ML090900770

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Final Status Survey Report for October 29, 2008, Tank Farm Condensate Storage Tank Pad, Survey Unit F8100041
ML090900770
Person / Time
Site: Rancho Seco
Issue date: 10/29/2008
From: Tallman D
Sacramento Municipal Utility District (SMUD)
To:
NRC/FSME
Shared Package
ML090830613 List: ... further results
References
DPG 09-097
Download: ML090900770 (30)
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Text

Rancho Seco Final Status Survey Summary Report October 29, 2008 Tank Farm Condensate Storage Tank Pad Survey Unit F8100041 Prepared By: Dan A. Tallman_______________ Date: October 29, 2008 FSS Engi eer Reviewed By. Date:- 1O tW4 Lead FSS Engineer Approved By:___ _ _ Date:  ?- -

Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8100041, Tank Farm Condensate Storage Tank Pad Survey Unit

Description:

Operating History: The area consists of the concrete pad that supported the Condensate Storage Tank (CST), used to store radioactive liquids. Included in this survey unit are several smaller concrete pads that provided foundation to various pumps and piping associated with the tankage in the tank farm. Operating records and the HSA document several events with the potential for a release of radioactivity associated with this survey area. The HSA documerited the storage of radioactive material within the area that may have had the potential to contaminate the area.

Several locations within the perimeter of the designated pads required remediation.

Site Characterization: Soil samples surrounding the survey unit were collected and analyzed for the presence of plant-derived radionuclides. Cs-137 was the primary nuclide of plant origin detected with a mean activity level of 379 pCi/g and a maximum value of 1,040 pCi/g. Based on the classification procedure (DSIP-0020) and levels of Cs-137 reported, the area was determined to be a Class 1 area.

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 195.1 m2 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 9 FSS Summary Report F8100041

Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F810 Tank Farm Condensate Storage Tank Pad Survey Unit: 0041 Structure Surface Class: 1 LTP Table 5-4 SU Area (m2): 195.1 Evaluator: D.A.Tallman DCGL (dpm/100 cm 2): 43000 Gross Activity DCGL Area Factor: 3.56 Class I Design DCGLemc 152901 Class 1 (dpm/100 cm 2 ):

LBGR (dpm/]100 cm 2): 21500 Default = 50% DCGL Design Sigma 2 (dpm/100 cm ): 7614 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): 6.96 Class I Scan Area (m2 ): 195.1 Scan Coverage (%): 100% Class I 1.645 1.645 Sign P: 0.99379 Calculated Relative Shift: 2.8 Relative Shift Used: 2.8 Uses 3.0 if Relative Shift is

>3 N-Value: 12 Design N-Value + 20%: 15 NUREG-1575 Table 5-5 Design Min Samples N: 28 Class 1 Grid Spacing L: 2.6 Class 1 Page 3 of 9 FSS Summary Report F8100041

Survey Results:

A total of 38 direct measurements were made in F8100041. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. Two of the scan measurements indicated areas of elevated activity. Scan activity ranged from 895 to 71920 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.

Page 4 of 9 FSS Summary Report F8100041

Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/100 cm

+

F8100041-CO001BD 2905 F8100041 -CO002BD 2588 F8100041-CO003BD 2588 F8100041-CO004BD .2801 F8100041-CO005BD 2189 F8100041-CO006BD *2459 F8100041 -CO007BD 2474 F8100041-CO008BD 2505 F8100041 -CO009BD 2552 F8100041-COOIOBD 2920 F8100041-Co011BD 2640 F8100041 -Co01 2BD 2952 F8100041-Cool 3BD 2547 F8100041-CO014BD 2220 F8100041-CO015BD 2677 F8100041-Co016BD 2454 F8100041-Co017BD 2454 F8100041 -Co01 8BD 2547 F8100041-CO019BD 2469 F8100041 -CO02OBD 3092 F8100041-CO021BD 2132 F8100041-CO022BD 2671 F8100041-CO023BD 2620 F8100041 -CO024BD 2474 F8100041-CO025BD 2640 F8100041-CO026BD 2355 F8100041-CO027BD 2474 F8100041-CO028BD 2957 F8100041-CO029BD 2723 F8100041-CO03OBD 2822 F8100041-C0031BD 3118 F8100041-CO032BD 2677 F8100041-CO033BD 2879 F8100041 -CO034BD 2635 F8100041 -CO035BD 2386 F8100041-CO036BD 2474 F8100041-CO037BD 2635 F8100041-CO038BD 2428 Mean: 2609 Median: 2588 Standard Deviation: 232 Ranqe: 2132-3118 Page 5 of 9 FSS Summary Report F8100041

