ML090890537

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Final Status Survey Summary Report 09/08/08, Turbine Building West H.P.Pit (-) 10' El., Survey Unit F8260008
ML090890537
Person / Time
Site: Rancho Seco
Issue date: 09/08/2008
From:
Sacramento Municipal Utility District (SMUD)
To:
NRC/FSME
Shared Package
ML090830613 List: ... further results
References
DPG 09-097, F8260008
Download: ML090890537 (26)
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Text

Rancho Seco Final Status Survey Summary Report September 8, 2008 Turbine Building West H. P. Pit (-) 10' El.

Survey Unit F8260008 Prepared By: t . d.o _. Date: q/? /?M'-

FSS Engineer Reviewed By: \ 4" Date: ,- L Lead FSS Engineer Approved By: Date:_______

Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8260008, Turbine Building West H. P. Pit (-) 10' El.

Survey Unit

Description:

Operating History: The reinforced concrete and steel structure contained the turbine-generator and supporting systems. The building contained five 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. Direct measurements in the condenser pit elevation showed a mean gross activity level of 3,077 dpm/100 cm2 and a maximum value of 24,900 dpm/100 cm 2 . Direct measurements on the grade elevation showed a mean gross activity level of 2,035 dpm/100 cm 2 and a maximum value of 6,980 dpm/100 cm 2. Direct measurements on the mezzanine elevation showed a mean gross activity level of 1,566 dpm/100 cm 2 and a maximum value of 2,626 dpm/100 cm 2 . Direct measurements on the +40' elevation showed a mean gross activity level of 2,843 dpm/ 100 cm 2 and a maximum value of 3,615 dpm! 100 cm 2 . Direct measurements on the building exterior showed a mean gross activity level of 1,984 dpm/100 cm 2 and a maximum value of 10,312 dpm/100 cm 2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the interior of the turbine building was determined to be Class 1, 2, & 3 areas and the exterior was a Class 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 2

locations were determined using a random-start, fixed grid pattern and 262.5 m were scanned for approximately 76% 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 F8260008

Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F826 Turbine Building West H.

P. Pit (-) 10' El.

Survey Unit: 0008 Structure Surface Class: 2 LTP Table 5-4 SU Area (m2): 346 Evaluator: D. Anderson DCGL (dpm/100 cm 2): 43,000 Gross Activity DCGL Area Factor: N/A Class 2 Design DCGLemc N/A Class 2 (dpm/r100 cm2 ):

LBGR (dpm/100 cm 2 ): 25,030 Adjusted Design Sigma (dpm/100 cm 2 ): 5,990 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): 24.71 Class 2 Scan Area (M2): 262.5 Scan Coverage (%): 76% Class 2 1.645 1.645 Sign P: 0.99865 Calculated Relative Shift: 3 Relative Shift Used: 3 Uses 3.0 if Relative Shift is

>3 N-Value: 11 Design N-Value + 20%: 14 NUREG-1575 Table 5-5 Design Min Samples N: 14 Class 2 Grid Spacina L: 4.9 Class 2 Page 3 of 8 FSS Summary Report F8260008

Survey Results:

A total of 17 direct measurements were made in F8260008. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. One of the scan measurements indicated an area of elevated activity. Beta scan activity ranged from 3,631 to 46,275 dpm/100 cm2 , based on a surveyor efficiency of 0.5 and no background subtracted. A direct measurement taken at the location of elevated activity was evaluated as 37,758 dpm/100 cm 2 , as shown inTable 3-1 of Attachment 3. The second highest beta scan measurement was determined to be 19,961 dpm/l00 cm2. 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 F8260008-CO001BD 2,827 F8260008-CO002BD 2,173 F8260008-CO003BD 2,173 F8260008-CO004BD 2,298 F8260008-CO005BD 2,661 F8260008-CO006BD 2,661 F8260008-CO007BD 2,210 F8260008-CO008BD 2,438 F8260008-CO009BD 2,760 F8260008-CO01OBD 2,246 F8260008-Co01 1 BD 1,675 F8260008-CO012BD 1,816 F8260008-CO01 3BD 1,888 F8260008-CO014BD 1,826 F8260008-COOI 5BD 1,774 F8260008-CO01 6BD 1,774 F8260008-CO01 7BD 1,764 Mean: 2,174 Median: 2,173 Standard Deviation: 388 Range: 1,675 - 2,827 Page 4 of 8 FSS Summary Report F8260008

