ML090930663

Final Status Survey Summary Report for February 10, 2009, Containment Building Exterior Walls, Survey Unit F8113001

ML090930663
Person / Time
Site:	Rancho Seco
Issue date:	02/10/2009
From:	Sacramento Municipal Utility District (SMUD)
To:	NRC/FSME
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References
DPG 09-097
Download: ML090930663 (19)

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Rancho Seco Final Status Survey Summary Report February 10, 2009 Containment Building Exterior Walls Survey Unit F8113001 Prepared By:6 62, cC Date:_________

FSS Engineer Reviewed By: _ _ _ _ _Date: " -Ov Lead FSS Engineer-77 Approved By: e Date: -c9 c-Dismantlement Superintendent, Radiological FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit: F8113001, Containment Building Exterior Walls Survey Unit

Description:

Operating History:

The reinforced concrete structure contained the reactor and supporting systems. The building contained four 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.

No events documenting exterior contamination were found.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 -27' elevation showed a mean gross activity level of 1,535,383 dpm/100 cm 2 and a maximum value of 8,134,000 dpm/100 cm 2.Direct measurements on the grade elevation showed a mean gross activity level of 201,670 dpm/100 cm 2 and a maximum value of 370,000 dpm/100 cm 2.Direct measurements on the +40' elevation showed a mean gross activity level of 51,521 dpm/100 cm 2 and a maximum value of 99,150: dpm/-100 cm 2.Direct measurements on the +60' elevation showed a mean gross activity level of 20,110 dpm/100 cm 2 and a maximum value of 46,660 dpm/100 cm 2.Direct measurements on theexterior roof showed a mean gross activity level of 1,364 dpm/100 cm 2 and a maximum value of 1,571 dpm/100 cm 2.Based on thel classification procedure (DSIP-0020) and levels of gross activity reported, the interior of the reactor building was determined to be a Class 1 area and the exterior waý 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 locations were randomly determined and 1158 m 2 were scanned for approximately 21%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 F8113001 Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F811Survey Unit:

Class: SU Area (m2): Evaluator:

DCGL (dpm/100 cm 2): Area Factor: Design DCGLemc (dpm/100 cm 2): LBGR (dpm/100 cm 2): Design Sigma (dpm/100 cm 2): Type I Error: Type II Error: Predominant Nuclide: Sample Area (m2): Scan Area (M 2): Scan Coverage (%): Zl-, : Sign P: Calculated Relative Shift: Relative Shift Used: N-Value: Design N-Value + 20%: Design Min Samples N: Grid Spacing L: 3001 3 5516Gary Frank 43000 N/A N/A 21500 119 0.05 0.05 Cs-137 N/A 1158 21%1.645 1.645 0.9,9865 180.6 3 11 14 14 N/AContainment Building Exterior Walls Structure Surface LTP Table 5-4 Gross Activity DCGL Class 3 Class 3 Default = 50% DCGL Class 3 Class 3 Uses 3.0 if Relative Shift is>3 NUREG-1575 Table 5-5 Class 3 Class 3 Page 3 of 8 FSS Summary Report F8113001 Survey Results: A total of 14 direct measurements were made in F8113001.

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 measurerrments indicated areas of elevated activity.

Scan activity with 2350-1 w/ 43-68B ranged from 3807 to 7593 dpm/100 cm 2 , based on a surveyor efficiency of 0.5 and no background subtracted.

ISOCS scans ranged from 725 to 943 dpm/100cm 2 for Cs-137 and 443 to 783 dpm/100cm 2 for Co-60.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 F8113001-CO001BD 1504 F8113001-CO002BD 1426 F8113001-CO003BD 1328 F8113001-CO004BD 1494 F8113001-CO005BD 1250 F8113001-CO006BD 1385 F8113001-CO007BD 1266 F8113001-CO008BD 1447 F8113001-CO009BD 1359 F8113001-CO01OBD 1364 F8113001-CO011BD 1266 F8113001-CO012BD 1281 F8113001-CO013BD 1473 F8113001-CO014BD 1401 Mean: 1375 Median: 1375 Standard Deviation:

88 Range: 1250-1504 Page 4 of 8 FSS Summary Report F8113001 Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)F8113001C0001SM

