Rancho Seco

Final Status Survey Summary Report

February 11, 2009

Auxiliary Building Exterior East Wall

Survey Unit F8132143

Prepared By: 2 %\' -• Date:________

FSS Engineer

Reviewed By: \ 4 Date: "-7-c

Lead FSS Engineer

Approved By: -7 Date: 7

Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY SUMMARY REPORT

Survey Unit:F8132143, Auxiliary Building Exterior East Wall

Survey Unit Description:Operating History: The reinforced concrete structure contained the RadWaste processingand supporting systems. The building contained six main elevations. Residualradioactive 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 releaseof radioactivity inside this structure. One report documented contamination of theauxiliary building roof. The roof was later replaced;

Site Characterization: Direct measurements were made of each of the interior elevationsurfaces as well as the exterior surfaces of the structure. These measurements confirmedthe presence of plant-derived radionuclides. Direct measurements on the -47' elevationshowed a mean gross activity level of 320,071 dpm/100 cm2 and a maximum value of5,720,000 dpm/100 cm2. Direct measurements on the -29' elevation showed a meangross activity level of 544,756 dpm/100 cm2 and a maximum value of 11,370,000dpm!l 00 cm2 . Direct measurements on the -20' elevation showed a mean gross activitylevel of 247,831 dpm/100 cm2 and a maximum value of 10,080,000 dpm/100 cm 2. Directmeasurements on the grade elevation showed a mean gross activity level of 373,758dpm/100 cm 2 and a maximum value of 5,800,000 dpm/100 cm 2. Direct measurements onthe +20' elevation showed a mean gross activity level of 85,408 dpm/100 cm 2 and amaximum value of 1,900,000 dpm/100 cm2 . Direct measurements on the +40' elevationshowed a mean gross activity level of 3,288 dpm/l100 cm 2 and a maximum value of24,781 dpm/100 cm 2. Direct measurements on the building exterior, including themezzanine roof, showed a mean gross activity level of 1,897 dpm/100 cm2 and amaximum value of 2,990 dpm/100 cm 2. (The roof had been replaced prior to theclassification survey.) Based on the classification procedure (DSIP-0020) and levels ofgross activity reported, the interior of the auxiliary building was determined to be a Class1, 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 andmeasurement locations are depicted on the maps in Attachment 1. Direct measurementlocations were randomly determined and 396 m2 were scanned for approximately 97%coverage. Samples of removable contamination were collected at each directmeasurement location. The instrumentation used for the survey along with the MDCvalues are listed in Tables 2-1 and 2-2 in Attachment 2.

Page 2 of 8 FSS Summary Report F8132143

Table 1. Survey Unit Design Parameters

Survey Design Value CommentParameter

Survey Area:

Survey Unit:Class:

SU Area (mE):

Evaluator:DCGL (dpm/1O0 cm 2):

Area Factor:Design DCGLemc

(dpm/100 cm2):

LBGR (dpm/100 cm 2):

Design Sigma (dpm/100 cm 2):

Type I Error:Type II Error:

Predominant Nuclide:Sample Area (m2):

Scan Area (Mi2):

Scan Coverage (0/):

Sign P:Calculated Relative Shift:

Relative Shift Used:

N-Value:Design N-Value + 20%:Design Min Samples N:

Grid Spacina L:

F813

21433

410Gary Frank

43000N/AN/A

21500342

0.050.05

Cs-137N/A396

97%1.6451.645

0.9986562.8

3

111414

N/A

Auxiliary Building ExteriorEast Wall

Structure SurfaceLTP Table 5-4

Gross Activity DCGLClass 3Class 3

Default = 50% DCGLDTBD-06-001, Table 5-4D

Class 3

Class 3

Uses 3.0 if Relative Shift is>3

NUREG-1575 Table 5-5Class 3Class 3

Page 3 of 8 FSS Summary Report F8132143

Survey Results:A total of 14 direct measurements were made in F8132143. The results including mean,median, standard deviation and range are shown in Table 2. All direct measurementswere less than the DCGL. None of the scan measurements indicated areas of elevatedactivity. ISOCS scan activity ranged from 662 to 978 dpm/100 cm 2 for Cs-137 and 472 to739 dpm/100 cm 2 for Co-60. Samples for removable surface activity were all less than10% of the DCGL as shown in Table 3. Removable surface activity samples werecounted for alpha activity and none was detected at the MDC shown in Table 2-1 ofAttachment 2.

Table 2. Direct Measurement Results

Measurement ID Gross Activity(dpm/100 cm )

F8132143-CO001BD 1369F8132143-C0002BD 1115F8132143-C0003BD 1634F81321.43-CO004BD 1022F8132143-CO005BD 1390F8132143-CO006BD 1203F8132143-CO007BD 1437F8132143-CO008BD 1276F8132143-CO009BD 1203F8132143-CO01OBD 1053F8132143-CO011BD 1364F8132143-CO012BD 1022F8132143-CO013BD 1048F8132143-CO014BD 1261

Mean: 1243Median: 1232

Standard Deviation: 183Range: 1022 - 1634

Page 4 of 8 FSS Summary Report F8132143

Table 3. Removable Surface Activity Results

Measurement ID Surface Beta Activity(dpm/100 cm 2)

F8132143C0001SM -0.29F8132143C0002SM -0.29F8132143C0003SM 2.29F8132143C0004SM -1.58F8132143C0005SM 1F8132143C0006SM -0.29F8132143C0007SM -0.29F8132143C0008SM 1F8132143C0009SM 1F8132143C0010SM -0.29F8132143C0011SM -1.58F8132143C0012SM 2.29F8132143C0013SM -0.29F8132143C0014SM -0.29

Mean: 0.17Median: -0.29

Standard Deviation: 1.2Range: -1.58 to 2.29

Page 5 of 8 FSS Summary Report F8132143

Survey Unit Data Assessment:The survey design required 14 direct measurements for the Sign Test. The critical valueand the results of the Sign Test are presented in Table 4. The sample mean and medianvalues were less than the DCGL. The sample standard deviation was less than the designstandard deviation so no additional samples were required.

