ML091000373

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Final Status Survey Summary Report for October 1, 2008, Fuel Storage Building, West Exterior Wall, (+) 0 El. to (+) 20 El, Survey Unit F8120121
ML091000373
Person / Time
Site: Rancho Seco
Issue date: 10/01/2008
From:
Sacramento Municipal Utility District (SMUD)
To:
NRC/FSME
Shared Package
ML090830613 List: ... further results
References
DPG 09-097
Download: ML091000373 (32)
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Rancho Seco Final Status Survey Summary Report October 1, 2008 Fuel Storage Building, West Exterior Wall, (+) 0' El. to (+) 20' El.

Survey Unit F8120121 Prepared By:

r._.xt-A-Date:

Ii/Z FSS Engineer Reviewed By:

It*AJ

-3IDate:..

.L(c[

Lead FSS Engineer Approved By:

.I Date:

Dismantlement S eprinten dent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8120121, Fuel Storage Building, West Exterior Wall, (+) 0' El. to (+) 20' El.

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 cm2 and a maximum value of 200,000,000 dpm/100 cm 2. 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 cm2.

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 Class 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 I 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 122.5 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 F8120121

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

F812 Survey Unit:

Class:

SU Area (m2):

Evaluator:

DCGL (dpm/100 cmr):

Area Factor:

Design DCGLemc (dpm/100 cm 2):

LBGR (dpm/100 cm2):

Design Sigma (dpm/100 cm2):

Type I Error:

Type II Error:

Predominant Nuclide:

Sample Area (m2):

Scan Area (M2):

Scan Coverage (%):

ZI-P :

Sign P:

Calculated Relative Shift:

Relative Shift Used:

N-Value:

Design N-Value + 20%:

Design Min Samples N:

Grid Spacing L:

0121 1

122.5 D. Anderson 43,000 3.6 154,800 40,759 747 0.05 0.05 Cs-137 6.8 122.5 100%

1.645 1.645 0.99865 3

3 11 14 18 2.6 Fuel Storage Building, West Exterior Wall, (+) 0' El. to

(+) 20' El.

Structure Surface LTP Table 5-4 Gross Activity DCGL Class I Class 1 Adjusted Class 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 F8120121

Survey Results:

A total of 18 direct measurements were made in F8120121. 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 < 905 dpm/100 cm 2 Co-60 and <1,240 dpm/100 cm 2 to 40,994 dpm/100 cm2 Cs-137. Beta scan activity ranged from 2,581 to 23,504 dpm/100 cm 2, based on a surveyor efficiency of 0.5 and no background subtracted. Soil samples collected from the trench adjacent to the structure identified the highest soil activity as 0.71 pCi/g Cs-137. Co-60 was not identified in soil above the MDA. 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 F8120121 -C0001 BD F8120121-CO002BD F8120121 -CO003BD F8120121 -X0004BD F8120121 -CO005BD F8120121 -XO006BD F8120121-CO007BD F8120121 -XO008BD F8120121-CO009BD F8120121 -XO010BD F8120121-CO011BD F8120121-XO012BD F8120121-CO013BD F8120121-XO014BD F8120121-Co015BD F8120121-XO016BD F8120121-CO017BD F8120121-XO018BD Mean:

Median:

Standard Deviation:

Range:

1,473 2,106 1,515 3,020 1,592 2,833 1,546 2,877 1,406 2,789 1,411 2,866 1,442 2,921 1,478 4,012 1,530 2,800 2,201 1,849 808 1,406 - 4,012 Page 4 of 8 FSS Summary Report F8120121

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

F8120121COOOISM F8120121 C0002SM F8120121C0003SM F8120121X0004SM F8120121 C0005SM F8120121X0006SM F81 20121 C0007SM F8120121XO008SM F8120121 C0009SM F8120121X0010SM F8120121CO01ISM F8120121X0012SM F8120121Co013SM F8120121XO014SM F8120121Co015SM F8120121X0016SM F8120121 C0017SM F8120121X0018SM Mean:

Median:

Standard Deviation:

Ranqe:

-4.82

-4.82

-4.82

-3.53

-3.53

-0.95

-0.95

-3.53

-4.82

-0.95

-4.82 2.93

-3.53

-2.24 0.34 2.93

-4.82

-4.82

-2.6

-3.53 2.61

-4.82 to 2.93 Page 5 of 8 FSS Summary Report F8120121

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 greater than the design standard deviation. Since both values of sigma resulted in a relative shift greater than three (3), no additional samples were required.

Page 6 of 8 FSS Summary Report F8120121

Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm 2):

Ambient Background Used (dpm/100 cm 2):

Actual Direct Measurements (N):

Median (dpm/100 cm 2):

Mean (dpm/100 cm 2):

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

Total Standard Deviation (dpm/100 cm 2):

Maximum (dpm/100 cm 2):

Material Type:

Sign Test Final N Value:

S+ Value:

Critical Value:

Sufficient Samples Collected:

Maximum Value < DCGL:

Median Value < DCGL:

Mean Value < DCGL:

Maximum Value < DCGLemc:

Total Standard Deviation <= Sigma:

Pass the Sign Test?