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

F8260008C0001SM 1.64 F8260008C0002SM -4.82 F8260008C0003SM 1.64 F8260008C0004SM 4.22 F8260008C0005SM -0.95 F8260008C0006SM -0.95 F8260008C0007SM -4.82 F8260008C0008SM -3.53 F8260008C0009SM -0.95 F8260008C0010SM -2.24 F8260008C001 1SM 0.34 F8260008C0012SM -2.24 F8260008C0013SM -3.53 F8260008C0014SM -4.82 F8260008C001 5SM -2.24 F8260008C001 6SM -4.82 F8260008C0017SM 1.64 Mean: -1.55 Median: -2.24 Standard Deviation: 2.74 Range: -4.82 to 4.22 Page 5 of 8 FSS Summary Report F8260008

Survey Unit Data Assessment:

The survey design required 17 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 F8260008

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): 17 Median (dprn 100 cm 2): 2,173 Mean (dpm/100 cm 2): 2,174 Direct Measurement Standard Deviation 388 (dpm/1 00 cm 2 ):

2 Total Standard Deviation (dprm/100 cm ): 388 Based on samples and backgrounds.

2 Maximum (dpm/100 cm ): 2,827 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 17 S+ Value: 17 Critical Value: 12 Sufficient Samples Collected: Yes Maximum Value < DCGL: Yes Median Value < DCGL: Yes Mean Value < DCGL: Yes Maximum Value < DCGLemc: N/A Class 2 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 F8260008

Survey Unit Investigations and Results:

One investigation (scan grid 102) was required for the scan measurements and the results are reported in Attachment 3.

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 2 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. One potential area of elevated activity was detected and evaluated as shown in Attachment 3.

==

Conclusion:==

The FSS of this survey unit was properly designed as a Class 2 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. One investigation was 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 F8260008 meets the release criteria of 10CFR20.1402.

Page 8 of 8 FSS Summary Report F8260008

Attachment 1 Maps September 8, 2008 Survey Unit F8260008

0 S N Location of Turbine Building inside Industrial Area ZI

..5...ft...

87.08 ft.

0 Interior Wall Height: 10 ft Interior Wall Height: 10 ft- 0 5.7. ft. . s 0 ........ :..!2._4. ft..

wz_ ........

iLr) 0 0 Ii 0

El Interior Wal! Height: 9 ft

..[ 6.9.90.2 ft.

-I'l 00 1 ft 00 Map F8260008-1, Turbine Building 0 1 2 3 Distance in Meters H. P. Pit (-) 10' El.

Area Estimate: 345.4 sq. meters

2 3 4 5 6 7 8 9 10 11 12 13 (D

0o mT U

00 00 Map F8260008-2, Turbine Building (-) 15' 6" El. to (+) 0' El.

N Location of H. P. Pit (-) 10' El.

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"II 00 C) 00 Map F8260008-3, Turbine Building 0 1 2 Distance in Meters 3 H. P. Pit (-) 10' El.

Wall Desiqnations

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Distance in Meters Walls

4 . -f 1 Map!F8260008-5, Turbine Building H PPit-(:)-1O'El 7 CD4 T_ I R-----Randoml-Start Location-C0 S1 !2 3 EastljWali--l-- -outh S Wyall44-l -JWestWalI1{ - - {'{-t -fSqutHiw t-,-F -!-: 4-l ,! ristac n ! elas 4 , 1tj--j L F

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Map F8260008-6, Turbine Building 00 H. P. Pit-(-) 10' El.

Beta Direct Measurements 0 1 2 3 Distance in Meters F8260008C0001BD to F8260008C0010BD 4.97 s-n meter arid snacina

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00 IIB _ 1.8* m 0.44 m -* "__

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East VVaII I SouthI YVVaI I Ael* t. Viial, I OuUtI a~t 4-00 0o Distance E E E E in meters E

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North Wall 1 WNest Wall I' North Wall 2 'East Wall 2' 00 Map F8260008-7, Turbine Building N H. P. Pit (-) 10' El.

Beta Direct Measurements 0 1 2 F8260008C0011BD to F8260008C0017BD Distance in Meters 4.97 sq. meter gridspacing

Map F8260008-8, Turbine Building H. P. Pit (-) 10' El.

Beta Scan Measurements r-Q F8260001 C0001 BS to F8260001 C0221 BS Total Scan Area: 210 sq. meters 0

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I 21BS220BS IBS I 2BS 3BS 4BS 5BS I 6BS I 7BS 8BS i 9BS 1OBS 11BS 12BS 13BS 14BS I15BS 16BS 17BS 18BS 19BS 20BS 21BS 22BSj23BS 124S 25BS BS r 54BS 53BS S 5 0BS 4 8BS 47BS 464S 45BS 4S 4B!3S 4 2 fIS38136BS 40BS 39BS 3843ES I 3B 34S33BS132BS 34BS 3 S 3 3B 30BS 2B 29BS co 55BS 56BS 57BS 58BS 59BS 60BS 616BS 62BS 63BSj64BS 65BS 66BS 67BBS 68BS 69BS 7_0BS 71BS 7I2BS 73BS 74BS 75BS 76BS 77BS 78BS 79BSI 80BS IO8BS107BS1 j~BS1105BS 1041S 1,03BSI'102BS!11'01B8S~ o 99B85 9S: 97BSJB 195BSIJýb4BS 9'3BJ98F 1fOB8BS8SJ7 1,