Page 6 of 8 FSS Summary Report F8132143

Table 4. Data Assessment Results

Survey Results Parameter Value Comment

Material Background Used (dpm/100 cm 2): N/AAmbient Background Used (dpm/100 cm 2): N/A Average Ambient BKG = 0

Actual Direct Measurements (N): 14Median (dpm/100 cm 2): 1232

Mean (dpm/100 cm 2) 1243Direct Measurement Standard Deviation 183

(dpm/100 cM2):

Total Standard Deviation (dpm/100 cm2): 183 Based on samples andbackgrounds.

Maximum (dpm/100 cm2): 1634Material Type: N/A Background Subtract Not

AppliedSign Test Final N Value: 14

S+ Value: 14Critical Value: 10

Sufficient Samples Collected: YesMaximum Value < DCGL: Yes

Median Value < DCGL: YesMean Value < DCGL: Yes

Maximum Value < DCGLemc: N/A Class 3Total Standard Deviation <= Sigma: Yes

Pass the Sign Test? YesReject the Null Hypothesis? Yes

Does the Survey Unit Pass All Criteria? Yes I

Page 7 of 8 FSS Summary Report F8132143

Survey Unit Investigations and Results:No investigations were required for either direct or scan measurements and noinvestigation results are reported.

ALARA Statement:As stated in Chapter 4 of the LTP, as long as the residual activity within the survey unit isless than the DCGL, the ALARA criterion has been met.

Changes in Initial Survey Unit Assumptions:The survey unit was designed as a Class 3 structure survey and the sample results areconsistent with that classification. The variability of the survey results was less than thecharacterization data used for survey design. No potential areas of elevated activity weredetected.

Conclusion:The FSS of this survey unit was properly designed as a Class 3 survey based on Table 5-4of the LTP. The required number of direct measurements was made and the scancoverage met the requirement of Table 5-6 of the LTP. No direct measurements exceededthe DCGL of 43000 dpm/100 cm2 and none of the removable surface activitymeasurements exceeded 10% of the DCGL. No investigations were required.

The direct measurement data support rejection of the null hypothesis, providing highconfidence that the survey unit satisfied the release criteria and that thedata qualityobjectives were met.

It is concluded that survey unit F8132143 meets the release criteria of 1OCFR20.1402.

Page 8 of 8 FSS Summary Report F8132143

Attachment 1

Maps

February 11, 2009

Survey Unit F81321,43

CD

Auxiliary Building East Wall-ISOCS Scans

East end of south wall* i included in this survey...

ciNot In

*63 C

**,. // /This Survey ,,N/j /4//.

20' Reflected Overhang// ///-/ '"/// /'•/ /$/6,'785 ft'

7219 nl Aus, Bldg Ext East WallLooking West

3,629 ft'33779 P

00

FI34-

F8132143-M

(DAuxiliary Building East Wall

Beta Direct

00

70-

65 --

60-

55--

50-

457

40-

35--

307-

25-

207-

15-

10--

.5--

07

'OT

03

09

L05 L__] )6

Bottom of overhang04

11 1310

08

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135

eF8132143-M2

Attachment 2

Instrumentation

February 11, 2009

Survey Unit F8132143

Table 2-1. Survey Unit Instrumentation

Instrument Detector MDC Static MDC ScanModel; Serial No. Model; Serial No. (dpm/100 cm2 ) (dpm/100 cm2 )

M2350; 149789 43-68B; 161415 433 1033

Tennelec; 0401171 N/A 5 dpmu a, 11 dpmr3 N/A

0N/A N/A 978 Cs-137ISOCS; 1893920 N739 Co-60

Table 2-2. Investigation Criteria and DCGL

ValueParam eter V l eC 2(dpm/100 cm 2)

Investigation Criteria - Direct 21500

Investigation Criteria- Scan 43000

DCGLw 43000

DCGLEMC N/A

Page 2 of 2 Att. 2 Instrumentation F8132143

Attachment 3

Investigation

February 11, 2009

Survey Unit F8132143

(none required)

Attachment 4

Data Assessment

February 11, 2009

Survey Unit F8132143

IiG

0

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(TI

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F8132143 Gross Activity Sample Results Quantile PlotDCGL = 43000 dpm/100cm2

I4-

1,800

1,600

1,400

1,200

1,000

800

600

400

200

n

1232

T IJ I I !

0 20 40 60 80 100

PercentileSDirect Measurements (dpm/1 Ocm2) median 75th Percentile - - - - 50th Percentile

CD('3

a F8132143 Gross Activity Sample Results Scatter PlotDCGL = 43000 dpmll00cm=

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F81 32143 Gross Activity Frequency PlotDCGL = 43000 dpm1l 00cm2

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