ML081610166

Final Status Survey Summary Report, April 1, 2008, Misc. Waste Tank Room, Room 17, Survey Unit F8130191

ML081610166
Person / Time
Site:	Rancho Seco
Issue date:	04/01/2008
From:	Ellen Brown Sacramento Municipal Utility District (SMUD)
To:	NRC/FSME
References
F8130191
Download: ML081610166 (26)

Text

Rancho Seco Final Status Survey Summary Report April 1, 2008.

Misc. Waste Tank Room, Room 17 Survey Unit F8130191 Prepared By:____

Date: Ili 12DO

!SS n",jieer Reviewed By:

Date:

LeadSS Engineer Approved By:

Date:

Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8130191, Misc. Waste Tank Room, Room 17 Survey Unit

Description:

Operating History: The reinforced concrete structure contained the RadWaste processing and supporting systems. The building contained six main elevations. Residual radioactive material was known to be present on all levels of the interior of the building.

Operating records andithe HSA document several events with the potential for a release of radioactivity inside this structure. One report documented contamination of the auxiliary building roof. The roof was later replaced.

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 -47' elevation showed a mean gross activity level of 320,071 dpm/100 cm 2 and a maximum value of 5,720,000 dpm/l100 cm 2. Direct measurements on the -29' elevation showed a mean gross activity level of 544,756 dpm/100 cm 2 and a maximum value of 11,370,000 dpm/100 cm 2. Direct measurements on the -20' elevation showed a mean gross activity level of 247,831 dpm/I00 cm2 and a maximum value of 10,080,000 dpm/100 cm 2. Direct measurements on the grade elevation showed a mean gross activity level of 373,758 dpm/100 cm 2 and a maximum value of 5,800,000 dpm/100 cm 2. Direct measurements on the +20' elevation sho~ved a mean gross activity leVel of 85,408 dpm/100 cm 2 and a maximum value of 1,9.00,000 dpm/l00 cm 2. Direct measurements on the +40' elevation showed a mean gross activity level of 3,288 dpm1O00 cm2 and a maximum value of 24,781 dpml100 cm2.i Direct measurements on the building exterior, including the mezzanine roof, showed a mean gross activity level of 1,897 dpm/100 cm 2 and a maximum value of 2,9290 dpm/1 00 cm 2. (The roof had been replaced prior to the classification survey.) Based on the classification procedure (DSIP-0020) and levels of gross activity reportedi the interior of the auxiliary building was determined to be a Class 1, 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 1 below. The survey unit and measurement location' are depicted on the maps in Attachment 1. Direct measurement locations were determined using a random-start, fixed grid pattern and 167 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 F8130191

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

F813 Survey Unit:

Class:

SU Area (m2):

Evaluator:

DCGL (dpm/100 cm 2):

Area Factor:

Design DCGLemc (dpm/1O0 cm 2):

LBGR (dpm/100 cm2):

Design Sigma (dpm/100 cm2):

Type I Error:

Type 1I Error:

Predominant Nuclide:

Sample Area (m2):

Scan Area (m2):

Scan Coverage (%):

Sign P:

Calculated Relative Shift:

Relative Shift Used:

N-Value:

Design N-Value +20%:

Design Min Samples N:

Grid Spacing L:

0191 1

167 Erin L. Brown 43000 3.3 141900 21500 12035 0.05 0.05 Cs-137 6.9 167 100%

1.645 1.645 0.955435 1.7 1.7 14 17

'24 2.6 Misc. Waste Tank Room, Room 17 Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class 1 Default = 50% DCGL Class I Class 1 Uses 3.0 if Relative Shift is

>3 NUREG-1575 Table 5-5 Class 1 Class I Page 3 of 8 FSS Summary Report F8130191

Survey Results:.