Reject the Null Hypothesis?

Does the Survey Unit Pass All Criteria?

N/A N/A 18 1,849 2,201 808 808 4,012 N/A

  • 18 18 12 Yes Yes Yes Yes Yes

.Investigate Yes Yes Investigate Average Ambient BKG = 0 Based on samples and backgrounds.

-Background Subtract Not Applied Class 1 All samples < DCGL. SU passes.

All samples < DCGL. SU passes.

Page 7 of 8 FSS Summary Report F81'20121

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 greater than the characterization data used for survey design. However, no additional samples were required. 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 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 F8120121.meets the release criteria of IOCFR20.1402.

Page 8 of 8 FSS Summary Report F8120121 Maps October 1, 2008 Survey Unit F8120121

00 Ci)

O° Map F8120121-1, Fuel Storage Building Location at Rancho Seco site

L-~

16 1ft 61.5 ft 0

2 4

6 8

Distance in Foee Map F8120121-2, Fuel Storage Building West Exterior Wall, (-3)' El. to 20' El. (Class 1)

Area Estimate: 122.5 sq. meters Page 3 of 16 Att. I Maps F8120121

69'4" El I.

i I

]I I

I iI I

II 40' El.

(OPEN)

Random Start Location 0.2 m from south corner 3.6 m above grade (0' El

",Iii li' 1

+/-,-U-4-, -

S g-4-+

L j i-

+

44

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1 t.

4 F_

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 10 125 N

0 1

2 3

4 Distance in Meters Map F8120121-3, Fuel Storage Building West Exterior Wall, (-) 3' El. to 20' El. (Class 1)

Random Start Location Page 4 of 16 Att. 1 Maps F8120121

N-o 1

2 3

4 Distance in Meters Map F8120121-4, Fuel Storage Building West Exterior Wall, (-) 3' El. to 20' El. (Class 1)

Beta Direct Measurements F8120121 C0001BD to F8120121 C0018BD 2.55 sq. meter grid spacing Page 5 of 16 Att. 1 Maps F8120121

I-TI 40' El.

20' El.

O'El.

Map F8120121-5, Fuel Storage Building West Exterior Wall, (-) 3' El. to 20' El. (Class 1)

N Beta Scan Measurements o0 05F8120121CO001BS to F8120121CO019BS, Dislam, in Metem F8120121C0040BS to F8120121 C0041BS, F8120121CO082BS to F8120121CO083BS and F8120121CO124BS to F8120121CO125BS

CD 40' El.

20' El.

0 El.

ccJ N

0 0 10 15 2.0 Distance in Meters Map F8120121-6, Fuel Storage Building West Exterior Wall, 0' El. to 20' El. (Class 1)

Juncture Scan Measurement F8120121C0001JS

CD 00 CN 00 40' El.

20' El.

0' El.

N o1

.0

- Distane i. Metem Map F8120121-7, Fuel Storage Building West Exterior Wall, 0' El. to 20' El. (Class 1)

Penetration Scan Measurements F8120121POOO1BS to F8120121P0004BS

0 cd0 T1-1 00 40' El.

Distance in meters E

(0 from SW corner IP E

(0a)

E L0 Nl (0

E (0

E 0O0 E

C')

E N

E 0

0.5 1.0 1.5 2.0 Distance in Meters Map F8120121-8, Fuel Storage Building West Exterior Wall, 0' El. to 20' El. (Class 1)

ISOCS Gamma Scan Measurements F8120121 CO001GS to F8120121 C0024GS 3.14 sq. meter field of view

c"Q G

o 40' El.

'-)

(OPEN)

E E

E E

E E

E 0)N-0)

U)

I-It 00

)?

Height in meters rom grade S-----2-0 2-1~58GS 57GS 56GS5G 4S5G 2s56-(OEN 43GS 44GS 45GS 4

7G 4GS 48GS 49GS 5G 29G 3G

.59I m 25G IS 26GS 27GS 28GS 29S30GS 31 GS 32GS3 El Distance in meters E

-4 E

C C

0) from SW cornero CN q

o, (N

0 4

D0 00 o

Map F8120121-9, Fuel Storage Building West Exterior Wall, 0" El. to 20' El. (Class 1)

N ISOCS Gamma Scan Measurements 0 0.5 1.0 1.5 2.0 F8120121C0025GS to F8120121 C0053GS Distance in Meters 3.14 so. meter field of view F8120121C0052GS to F8120121C0058GS 6.2 sq. meter field of view

cic~

0 ON 40' El.

It 00 N

0 0.5 1.0 1.5 2.0 Distance in Meters Map F8120121-10, Fuel Storage Building West Exterior Wall, 0' El. to 20' El. (Class 1)

ISOCS Gamma Scan Measurements F8120121C0001GS to F8120121C0058GS

P 67 tt41 004 Map F8120121-11, Fuel Storage Building tWest Exterior Wall, (-) 3' El. to 20' El. (Class 1)

Nal Gamma Scan Measurements F8120121S0001GS to F8120121S0010GS

I r

rEl 00 Map F8120121-12, Fuel Storage Building West Exterior Wall, (-) 3' El. to 20' El. (Class 1)

Soil Sample Locations F8120121S0001SS to F8120121S0010SS

CDo 0

Soil adjacent to west SFB exterior wall I,ý DDTZ-

"F-0D0DD W)

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P 90 3

3 M

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0

-4 CO WD 01 9

3 3

3 3

0 11 0 0 0 0 0

11

[] []

MI

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00 ED Map F8120121-13, Turbine Building (+) 0' El.