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

F8100041 C0001 SM -3.53 F8100041C0002SM 4.22 F8100041C0003SM -3.53 F8100041 C0004SM -2.24 F8100041COOO5SM -2.24 F8100041 C0006SM -2.24 F8100041 C0007SM -2.24 F8100041C0008SM -2.24 F8100041 CO009SM -3.53 F8100041C0010SM -2.24 F8100041CO01ISM -3.53 F8100041CO0O12SM -2.24 F8100041CO013SM -3.53 F8100041CO014SM -3.53 F8100041COO15SM -3.53 F8100041COO16SM -3.53 F8100041CO017SM 2.93 F8100041COO18SM -2.24 F8100041CO019SM -4.82 F8100041C0020SM -0.95 F8100041CO021SM -3.53 F8100041C0022SM 0.34 F8100041 C0023SM -2.24 F8100041 C0024SM -4.82 F8100041 C0025SM -3.53 F8100041 C0026SM -3.53 F8100041C0027SM -3.53 F8100041 C0028SM -2.24 F8100041 C0029SM -3.53 F8100041 C0030SM -6.11 F8100041C0031SM 2.93 F8100041 C0032SM -4.82 F8100041C0033SM 4.22 F8100041C0034SM -3.53 F8100041C0035SM -3.53 F8100041 C0036SM -4.82 F8100041 C0037SM 0.34 F8100041C0038SM 6.8 Mean: -2.1 Median: -3.53 Standard Deviation: 2.85 Range: -6.11 to 6.8 Page 6 of 9 FSS Summary Report F8100041

Survey Unit Data Assessment:

The survey design required 38 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 7 of 9 FSS Summary Report F8100041

Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/1'00 cm2): N/A Ambient Background Used (dpm/100 cm 2): N/A Average Ambient BKG = 0 Actual Direct Measurements (N): 38 Median (dpm/100 cm 2 ): 2588 Mean (dpm/100 cm 2 ): 2609 Direct Measurement Standard Deviation 232 2

(dpm/100 cm ):

Total Standard Deviation (dpm/100 cm 2): 232 Based on samples and backgrounds.

Maximum (dpm/100 cm 2): 3118 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 38 S+ Value: 38 Critical Value: 24 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 8 of 9 FSS Summary Report F8100041

Survey Unit Investigations and Results:

Two investigations (JS06 and JS45) were required for the scan measurements and the results are reported in Attachment 3. The EMC unity rule was not exceeded as shown in Table 3-1.

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 I 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. Two potential areas of elevated activity were detected and evaluated as shown in Attachment 3. 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 meastirements 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. The required investigations were performed and evaluated.

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 F8100041 meets the release criteria of 10CFR20.1402.

Page 9 of 9 FSS Summary Report F8100041

Attachment 1 Maps October 29, 2008 Survey Unit F8100041

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Attachment 2 Instrumentation October 29, 2008 Survey Unit F8100041

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

M2350; 180733 43-98B; 148638 82 0 A 1490A 950B 1660 M2350; 180733 43-94B; 148620 M2350; 203482 43-68B; 178510 43-68B; 161406 1033 M2350; 189089 M2350; 193715 43-68B; 148630 M2350; 180738 43-51B; 190666 990, 2313D Tennelec; 0401171 N/A 6 dpm a, 12 dpmr N/A A43-98B penetration - metal - 4" B43-94B penetration - metal - 1" c 43-94B penetration - metal - 2" D43 -51B juncture - concrete Table 2-2. Investigation Criteria and DCGL Value d aluc Parameter (dpm/100 cm 2)

Investigation Criteria - Direct 43000 E Investigation Criteria - Scan 43000 E DCGLw 43000 DCGLEMC 152901.

ESet conservatively at DCGLw Page 2 of 2 Att. 2 Instrumentation F8100041

Attachment 3 Investigation October 29, 2008 Survey Unit F8100041

Table 3-1 Survey Unit Investigation Investigation Value Investigation Initial Elevated Area Investigation DCGLemc Area (m) aResultDCGLemc Factor Result Unity Level (cpm) (cpm) (cpm) (dpmlOOcm2) Fraction JS06 1100 1534 1534 0.01 1294.1 55,646,300 59,862 0.001 JS45 1100 1843 1843 0.20 66.89 2,876,270 71,920 0.025 Survey Unit Remainder DCGL = SU Mean = 0.061 43,000 2609 EMC Unity Sum 0.086 Page 2 of 2 Att. 3 Investigation F8100041

Attachment 4 Data Assessment October 29, 2008 Survey Unit F8100041

F8100041 Gross Activity Sample Results Quantile Plot tQ DCGL = 43000 dpm/100cm' 31500 ~. 4~44 -44 -

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