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cJ516SI 50BS 149BS1148BS 4BS146BSt145B 136ES A15BS 134BS 133BS 132BS 131 BE 4BSl, 3BS 142BSI14,IBS 114OS13BE3 E 154BS'155BS 156BS 15703158S159BS 60BI6iBS1621 163BS 164S165BS166BS167BS168BS169BS170BS171BS172BS 173BSI174BE T)*$194 9 38S 192BS 91BS 19OBS 189BS 88BS 187BS 186BS 185BS1IBBS 183BS 182BS 81BS 180BS 179B*I178BS 177BS 176BS 175BE 198 B S200BS 201'BS02BS 0BS204B 205BS-206BS 207BS '08BS 211BS22 1483B 215BS216B S 217BS 218BS 20 r99BSI29BB 213BSB¶5B

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0 1 2 3 Distancesi Meters

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222B ý.,12.5BS'1'26B1227S,128B.229S 20BS23:B [20*B 1

22523S22BS 2B228 3S23B 232BSt233BS1234BS 21'5BS 236BS 237BS 238BS 23913S,4B East Wall 1 South Wall 1 West Wall 1 South Wall 2 T.. .... .......- 248.249BS.25OBS251BS.252B..5'3.B.S254 BS. 2 6 BS. 7 BS.258S.259S1260B

. 261BS 24B24B24BI24S25S6B Ii 1 78 I I I I- __I West Wall 2 fI,,

00 O0 Map F8260008-9, Turbine Building 00 H. P. Pit (-) 10' El.

N It 4 Beta Scan Measurements F8260001C0222BS to F8260001C0274BS 0 1 2 3 Total Scan Area: 52.5 sq. meters Distance in Meters

Attachment 2 Instrumentation September 8, 2008 Survey Unit F8260008

Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No. Model; Serial No. (dpm/100 cm2 ) (dpm/100 cm2 )

M2350; 193700 43-68B; 190294 433 1,033 M2350; 193700 43-68B; 160691 433 1,033 M2350; 193715 43-116-1B; 256007 796 3,258 Tennelec;0401171NS017N/A 11.71 dpma,3 5.88 dpm N/A Table 2-2. Investigation Criteria and DCGL Value ParameterVau P(dpm/100 cm 2 )

Investigation Criteria - Direct 43,000 Investigation Criteria - Scan 43,000 DCGLw 43,000 DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8260008

Attachment 3 Investigation September 8, 2008 Survey Unit F8260008

Table 3-1 Survey Unit Investigation Investigation Initial Value Investigation Elevated Area Investigation DCGLemc Grid Level (cpm) (cpm) Result Area (m2) Factor DCGLemc Result Unity (cpm) Ae (dpm/lOOcm2) Fraction 102 5,840 6,308 7,269 0.093 N/A 43,000 37,706 0.0 DCGL SU Mean =

Survey Unit Remainder 43,000 2,174 0.051 EMC Unity Sum 0.051 Page 2 of 2 Att. 3 Investigation F8260008

Attachment 4 Data Assessment September 8, 2008 Survey Unit F8260008

I F8260008 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/100cm2 3,500 3,000

-D U) 2,500 2173 2,000 00 I:

4-1,500

.5

.5 1,000 500 00 0

0 20 40 60 80 100 Percentile

  • Direct Measurements (dpm/1 00cm2) median - - _75th Percentile - -- - 50th Percentile

-e a

U.)

0 F8260008 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmiO00cm1 4000

,3500 3337 E

o 3000 0

0 0 0

> r 2500 0-2174 2000 00 0 0 0 1600 -~~~~~~~~~ -0 ln a

lEn 1000- 1 1012 500 0 $

r N R to 0 1%. 00 0) Oa N 0(V) t W ON 00000 a0 0 Or-re r V e-0 00 00 0 0 0 0 000 0a 0 0 0 0 0U C O a U 0U 0O 0U U 0U a U 000 0U U O 0U 0U 0a 0U 0U U

Measurement Locations 00 k) o GrossAdClvŽy - .Average_= - "+3StDev" -_-_"-3StDev' 0

0 00

F8260008 Gross Activity Frequency Plot 2

DCGL = 43000 dprn/1 OOCM 4-3 0L C

-0 2

0 00 4-a) 1 -

0

0) LO I,-

N-(D 0) N- L()

C" Bins - Upper End Value (dpm/1 00cm2)

...........

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