-0.29 F8113001C0002SM

-0.29 F8113001C0003SM 1 F8113001 C0004SM 1 F8113001C0005SM 3.58 F8113001 C0006SM 1 F8113001 C0007SM 1 F8113001 C0008SM 1 F8113001C0009SM

-0.29 F8113001CO010SM

-0.29 F8113001C0011SM 3.58 F8113001CO012SM 2.29 F8113001CO013SM

-0.29 F8113001COO14SM 1 Mean: 1 Median: 1 Standard Deviation:

1.34 Range: -0.29 to 3.58 Page 5 of 8 FSS Summary Report F8113001 Survey Unit Data Assessment:The survey design required 14 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 F8113001 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): 14 Median (dpm/100 cm 2): 1375 Mean (dpm/100 cm 2): 1375 Direct Measurement Standard Deviation 88 (dpm/100 cm 2): Total Standard Deviation (dpm/100 cm 2): 88 Based on samples and backgrounds.

Maximum (dpm/100 cm 2): '1504 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 14 S+ Value: 14 Critical Value: 10 Sufficient Samples Collected:

Yes Maximum Value < DCGL: Yes Median Value < DCGL: Yes Mean Value < DCGL: Yes Maximum Value < DCGLemc: N/A Class 3 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 F8113001 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, 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 are consistent with that classification.

The variability of the survey results was less than the characterization data used for survey design.Conclusion:

The FSS of this survey unit was properly designed as a Class 3 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 43000 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 F8113001 meets the release criteria of 1OCFR20.1402.

Page 8 of 8 FSS Summary Report F8113001 Attachment 1 Maps February 10, 2009 Survey Unit F8113001 0 Containment Exterior N[;'0 Nt,.~ 53 S 330 230 laX i tm~~93090 00,~ Uaostll90Ol -R..dOO.103'AWS It 00 W, F8113001 -M1 0 270.21-120 E53.4t44 0'1 O'Ol 45*40 35 30 20 -15 6 10 13.3 5 " 4.44 8.4m----- 1Y.2 m ti 41 44 0' 4 it'I 4.4{' ~? ..~ 4~~1 0 44 01 04 d 44 F~7~ "1 jO'<3 ~- 4~4 07 4 0.4 mi ;7.4m T, si ~ b 2 2 6m L A407ry 744-2'433'.....I ...I .....5 ....I ...I .......I ....I ....I ....I ....I ....I 7.0 5I '5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 58.537 R'54384344W4*F 04d h: /E4044 M~psMI 13001 -Rooc0 &41054A5WF 00 w F8113001-M2 CD 4f) Reactor Building Emergency Hatch Interior Beta Scans Ceiling 24]South Wall Floor 2 31 06 0o91[18] IQfilJ- 13 North Wall 00 F8113001-M3 Attachment 2 Instrumentation February 10, 2009 Survey Unit F8113001 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; 149789 43-68B; 161415 433 1033 M2350; 175834 43-68B; 148634 433 1033 Tennelec; 0401171 N/A 5 dpm ct, 10 dpm N/A Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2)Investigation Criteria -Direct 21500 Investigation Criteria -Scan 43000 DCGLw 43000 DCGLIBMC N/A Page 2 of 2 Att. 2 Instrumentation F8113001 Attachment 3 Investigation February 10, 2009 Survey Unit F8113001 (none required)

Attachment 4 Data Assessment February 10, 2009 Survey Unit F8113001 cIQ 0 Uy)00 UjJ F8113001 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm 2 I 4-3 1,600 1,400 1,200 1,000 800 600 400 200 0 1375 0 20 40 60 80 100 Percentile Direct Measurements (dpm/100cm2) -m edian ---75th Percentile

-50th Percentile]

CD w o FBI113001 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmlloocma 1800 1 0 o 0 E 1400 1375 0 00 0 0> g1200 -1112 E 0- -111 o n tSoo 0 400 a 4 200 0 V- Cl fq to 0 0 0 0 0 0 0 0 0 0 So 0 0 0 0 0 0 0 V0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 000 0 00 0 000 0 0 U U U U U U U U- U U U U U U Measurement Locations 1 o Gross Activity -Average --"+3StDev ... "-3StDev 0 0 D-e 00 C)0*F811 3001 Gross Activity Frequency Plot DCGL = 43000 dpml/ 00cm 2 LL 0)U-0 8 7 6 5 4 3 2 1 0 Bins -Upper End Value (dprn/lOOcm2)