ML082620118

East DHR Pump Room (Lowers), Survey Unit F8130031

ML082620118
Person / Time
Site:	Rancho Seco (DPR-054)
Issue date:	06/16/2008
From:	Tallman D Sacramento Municipal Utility District (SMUD)
To:	NRC/FSME
References
MPC&D 08-064
Download: ML082620118 (12)

Text

Rancho Seco Final Status Survey Summary Report (Rev. 1)

June 16, 2008 East DHR Pump Room (lowers)

Survey Unit F8130031 Prepared By: Dan A. Tallman,'04ZN-aDate:

June 16, 2008 T

FSS Engineer Reviewed By:

Date: -7,1 -5 (

Lead FSS Engineer Approved By:

7 Date:

Dismantlem St; Su ointendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8130031, East DHR Pump Room (lowers)

Survey Unit

Description:

Operating History: The Auxiliary Building, a 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 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. 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/100 cm2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the lower walls and floor of the East Decay Heat Pump Room of the auxiliary building was determined to be a Class 1 survey unit.

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 165.3 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 F8130031

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

F813 Survey Unit:

Class:

SU Area (ml):

Evaluator:

DCGL (dpm/100 cm 2):

Area Factor:

Design DCGLemc (dpm/100 cm2):

LBGR (dpmi/100 cm2):

Design Sigma (dpm/100 cm2):

Type I Error:

Type II Error:

Predominant Nuclide:

Sample Area (m):

Scan Area (M2):

Scan Coverage (%):

Z1-, :

ZJ-P :

Sign P:

Calculated Relative Shift:

Relative Shift Used:

N-Value:

Design N-Value + 20%:

Design Min Samples N:

Grid Spacing L:

0031 1

165 D.A.Tallman 43000 3.54 152220 21500 9976 0.05 0.05 Cs-137 7

165.3 100%

1.645 1.645 0.97725 2.1 2.1 12 15 24 2.6 East DHR Pump Room (lowers)

Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class I Default = 50% DCGL Class 1 Class I Uses 3.0 if Relative Shift is

>3 NUREG-1575 Table 5-5 Class 1 Class 1 Page 3 of 8 FSS Summary Report F8130031

Survey Results:

A total of 30 direct measurements were made in F813003 1. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. Multiple scan measurements indicated areas of elevated activity. Scan activity ranged from 3216 to 1015490 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 F8130031-COOOIBD F8130031 -C0002BD F8130031-CO003BD F8130031-CO004BD F8130031 -CO005BD F8130031-C0006BD F8130031-CO007BD F8130031 -CO008BD F8130031-CO009BD F8130031-CO01OBD F8130031-CO01 IBD F8130031-Co012BD F8130031-CO013BD F8130031-Co014BD F8130031-Co015BD F8130031-CO016BD F8130031-Co017BD F8130031-CO018BD F8130031-CO019BD F8130031 -CO02OBD F8130031-C0021BD F8130031-C0022BD F8130031-CO023BD F8130031-CO024BD F8130031-C0025BD F8130031 -CO026BD F8130031-C0027BD F8130031-CO028BD F8130031-CO029BD F8130031-CO03OBD Mean:

Median:

Standard Deviation:

Ranqe:

2137 2682 2054 10738 2137 2080 1758 1587 1764 1733 1899 1867 2215 1924 1509 1489 1395 1489 2044 1717 1810 2931 1364 1452 1463 1411 1338 1432 1344 1613 2079 1746 1681 1338-10738 Page 4 of 8 FSS Summary Report F8130031

Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpml100 cm2)

F8130031CO001SM F8130031CO002SM F8130031 C0003SM F8130031 C0004SM F8130031COOO5SM F8130031 C0006SM F8130031 C0007SM F8130031 C0008SM F8130031CO009SM F8130031Co010SM F8130031Co01iSM F8130031Co012SM F8130031Co013SM F8130031C0014SM F8130031Co015SM F8130031Co016SM F8130031Co017SM F8130031Co018SM F8130031Co019SM F8130031 C0020SM F8130031C0021SM F8130031 C0022SM F8130031C0023SM F8130031 C0024SM F8130031 C0025SM F8130031 C0026SM F8130031 C0027SM F8130031 C0028SM F8130031 C0029SM F8130031CO030SM Mean:

Median:

Standard Deviation:

Range:

12.55 6.14 12.55 34.34 8.7 9.98 9.98 6.14 2.29 9.98 9.98

-0.27 9.98 4.86 3.58

-1.55

-1.55 1.01 1.01 3.58 2.29 7.42 1.01 1.01 3.58 3.58 2.29 1.01 2.29 2.29 5.67 3.58 6.81

-1.55 to 34.34 Page 5 of 8 FSS Summary Report F8130031

Survey Unit Data Assessment:

The survey design required 30 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 F8130031

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):

30 Median (dpm/100 cm2):

1746 Mean (dpm/100 cm 2):

2079 Direct Measurement Standard Deviation 1681 (dpm/100 cm 2):

Total Standard Deviation (dpm/100 cm 2):

1681 Based on samples and backgrounds.

Maximum (dpm/100 cm 2):

10738 Material Type:

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

30 S+ Value:

30 Critical Value:

20 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 F8130031

Survey Unit Investigations and Results:

Twenty-Four (24) investigations 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.