Soil area adjacent to West Spent Fuel Bldg Exterior Wall ISOCS gamma scan measurements F8120121S0021GS to F8120121S0031GS 12.57 sq. meter field of view N

0 2

4 6

8 Distance in Meters

CD A

>~

00W Map F8120121-14, Fuel Storage Building

~West Exterior Wall, (-) 3' El. to 20' El. (Class 1)

Nal Background Locations F8120121S0001GS to F8120121S0020GS I-

ON Fil LZI ILZF-

[1DDF 0

0o 9

0)

"4 00 9

9 9

0 0 0 0 n]

LFl rio

~T1 00 k) 0 DI Map F8120121-15, Turbine Building (+) 0' El.

Soil area adjacent to west Spent Fuel Bldg exterior wall ISOCS gamma scan measurements F8120121S0032GS to F8120121S0041GS 7.1 sq. meter field of view N

I 0

2 4

6 8

Distance in Meters Instrumentation October 1, 2008 Survey Unit F8120121

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; 142514 43-98B; 148639 1,400 2,520 M2350; 193700 43-68B; 190294' 433 1,033 M2350; 193700 43-68B; 1902942 909 2,169 M2350; 142509 43-68B; 160699' 433 1,033 M2350; 142509 43-68B; 1606992 909 2,169 M2350; 193700 43-116-1B; 216072 491 739 Tennelec; 0401171 N/A 5.88 dpm a, N/A

____11.71 dpmr

'Concrete surfaces 2Concrete surfaces with 1 layer of paint Instrument Detector Detector Model No.

Serial No.

Concrete - 1,220 dpm/100 cm 2 Cs-137, ISOCS N/A 1983920 Concrete - 905 dpm/100 cm 2 Co-60 Concrete - 1,240 dpm/100 cm 2 Cs-137, ISOCS N/A 2983947 Concrete - 856 dpm/100 cm 2 Co-60 Instrument Detector MDC Static MDC Scan Model; Serial No.

Model; Serial No.

(pCi/g)

(pCilg)

M2350; 193700 44-10; 256101 N/A 5.2 M2350; 193715 44-10; 171374 N/A 5.2 Instrument Detector Detector Model No.

Serial No.

Soil -0.34 pCi/g Cs-137, ISOCS N/A 1983920 Soil -0.3 pCi/g Co-GO Soil - 0.23 pCi/g Co-60 ISOCS N/A 2983947 Soil - 0.23 pCi/g Cs-137, 1

1 Soil - 0.26 pCi/g Co-60 Soil - 0.06 pCi/g Cs-137, Soil - 0.07 pCi/g Co-60 Page 2 of 3 Att. 2 Instrumentation F8120121

Table 2-2. Investigation Criteria and DCGL Value Parameter (dpmlO CM)

Investigation Criteria - Direct 154,800 Investigation Criteria - Scan

-154,800 Investigation Criteria-Scan 186,000 Cs-137 (ISOCS average activity - 3.14 64,000 Co-60 sq. meter field of view)

Investigation Criteria - Scan 63,000 Cs-137 (ISOCS average activity - 6.2 21,000 Co-60 sq. meter field of view)

DCGLw 43,000 DCGLEMC 154,800 J.

Page 3 of 3 Att. 2 Instrumentation F8120121 Investigation October 1, 2008 Survey Unit F8120121 (none required)

Data Assessment October 1, 2008 Survey Unit F8120121

CD Ct)

CD 00 F8120121 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm2 4-4,500 4,000 3,500 3,000 2,500 2,000 1,500 1,000 500 0

1849 0

20 40 60 80 100 P-'ercentile SDirect Measurements (dpm/1 cm2)

-median 75th Percentile 50th Percentile

0" 2.,

F8120121 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpml00cm=1 5000 4624 4000 E

0 0

0

,-.+

aE 2000

.2201 0

0 0

0 0

0 ZL1 0 0 0 0

00 0

0000 0

-00 0

000000 CD) r 0000 N

O N

0 t

ON 00 000 00*0 0

0 r-T-

rv V-r-

VS r

r" Measurement Locations 00 G

c..

[,,.

0 (ti F81 20121 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm2 9

8 r-0

ý7 6

5 4

3 2

1 0

Cl Cr)

Cl 00 tQ Bins - Upper End Value (dpm/1 00cm2)

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