ML082620123

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Fuel Storage Building Cask Catcher Pad, Survey Unit F8120111
ML082620123
Person / Time
Site: Rancho Seco
Issue date: 04/16/2008
From: Donna Anderson
Sacramento Municipal Utility District (SMUD)
To:
NRC/FSME
References
MPC&D 08-064
Download: ML082620123 (27)
v • d • e


Text

Rancho Seco Final Status Survey Summary Report April 16, 2008 Fuel Storage Building Cask Catcher Pad Survey Unit F8120111 Prepared By: ________ ______ Date: 4_1______

Reviewed By: Date:

Approved.By:{ Date: 7 * -

Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8120111, Fuel Storage Building Cask Catcher Pad 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/l100 cm 2 and a maximum value of 200,000,000 dpm!1 00 cm2 . Direct measurements on the +40' elevation showed a mean gross activity level of 5,942 dpm/100 cm 2 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 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 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 103.13 mn 2 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 F8120 f1I1

Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F812 Fuel Storage Building Cask Catcher Pad Survey Unit: 0111 Structure Surface Class: 1 LTP Table 5-4 SU Area (m2): 103.13 Evaluator: D. Anderson DCGL (dpm/100 cm 2): 43,000 Gross Activity DCGL Area Factor: 3.2 Class 1 Design DCGLemc 137,600 Based on Co-60 as (dpm/100 cm 2): conservative value LBGR (dpm/100 cm 2): 41,689 Adjusted Design Sigma (dpm/100 cm 2): 437 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m): 6.88 Class 1 Scan Area (M2): 103.13 Scan Coverage (%): 100% Class .1 Zl-, : 1.645 ZI-P : 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: 15 Class 1 Grid Spacing L: 2.6 Class 1 Page 3 of 8 FSS Summary Report F 8120111l

Survey Results:

A total of 15 direct measurements were made in F81201 11. 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 3,367 to 40,795 dpm/100 cm 2, 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 F8120111-CO001BD 2,225 F8120111-CO002BD 2,490 F8120111-CO003BD 2,448 F8120111-C0004BD 2,179 F8120111-C0005BD 2,085 F8120111-CO006BD 2,158 F8120111 -CO007BD 2,205 F8120111-CO008BD 2,355 F8120111-CO009BD 2,345 F8120111-CO01OBD 2,246 F8120111-CO011BD 7,838 F8120111-CO012BD 2,407 F8120111-CO013BD 2,153 F8120111-CO014BD 2,256 F8120111-CO015BD 1,857 Mean: 2,616 Median: 2,246 Standard Deviation: 1,453 Range: 1.,857 - 7,838 Page 4 of 8 FSS Summary Report F812011 1

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

F8120111C0001SM 3.58 F8120111 C0002SM 6.14 F81 20111C0003SM 2.29 F8120111C0004SM -1.55 F8120111 C0005SM -0.27 F8120111 C0006SM 1.01 F8120111 C0007SM 2.29 F8120111 C0008SM 6.14 F8120111 C0009SM 7.42 F8120111CO010SM 6.14 F8120111CO011SM 2.29 F8120111CO012SM 9.98 F8120111CO013SM 7.42 F8120111CO014SM 1.01 F8120111CO015SM 4.86 Mean: 3.92 Median: 3.58 Standard Deviation: 3.27 Range: -1.55 to 9.98 Page 5 of 8 FSS Summary Report F8120 I1I1

Survey Unit Data Assessment:

The survey design required 15 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 F8120 1;11

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): 15 Median (dpm/100 cm 2): 2,246 Mean 2 (dpm/100 cm ): 2,616 Direct Measurement Standard Deviation 1,453 (dpm/100 cm 2):

Total Standard Deviation (dpm/100 cm 2): 1,453 Based on samples and backgrounds.

Maximum (dpm/100 cm 2): 7,838 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 15 S+ Value: 15 Critical Value: 11 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: Investigate No additional samples required.

Pass the Sign Test? Yes Reject the Null Hypothesis? Yes Does the Survey Unit Pass All Criteria? Investigate No additional samples required.

Page 7 of 8. FSS Summary Report F81201:11

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 F8120111 meets the release criteria of 10CFR20.1402.

Page 8 of 8 FSS Summary Report F81201111

Attachment 1 Maps April 16, 2008 Survey Unit F8120111

CD Cask Catcher Pad, South Face

'-4 1.45 m 1.qm 0j

.. .. ...- , .... -.. .... . . .. iM. .

192 . 17mI

,,° ,l E E to E LO Co.

c") 0)

-- - "I Cask Catcher Pad, East Face 5.6 m 1.85 m - 0.2 m E

tot Cask Catcher Pad, North Face

/

00 Map F8120111-1, Fuel Storage Building tQ Cask Catcher Pad Location of Cask Catcher Pad inside the Industrial Area

-4 Surface Area Estimate: 37.82 sq. meters 0 0.5 1.0 Distance in Meters

0 2.85 m

( 0.4 m 0).45 m EE oE E E Eo to U)

Cj L6 (0 6 to toto

- E E to 1 i E to 1.45 3.6__m~ 1.2m 1.9 m 6 .