During routine surveillance surveys utilizing the 44-10 Nal detector, discovery was made in grids 16, 29, and 32. The results of this discovery are detailed in Revision 1 to. The EMC unity rule was not exceeded as shown in Revision 1 to 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. Potential areas of elevated activity were detected and evaluated as shown in Attachment 3 demonstrating 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 investigations required were performed and evaluated as shown in Attachment 3 demonstrating the EMC criterion was met.

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 F8130031 meets the release criteria of 10CFR20.1402.

Page 8 of 8 FSS Summary Report F8130031 (Rev. 1)

Instrumentation June 16, 2008 Survey Unit F8130031

Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No.

Model; Serial No.

(dpm/100 cm 2)

(dpm/1 00

____cm 2 )

M2350; 142514 43-98B; 148639 1400 2520 M2350; 149794 43-68/5B; 149103 433 1033 M2350; 142507 43-116-IB; 256008 4911 7391 M2350; 142507 43-116-1B; 256008 796 3258 M2350; 149794 43-116-1B; 256005 4911 7391 M2350; 149794 43-116-1B; 256005 796 3258 M2350; 203482 44-10; 211672 NA 18720 M2350; 203486 44-10; 171995 Tennelec; 0401171 N/A 5.15 dpm o, 8.12 dpmf3 N/A 43-116-lB - Juncture Scan - concrete Table 2-2. Investigation Criteria and DCGL Value Parameter d

aluc (dpm/1 00 CM2)

Investigation Criteria - Direct 152220 Investigation Criteria - Scan 430001 DCGLw 43000 DCGLEMC 152220 Scan Investigation Level set at DCGLw 2 Scan Investigation Level for routine 44-10 surveillance scan set at 20,000 cpm Page 2 of 2 Att. 2 Instrumentation F8130031 (Rev. 1)

Investigation June 16, 2008 Survey Unit F8130031

Table 3-1 Survey Unit Investigation Grid Investigation Level (cpm)

Initial Value (cpm)

Investigation Result Elevated Area (m2)

Area Factor DCGLemc Investigation Result (dpm/l OOcm2)

DCGLemc Unity Fraction G08 5840 9367 Gil 19902 2648 G12 19902 2373 G17 5840 8419 G22 19902 46997 G23 5840 12425 G28 19902 3651 G29 5840 13611 G30 5840 6740 G31 19902 2334 G32 5840 44119 G33 19902 2010 G53 5840 66837 G54 5840 7299 G55 5840 27465 G68 5840 7908 G119 5840 9470 J08 19902 3154 J09 19902 2987 J18 19902 4663 J19 19902 3312 J33 19902 3808 J34 19902 4605 G16GS 20000 39000 0.08 158 6796583 49450 0.007 0.75 194 833692 57217 0.066 0.99 15 646621 51275 0.076 N/A N/A N/A

<DCGL 0.000 N/A N/A N/A

<DCGL 0.000 0.059 206 8848359 71724 0.008 0.99 15 646621 78889 0.119 0.09 135 5823227 74722 0.012 N/A N/A N/A

<DCGL 0.000 0.75 19.4 833692 50297 0.058 N/A N/A N/A

<DCGL 0.000 0.99 15 646621 43431 0.064 N/A N/A N/A

<DCGL 0.000 N/A N/A N/A

<DCGL 0.000 N/A N/A N/A

<DCGL 0.000 N/A N/A N/A

<DCGL 0.000 0.062 196 8424066 88650 0.010 N/A N/A N/A

<DCGL 0.000 N/A N/A N/A

<DCGL 0.000 N/A N/A N/A

<DCGL 0.000 N/A N/A N/A

<DCGL 0.000 0.044 275 11832787 50886 0.004 0.052 233 10027797 106393 0.010 0.0316 411.85 17709550 1,513,739 0.085 G29GS 20000 36000 36000 0.0323 403 17329000 1,397,297 0.081 G32GS 20000 74000 74000

[ 0.0323 403 17329000 2,872,222 0.166 During routine surveillance surveys using the 44-10 (NaI), discovery was made within grids 16, 29, & 32.

Survey Unit Remainder DCGL = 43,000 SU Mean = 2080 0.048 EMC Unity Sum 0.852 I Scaler measurement, Page 2 of 2 2 Revised from 1100 ccpm @ 0.42 scan rate coefficient, 3 Remediated and resurveyed Att. 3 Investigation F8130031