ML090850550

Final Status Survey Summary Report 07/17/08, Turbine Building (+) 0' El., North Floor, Survey Unit F8260161

ML090850550
Person / Time
Site:	Rancho Seco
Issue date:	07/17/2008
From:	Donna Anderson Sacramento Municipal Utility District (SMUD)
To:	NRC/FSME
Shared Package
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References
DPG 09-097, F8260161
Download: ML090850550 (20)

Text

Rancho Seco Final Status Survey Summary Report July 17, 2008 Turbine Building (+) 0' El., North Floor Survey Unit F8260161 Prepared By: Reviewed By__ ._ _ __ _ _. _ __ _Date: 11/7/i0o " FSS Engineer Lead SSEgineDate:r Lead FSS Engineer Approved By: Date: Dismantlement S'4erintendent, Radiological FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit: F8260161, Turbine Building (+) 0' El. North Floor 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/l100 cm 2 and a maximum value of 24,900 dpm/1 00 cm 2.Direct measurements on the grade elevation showed a mean gross activity leyel 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.During characterization surveys of F8260131 (Turbine Building (+) 0' El., North Floor, Class 2), beta measurements identified activity within a 2-meter by 3-meter area that exceeded the DCGL of 43,000 dpm/100 cm 2.The area was subsequently remediated and reclassified as a Class 1 structure, based on the classification procedure (DSIP-0020).

As a result of the reclassification, a new survey package was initiated as F8260161.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 11.6 m 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 F8260161 Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F826 Survey Unit: Class: SU Area (m 2): 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 (%): ZlI, : ZI-0 : Sign P: Calculated Relative Shift: Relative Shift Used: N-Value: Design N-Value + 20%: Design Min Samples N: Grid Spacing L: 0161 1 11.6 D. Anderson 43,000 17.7 761,100 25,030 5,990 0.05 0.05 Cs-137 0.7 11.6 100%1.645 1.645 0.99865 3 3 11 14 14 0.9 Turbine Building (+) 0' El.North Floor Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class 1 Adjusted Class 1 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 F8260161 Survey Results: A total of 15 direct measurements were made in F8260161.

The results including mean, median, standard deviation and range are shownin Table 2. All direct measurements were less than the DCGL. None of the scan measurements indicated areas of elevated activity.

Scan activity ranged from 3,236 to 20,988 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 Activit (dpm/100 cm F8260161-CO001BD F8260161-CO002BD F8260161-CO003BD F8260161 -CO004BD F8260161 -CO005BD F8260161-CO006BD F8260161-CO007BD F8260161-C0008BD F8260161-CO009BD F8260161-Co01OBD F8260161-Co01o1 BD F8260161-Co012BD F8260161-Co013BD F8260161-CO014BD F8260161-CO015BD Mean: Median: Standard Deviation:

Range: 1,401 2,692 1,909 1,442 1,452 1,395 1,452 7,672 1,344 2,397 3,496 2,277 6,811 1,499 1,515 2,584 1,515 1,995 1,344 -7,672 Page 4 of 8 FSS Summary Report F8260161 Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)F8260161C0001SM F8260161 C0002SM F8260161 C0003SM F8260161CO004SM F8260161 C0005SM F8260161 C0006SM F8260161 C0007SM F8260161 C0008SM F8260161CO009SM F8260161Co010SM F8260161C0011SM F8260161 C001 2SM F8260161C0013SM F8260161CO014SM F8260161Co015SM Mean: Median: Standard Deviation:

Range:-3.53-4.82-3.53 0.34-2.24-6.11-0.95-3.53-2.24-3.53-2.24-3.53-3.53-0.95 0.34-2.67-3.53 1.8-6.11 to 0.34 Page 5 of 8 FSS Summary Report F8260161 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 less than the design standard deviation so no additional samples were required.Page 6 of 8 FSS Summary Report F8260161 Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm'): 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): 1,515 Mean (dpm/100 cm 2): 2,584 Direct Measurement Standard Deviation 1,995 (dpm/ 100 cm 2): Total Standard Deviation (dpm/100 cm 2): 1,995 Based on samples and backgrounds.

Maximum (dpm/100 cm 2): 7,672 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: 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 F8260161 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 wasdesigned as a Class 1 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. 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 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 F8260161 meets the release criteria of 1OCFR20.1402.

Page 8 of 8 FSS Summary Report F8260161 Attachment 1 Maps July 17, 2008 Survey Unit F8260161 0.il DLIFII"F-0 0 1 I J ii]LII-5 a'00 D 00 o] n 00 [00 [n RD Rn I I 0 N Location of Turbine Building inside the Industrial Area 0I1 00 ON N Map F82601.61-1, North Turbine Building (+) 0 Elevation Class 1 Area (floor)Area Estimate:

11.6 square meters 0 2 4 6 Distance in Meters CD 0 t)ON N 0 0.25 0.5 0.75 1.0 Distance in Meters Map F8260161-2, North Turbine Building (+) 0 Elevation Class 1 Area Random Start Location (D fjA Distance in meters from East wall 0.6 m 1.3 m 2.0 m EE () z 019 C: E E E E-~CO.o 00 ONk ON N Map F8260161-3, North Turbine Building (+) 0' Elevation Class 1 Area Beta Direct Measurements F8260161 C0001BD to F8260161 C0015BD 0.7 m by 0.7 m cgrid spacing 0 025 0.5 0.75 Distance in Meters 1.0 0 (II 00 N Map F8260161-4, North Turbine Building (+) 0' Elevation Class 1 Area Beta Scan Measurements F8260161C0001 BS to F8260161 C0006BS Juncture Scan Measurements F8260161C0001JS to F8260161C0004JS I .0 0,25 0.5 0.75 Distance in Meters 1.0 Attachment 2 Instrumentation July 17, 2008 Survey Unit F8260161 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; 193715 43-68B; 148630 433 1,033 M2350; 193715 43-116-IB; 190643 491 739 Tennelec; 0401171 N/A 5.88 dpm c N/A 11.71 dpm Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2)Investigation Criteria -Direct 761,100 Investigation Criteria -Scan 761,100 DCGLw 43,000 DCGLEMC 761,100 Page 2 of 2 Att. 2 Instrumentation F8260161 Attachment 3 Investigation July 17, 2008 Survey Unit F8260161 (none required)

Attachment 4 Data Assessment July. 17, 2008 Survey Unit F8260161 F8260161 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm 2 8,000 7,000 7,000+7,00 5,000 , 4,000 CO)° r<3,000 -2,000 0 -0 20 40 60 80 100 Percentile

• Direct Measurements (dpm/100cm2)

-median -75th Percentile 50th Percentile ON _

(tQ 0 U)o F8260161 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpm100=cn 10000 o" 8000 o oo6000 4000 o 00-2000-20000000000 o 0 0 0 0 0 0 0 0) 0 0 0 0 0 o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 U U U U U U U U U U U U U U U Measurement Locations Gross Actt Average "+3StDev" -"-3StDev.r-A: T : T TT: : :T ::::: T :T " : .: T: " T : :1: : : : ::T T: T T .: : ::Y T : ...; " : :: 1 ::::: I: i: 11i1T 1 1 CDQ 0 F8260161 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm 2 9 8 7 6 Cl)0 Cd)0 6" U-C 0 5 4-3-2-1 0 ('4 C%'I (NJ N-(0 Ir1 00 CO ON Bins -Upper End Value (dpm/100cm2)