0 1.0 DitnE, inMeteErsL E Cask Catcher Pad, Top Elevation 00 0 Map F8120111-2, Fuel Storage Building

- Cask-Catcher PadE

_Surface Area Estimate: 65.31 sq. meters D c in

Map F8120111-3, Fuel Storage Building Cask Catcher Pad Beta Scan Measurements F81201111C0001BS to F8120111C0044BS Juncture Scans F8120111C0001JS to F8120111C0002JS 0

Cask Catcher Pad, South Face 1..6 -575 27

..... ............

....................... ..................... 6 i.......

.......

2.... 8......

1 t: 23 26 18i 19: 20' 21 24: 25*

Cask Catcher Pad, East Face rI, 00 0 05 1.0 Cask Catcher Pad, North Face Distance in Meters

(D1 0

IT' Cask Catcher Pad, Top Elevation 00 IN Map F8120111-4, Fuel Storage Building

  • Cask Catcher. Pad ..

Beta Scan Measurements F8120111 C0045BS to F8120111 C0115BS 0Distance M.t in Meters Juncture Scans F8120111 CO003JS to F8120111 C0008JS

Map F8120111-5, Fuel Storage Building Distance in Meters Cask Catcher Pad Random Start Location 0 0.5 1.0 (Di rn ri YFJTh r 44i Ii1LLIY4T4II H-0 13~j~JAjA UIýR-Itlftlft

ýMý H +.

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F 4 4 41: M; H 0114-

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0 4-Ht~ftW4~-tH-H! IE'f 1-t+/-HfH!Ifitj~ii+/-H AH+/-f+/-tItHii-4 0 1 2 3 4 5 6 7 8 9 to 11 . 12 13

CD 0

00 Map F8120111-6, Fuel Storage Building 0 1,0 2.0 Cask Catcher Pad Distance in Meters Class 1 Beta Direct Measurements: 2.6 meter by 2.6 meter grid

00 0

Cask Catcher Pad, Top Elevation OO 0 N Map F8120111-7, Fuel Storage Building Cask Catcher Pad Class 1 Beta Direct Measurements (2.6 m grid) 0 1.0 F81201111C0001BD to F8120111C0014BD Distance in Meters

O 0,

Cask Catcher Pad, South Face It 00 Map F8120111-8, Fuel Storage Building Cask Catcher Pad- ---..

0 0.5 1.0 Distance in Meters Class 1 Beta Direct Measurement (2.6 m grid)

F8120111CO015BD

ý,T AW~

Map F8120111-9,. Fuel Storage Building Cask Catcher Pad Photos - 1 Page 10 of 12 Att. 1 Maps F8120111

Map F81 201 11-1 0, Fuel Storage Building Cask Catcher Pad Photos - 2 Page 11 of 12 Att. 1 Maps F8120111

Map F8120111-11, Fuel Storage Building Cask Catcher Pad Photos - 3 Page 12 of 12 Att. 1 Maps F8120111

Attachment 2.

Instrumentation April 16, 2008 Survey Unit F8120111

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

M2350; 180738 43-68B; 160051 433 1,033 M2350; 149802 43-68B; 148453 433 1,033 M2350; 203465 43-68/5B; 148942 433 1,033 M2350; 149802 43-116-1B; 190173 491 739 Tennelec; 0401171 N/A 5.15 dpm a, N/A 8.12 dpm 3 Table 2-2. Investigation Criteria and DCGL Value

  • Parameter (dpm/100 cm 2 )

Investigation Criteria - Direct 137,600 Investigation Criteria - Scan 137,600 DCGLw 43,000 DCGLEMC 137,600 Page 2 of 2 Att. 2 Instrumentation F8120H1

Attachment 3 Investigation April 16, 2008 Survey Unit F8120111 (none required)

Attachment 4 Data Assessment April 16, 2008 Survey Unit F8120111

FBI1201 11 Gross Activity Sample Results Quantile Plot 0 DCGL =43000 dpm/1 00cm2 9,000 5,000

>,4,000 3,000 - .$ . 4 .>-.p 2 , 0 00 .: c - *- - . - . 2 4 1,000 - - -- -

0-~.4 . .. ~ ~ ~ 4 0 20.4 ~40~4 60 80~ 10-0---

.esueens(dm10c2

.iet 4-meia 75th4 Pecntl 50tPecenil

CD 0*

F8120111 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpm/l00cm=

10000 N, 8000 0 E I 8978 oa 6000 e E 4000 p- CL

- -- -.. - -- o- -- " -" -- o 2616

> BR 2000 0 0 0 r - 0 0

< -2000 - i.a .i a ira.la.laa

- a l lr 1 -1743

-4000 t* o a a a a a) -0 0 0 a U. U U U U U U U UtU Ut) U U U Measurement Locations (00 a

k) E o Gross Activity - Average a a "+3StDev" - -"-3StDev"

F81 20111 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm2 14 13 12 C 11 0

9 LL 8 j

C 7 6

CD~

(n2 CD~

5 4

3 2

1 0

LC) 00

("1 (Y)

LC,,.,

R t'Q C) Bins - Upper End Value (dpm/l OOcm2)

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