ML090900772

Final Status Survey Summary Report for February 26, 2009, Tank Farm - Bwst Pad, Survey Unit F8100043

ML090900772
Person / Time
Site:	Rancho Seco
Issue date:	02/26/2009
From:	Tallman D Sacramento Municipal Utility District (SMUD)
To:	NRC/FSME
Shared Package
ML090830613	List: ML090830313 ML090830314 ML090830316 ML090830318 ML090830319 ML090830320 ML090830321 ML090830322 ML090830323 ML090830324 ML090830541 ML090830542 ML090830543 ML090830544 ML090830545 ML090830546 ML090830547 ML090830548 ML090830573 ML090850549 ML090850550 ML090850551 ML090850552 ML090850553 ML090850554 ML090850555 ML090850556 ML090850557 ML090850558 ML090850559 ML090850560 ML090850561 ML090850562 ML090890534 ML090890535 ML090890536 ML090890537 ML090890539 ML090890584 ML090890585 ML090890586 ML090890587 ML090890588 ML090890727 ML090900729 ML090900730 ML090900731 ML090900732 ML090900733 ML090900770 ... further results
References
DPG 09-097
Download: ML090900772 (25)

Text

Rancho Seco Final Status Survey Summary Report February 26, 2009 Tank Farm - BWST pad Survey Unit F8100043 Prepared By: Dan A. Tallman A_______________

Date: February 26, 2009 FSSEngin/eer Reviewed By:

J l

t I.*)kDate:

-[3(30 Lead FSS Engineer Approved By:

t1 Date:

Dismantlement(Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8100043, Tank Farm - BWST pad Survey Unit

Description:

Operating History: This survey unit consists of the concrete pad that supported the Borated Water Storage Tank (BWST), used to store radioactive liquids. Operating records and the HSA document several events with the potential for a release of radioactivity associated with this survey area. The HSA documented the storage of radioactive material within the area that may have had the potential to contaminate the area.

Several locations adjacent to the designated pad required remediation as did the majority of the pad itself.

Site Characterization: Soil samples surrounding the pad were collected and analyzed for the presence of plant-derived radionuclides. Cs-137 was the primary nuclide of plant origin detected. The BWST pad was surveyed by with a mean activity level of 11,992 2

2 dpm/100 cm 2 and a maximum value of 140,880 dpm/100 cm. Based on the classification procedure (DSIP-0020) and levels of Cs-137 reported, the BWST Pad 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 187 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 8 FSS Summary Report F8100043

Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area:

Survey 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 cm2):

Type I Error:

Type II Error:

Predominant Nuclide:

Sample Area (m2):

Scan Area (M2):

Scan Coverage (%):

Zl-,, :

ZI.* :

Sign P:

Calculated Relative Shift:

Relative Shift Used:

N-Value:

Design N-Value + 20%:

Design Min Samples N:

Grid Spacing L:

F810 0043 1

187 D.A.Tallman 43000 3.5 153669 21500 12845 0.05 0.05 Cs-137 6.9 187 100%

1.645 1.645 0.945201 1.6 1.6 14 17 27 2.6 Tank Farm - BWST pad Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class I Default 50% DCGL 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 F8100043

Survey Results:

A total of 27 direct measurements were made in F8100043. 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 1754 to 20819 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)

F8100043-CO001BD F8100043-CO002BD F8100043-CO003BD F8100043-CO004BD F8100043-CO005BD F8100043-CO006BD F8100043-CO007BD F8100043-CO008BD F8100043-CO009BD F8100043-COOIOBD F8100043-COOI1BD F8100043-C001 2BD F8100043-CO01 3BD F8100043-CO014BD F8100043-CO01 5BD F8100043-CO01 6BD F8100043-CO017BD F8100043-CO018BD F8100043-CO019BD F8100043-C0020BD F8100043-C0021 BD F8100043-CO022BD F8100043-CO023BD F8100043-C0024BD F8100043-CO025BD F8100043-C0026BD F8100043-CO027BD Mean:

Median:

Standard Deviation:

Range:

1976 1940 2791 2231 2007 2033 2039 2158 2044 2111 1966 2065 2023 2065 2080 2153 2065 1950 2256 2033 2054 1987 2142 2158 2085 2205 1779 2089 2065 172 1779 -2791 Rag:17929 Page 4 of 8 FSS Summary Report F8100043

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

F8100043C0001 SM F8100043C0002SM F8100043C0003SM F8100043C0004SM F8100043C0005SM F8100043C0006SM F8100043C0007SM F8100043C0008SM F8100043C0009SM F8100043C0010SM F8100043C001 1 SM F8100043C0012SM F8100043C0013SM F8100043C0014SM F8100043C0015SM F8100043C0016SM F8100043C0017SM F8100043C0018SM F8100043C0019SM F8100043C0020SM F8100043C0021SM F8100043C0022SM F8100043C0023SM F8100043C0024SM F8100043C0025SM F8100043C0026SM F8100043C0027SM F8100043C0008SM F8100043C0023SM Mean:

Median:

Standard Deviation:

Range:

-2.88

-0.29 3.58 2.29 2.29 2.29 2.29

-2.88 2.29

-1.58

-1.58 1

2.29 2.29

-0.29

-0.29 4.87 4.87

-0.29 3.58 1

2.29

-0.29 1

2.29 1

4.87 6.16

-1.58 1.4 2.29 2.34

-2.88 to 6.16 Page 5 of 8 FSS Summary Report F8100043

Survey Unit Data Assessment:

The survey design required 27 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 F8100043

Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm2):

N/A Ambient Background Used (dpm/O00 cm2):

N/A Average Ambient BKG = 0 Actual Direct Measurements (N):

27 Median (dpm/100 cm 2):

2065 Mean (dpm/100 cm 2):

2089 Direct Measurement Standard Deviation 172 (dpm/100 cm 2):

Total Standard Deviation (dpm/100 cm 2):

172 Based on samples and backgrounds.

Maximum (dpm/100 cm 2):

2791 Material Type:

N/A Background Subtract Not Applied Sign Test Final N Value:

27 S+ Value:

27 Critical Value:

18 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 F8100043

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 unitaverage 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 less than the characterization data used for survey design. No potential areas of elevated activity were detected.

==

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 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 F8100043 meets the release criteria of 10CFR20.1402.

Page 8 of 8 FSS Summary Report F8100043

Attachment I Maps February 26, 2009 Survey Unit F8100043

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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; 189089 43-68B; 161406 433 1033 M2350; 175834 43-68B; 148634 433 1033 M2350; 203482 43-68B; 148453 433 1033 M2350; 175834 43-116-1B; 190642 796 3258 M2350; 189081 44-159; 238368 5250 N/A Tennelec; 0401171 N/A 5 dpm a, 9 dpm r3 N/A Table 2-2. Investigation Criteria and DCGL Value Parameter Valuc (dpm/1,00 cm2)

Investigation Criteria - Direct 152901 Investigation Criteria - Scan 43,0001 DCGLw 43000 DCGLEMC 152901 IL set at DCGLw for conservatism Page 2 of 2 Att. 2 Instrumentation F8100043 Investigation February 26, 2009 Survey Unit F8100043 (none required)

Data Assessment February 26, 2009 Survey Unit F8100043

CD2 00 F8100043 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1OOcm 2 I

3,000 2,500 2,000 1,500 1,000 2065 500 0

0 20 40 60 80 100 Percentile I

Direct Measurements (dpm/100crn2)

-median

- -75th Percentile

- 50th Percentile I

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-O FP100043 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmll00cm Ln0 (C

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F8100043 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm 2 20-18-0i 16-14-12-10-8-

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Bins - Upper End Value (dpm/100cm2)