. -Aux Bldg end Lower Wall (10 ft) Penetration Scan Measurements F8121003P0001BS to F8121003P0005BS Page 12 of 12 Att. 1 Maps F8121003 Instrumentation July 22, 2008 Survey Unit F8121003

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; 189089 43-68B; 161406 433 1,033 M2350; 175834 43-116-1B; 190642 796 3,258 Tennelec; 0401171 N/A 5.88 dpm a, N/A 11.71ldpmf_

IDetector Detector MDC ivioael No.

Serial Nio.

Concrete - 1,310 dpm/100 cm2 Cs-137, ISOCS N/A 1983920 Concrete-943 dpm/100 cm 2 Co-60 Table 2-2. Investigation Criteria and DCGL Value Param eter V l eC 2

(dpm/100 cm 2)

Investigation Criteria - Direct 146,200 Investigation Criteria - Scan 146,200 Investigation Criteria - Scan (ISOCS average activity - 28 sq.

23,900 meter field of view)

DCGLw 43,000 DCGLEMC 146,200 Page 2 of 2 Att. 2 Instrumentation F8121003 Investigation July 22, 2008 Survey Unit F8121003 (none required)

Data Assessment July 22, 2008 Survey Unit F8121003

Cn 00 F8121003 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm2 I

7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

3781 0

20 40 60 Percentile 80 100 I*

Direct Measurements (dpm/100cm2)

-median

- 75th Percentile

- 50th Percentile I

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F8121003 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpml00ocm=

Coa Cna c-f 6000 OR" 5000 E

ug 4000 E.

E. 3000 2000 C1000 0

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Measurement Locations oY Gros civity Average-

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F81 21003 Gross Activity, Frequency Plot DCGL = 43000 dpm/1 00cm2 0

00 I'J C) 0~

4-0l 8

7 6

5 4

3 2

1 0

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00 LO c'J Bins - Upper End Value (dpm/1 00cm2)

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