ML090980383

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Final Status Survey Summary Report for November 5, 2008 West Decay Heat Removal Pump Room - Ceiling Survey Unit F8130022
ML090980383
Person / Time
Site: Rancho Seco
Issue date: 11/05/2008
From: Tallman D
Sacramento Municipal Utility District (SMUD)
To:
NRC/FSME
Shared Package
ML090830613 List: ... further results
References
DPG 09-097
Download: ML090980383 (23)
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Rancho Seco Final Status Survey Summary Report November 5, 2008 West Decay Heat Removal Pump Room - Ceiling Survey Unit F8130022 Prepared By: Dan A. Tallman Date: November 5, 2008 FSS Engneer Reviewed By:

Date:

I1 (3C* O Lead FSS Engineer Approved By:

Date:

Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8130022, West Decay Heat Removal Pump Room - Ceiling Survey Unit

Description:

Operating History: The Auxiliary Building was a reinforced concrete structure that 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 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 on the -47' elevation showed a mean gross activity level of 320,071 dpm/100 cm2 and a maximum value of 5,720,000 dpm/100 cm 2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the Ceiling of the West Decay Heat Removal Pump Room in the interior of the auxiliary building was determined to be a Class 1 area.

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 95 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 F8130022

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/100 cm 2):

LBGR (dpm/100 cm2):

Design Sigma (dpm/100 cm2):

Type I Error:

Type II Error:

Predominant Nuclide:

Sample Area (m2):

Scan Area (m2):

Scan Coverage (%):

ZI, :

Sign P:

Calculated Relative Shift:

Relative Shift Used:

N-Value:

Design N-Value + 20%:

Design Min Samples N:

Grid Spacing L:

0022 1

95 D.A.Tallman 43000 3.78 162540 21500 9976 0.05 0.05 Cs-137 6.3 95 100%

1.645 1'.645 0.97725 2.2 2.2 12 15 15 2.5 West Decay Heat Removal Pump Room - Ceiling Structure Surface LTP Table 5-4 Gross Activity DCGL Class I Class 1 Default = 50% DCGL Class I Class 1 Uses 3.0 if Relative Shift is

>3 NUREG-1575 Table 5-5 Class I Class 1 Page 3 of 8 FSS Summary Report F8130022

Survey Results:

A total of 19 direct measurements were made in F8130022. 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 1310 to 2450 dpm/100 cm2, based on In-Situ gamma spec results for the licensed radioactive material detected. 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 F8130022-CO001BD F8130022-CO002BD F8130022-C0003BD F8130022-CO004BD F8130022-C0005BD F8130022-CO006BD F8130022-Co007BD F8130022-Co008BD F8130022-CO009BD F8130022-CO01OBD F8130022-CO011 BD F8130022-Co012BD F8130022-GO013BD F8130022-CO014BD F8130022-Co015BD F8130022-Co016BD F8130022-CO017BD F8130022-Co01 8BD F8130022-CO019BD Mean:

Median:

Standard Deviation:

Range:

1369 1432 1250 1302 1452 1385 1810 1535 1416 1608 1603 1484 2526 1790 3994 1286 1650 1369 1499 1672 1484 630 1250-3994 Page 4 of 8 FSS Summary Report F8130022

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

F8130022C0001SM F8130022C0002SM F8130022C0003SM F8130022C0004SM F8130022C0005SM F8130022C0006SM F8130022C0007SM F8130022C0008SM F8130022C0009SM F8130022C0010SM F8130022C001 1 SM F8130022C0012SM F8130022C0013SM F8130022C0014SM F8130022C0015SM F8130022C0016SM F8130022C0017SM F8130022C0018SM F8130022C0019SM Mean:

Median:

Standard Deviation:

Ranqe:

7.42 16.39 88.18 18.96 20.24 18.96 125.36 57.41 29.21 6.14 20.24 7.42 4.86 4.86 7.42 4.86 6.14 21.52 7.42 24.9 16.39 32.06 4.86 to 125.36 Page 5 of 8 FSS Summary Report F8130022

Survey Unit Data Assessment:

The survey design required 19 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 F8130022

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

N/A Ambient Background Used (dpmIO0 cm2):

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

19 Median (dpm/100 cm2):

1484 Mean (dpm/100 cm2):

1672 Direct Measurement Standard Deviation 630 (dpm/100 cm2):

Total Standard Deviation (dpm/100 cm2):

630 Based on samples and backgrounds.

Maximum (dpm/100 cm 2):

3994 Material Type:

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

19 S+ Value:

19 Critical Value:

13 Sufficient Samples Collected:

Yes Maximum Value < DCGL:

Yes Median Value < DCGL:

Yes Mean. Value < DCGL:

Yes Maximum Value < DCGLemc:

Yes Class I 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 F8130022

Survey Unit Investigations and Results:

Three investigations (scan grids for penetrations 03, 06, & 08) were required for the scan measurements of the referenced penetrations 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 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.. Three potential areas of elevated activity were detected in penetrations within the survey unit. These areas were 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 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. 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 F8130022 meets the release criteria of 10CFR20.1402.

Page 8 of 8 FSS Summary Report F8130022 Maps November 5, 2008 Survey Unit F8130022

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  • Instrumentation November 5, 2008 Survey Unit F8130022

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 550 metal pipe - 3" 990 metal pipe - 3" M2350; 149789 43-68B; 161397 433 surface concrete 1033 surface concrete M2350; 142515 43-68B; 148453 257 surface metal 612 surface metal M2350; 142515 43-116-1B; 256007 796 surface concrete 3258 surface concrete 472 surface metal 1930 surface metal M2350; 149789 43-116-IB; 256006 491 juncture concrete 739 juncture concrete 730 metal pipe-2" 1320 metal pipe - 2" 2290 metal pipe - 3" 4160 metal pipe - 3" Tennelec; 0401171 N/A 6 dpm ar, 9 dpm P3 N/A Table 2-2. Investigation Criteria and DCGL Value Parameter d

aluc (d pm/100 cm2)

Investigation Criteria - Direct 162540 Investigation Criteria - Scan Variable' DCGLw 43000 DCGLEMC 162540 43-68B 43-68B 43-116B 43-116B 43-116B 43-98B 43-111B 43-111B surface concrete.

pipe-metal->14" pipe-concrete-4"- 14" pipe-metal-4"- 14" juncture concrete pipe-metal-3" pipe-metal-2" pipe-metal-3" 5840 cpm 9880 cpm 1990 cpm 3360 cpm 4260 cpm 3420 cpm 920 cpm 2900 cpm Page 2 of 2 Att. 2 Instrumentation F8130022 Investigation November 5, 2008 Survey Unit F8130022

Table 3-1 Survey Unit Investigation Grid Investigation Initial Value Investigatio Elevated Area Investigation DCGLemc dResult DCGLeno Result Unity Level (cpm)

(cpm)

(cpm)

Area (m2)

Factor (dpm/lOOcm2)

Fraction P03 3420 45203 45203 0.11 119.9 5156130 563727 0.109 P06 920 973 973 0.11 119.9 5156130 45868 0.009 P08 920 2123 2123 0.13 99 4252700 100076 0.024 DCGL =

SU Mean =

0039 Survey Unit Remainder 43,000 1672 EMC Unity Sum 0.181 Page 2 of 2 Att. 3 Investigation. F8130022 Data Assessment November 5, 2008 Survey Unit F8130022

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F8130022 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/100cm2 4,500 4,000 3,500 I

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