A total of 25 direct measurements were made in F8130191. 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 1496 to 132853 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 Activity (dpm/100 cm F8130191-CO001BD F8130191 -CO002BD F8130191-C0003BD F8130191 -CO004BD F8130191 -CO005BD4 F8130191 -CO006BD F8130191-CO007BD F8130191-CO008BD F8130191-CO009BD F8130191-CO01OBD F8130191-CO011BD F8130191-CO012BD F8130191-CO013BD F8130191-CO014BD F8130191-CO015BD F8130191-CO016BD F8130191--Co017BD F8130191-CO018BD F8130191-CO019BD F8130191-CO02OBD F8130191 -CO021 BD F8130191-CO022BD F8130191 -CO023BD F8130191 -CO024BD F8130191-CO025BD Mean:

Median:

Standard Deviation:

Rancie:I 2516 2454 2116 2215 4762 4430 2080 2070 1899 2023 2049 2345 1644 2101 2422 1930 2070 2002 1764 1987 2334 2065 2054 1987 2039 2294 2070 723 1644 -4762 Ranqe:

1644 -4762 Page 4 of 8 FSS Summary Report F8130191

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

F8130191COOOISM 11.97 F8130191 C0002SM 1.64 F8130191C0003SM 6.8 F8130191 C0004SM 30.05 F8130191C0005SM 4.22 F8130191C0006SM 10.68 F8130191 C0007SM

-0.95 F8130191 C0008SM 6.8 F8130191,C0009SM 77.83 F8130191CO010SM 9.38 F8130191 C0011 SM 13.26 F8130191C0012SM 10.68 F8130191C0013SM

-0.95 F8130191C0014SM 0.34 F8130191C0015SM 13.26 F8130191C0016SM 5.51 F8130191COO17SM 5.51 F8130191C0018SM 6.8 F8130191C0019SM 18.42 F8130191 C0020SM 0.34 F8130191C0021SM 14.55 F8130191 C0022SM

-3.53 F8130191C0023SM

-0.95 F8130191C0024SM 1.64 F8130191C0025SM 4.22 Mean:

9.9 Median

6.8 Standard Deviation:

15.98 Range:

-3.53 to 77.83 Page 5 of 8 FSS Summary Report F8130191

Survey Unit Data Assessment:

The survey design required 25 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 F8130191

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):

25 Median (dpm/100 cm 2):

2070 Mean (dpm/100 cm2):

2294 Direct Measurement Standard Deviation 723 (dpm/100 cm 2):

Total Standard Deviation (dpm/100 cm 2):

723 Based on samples and backgrounds.

Maximum (dpm/100 cm 2):

4762 Material Type:

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

25 S+ Value:

25 Critical Value:

17 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 F8130191

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 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 F8130191 meets the release criteria of 10CFR20.1402.

Page 8 of 8 FSS Summary Report F8130191 Maps April 1, 2008 Survey Unit F8130191

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-La~Z.SHEET 3 00 TC HILL Instrumentation April 1, 2008 Survey Unit F8130191

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 N/A 1490 M2350; 175834 43-68B; 190482 433 1033 M2350; 175834 43-116-1B; 190642 N/A 3258 Tennelec; 0401171.

N/A 5.9 dpm a, N/A 11.7 dpm Inspector N/A N/A 2113 Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2)

Investigation Criteria - Direct 141900 Investigation Criteria - Scan 141900 DCGLw 43000 DCGLEMC 141900 Page 2 of 2 Att. 2 Instrumentation F.8130191 Investigation April 1, 2008 Survey Unit F8130191 (none required)

Data Assessment April 1, 2008 Survey Unit F8130191

F8130191 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm 2 4Y50 5,000 -

4,500 4,000 MI

• -:2 07 0 w2,000 p.P.

1,0 50~

0 20 40 60 80 100 Percentile

• Direct measurements (dpm/1 O0cm2) median..-

-75th Percentile ---- 50th Percentile

CD 0

oF8130191 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmlO00cm 2 5000 0

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