ML090980386

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Final Status Survey Summary Report Revision 1, May 1, 2008, Room 37 Lower Walls and Floor Survey Unit F8130481
ML090980386
Person / Time
Site: Rancho Seco
Issue date: 06/26/2008
From:
Sacramento Municipal Utility District (SMUD)
To:
NRC/FSME
Shared Package
ML090830613 List: ... further results
References
DPG 09-097
Download: ML090980386 (32)
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Text

Rancho Seco Final Status Survey Summary Report Revision I May 1, 2008 Room 37 Lower Walls and Floor Survey Unit F8130481 Prepared B Date:

F0 26 0 2'(Q FSS Engineer Reviewed By:- \\'**

Date: t ZV 'S Lead FSS Engineer Approved By:

Date:

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Dismantlement Suke-rintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8130481, Room 37 Lower Walls and Floor 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 and the 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 cm2 and a maximum value of 5,720,000 dpm/100 cm2. Direct measurements on the -29' elevation showed a mean gross activity level of 544,756 dpm/100 cm2 and a maximum value of 11,370,000 dpm/100 cm2. Direct measurements on the -20' elevation showed a mean gross activity level of 247,831 dpm/l00 cm2 and a maximum value of 10,080,000 dpm/100 cml. Direct measurements on the grade elevation showed a mean gross activity level of 373,758 dpm/100 cm2 and a maximum value of 5,800,000 dpm/1 00 cm 2. Direct measurements on the +20' elevation showed a mean gross activity, level of 85,408 dpm/l00 cm 2 and a maximum value of 1,900,000 dpm/100 cml. Direct measurements on the +40' elevation showed a mean gross activity level of 3,288 dpm/I00 cm 2 and a maximum value of 24,781 dpm/100 cm 2. 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 2,990 dpm/l 00 cm2. (The roof had been replaced prior to the classification survey.) Based on the classification procedure (DSIP-0020) and levels of gross activity reported, 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 I 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 236 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 F8130481

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

F813 Survey Unit:

Class:

SU Area (m2):

Evaluator:

DCGL (dpm/100 cm2):

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 (%):

ZIa :

ZI-P :

Sign P:

Calculated Relative Shift:

Relative Shift Used:

N-Value:

Design N-Value + 20%:

Design Min Samples N:

Grid Spacing L:

0481 1

236 Frank 43000 3.3 141900 21500 10204 0.05 0.05 Room 37 Lower Walls and Floor Structure Surface LTP Table 5-4 Gross Activity DCGL Class I Class I Default = 50% DCGL Cs-137 Co-60 used for Area Factor 6.94 236 100%

1.645 1.645 0.97725 2.1 2.1 12 15 34 2.6 and emc Class I Class I Uses 3.0 if Relative Shift is

>3 NUREG-1575 Table 5-5 Class 1 Class 1 L

L FSS Summary Report Page 3 of 9 F8130481

Survey Results:

A total of 40 direct measurements were made in F8130481. 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 3045 to 95059 dpm/100 cm2, based on a surveyor efficiency of 0.5 and no background subtracted. Scan grids 21 and 72 were above the investigation level which is based on 100 cm 2 and not the actual area of the probe which is 584cm2. The grids in question were rescanned with a 43-68B with the results for grid 21 at 8263 cpm and the results for grid 72 at 6058 cpm which are well below the investigation level of 19200 cpm. 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.

Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/100 cm F8130481-COOOIBD 1945 F8130481-C0002BD 2070 F8130481-CO003BD 2142 F8130481 -CO004BD 3865 F8130481-COOO5BD 2381 F8130481-CO006BD 4420 F8130481-CO007BD 2075 F8130481-CO008BD 2355 F8130481-CO009BD 4425 F8130481-CO0IOBD 2563 F8130481-CO011BD 2526 F8130481-CO012BD 2163 F8130481-CO013BD 2433 F8130481-CO014BD 2656 F8130481-Co01 5BD 4228 F8130481 -CO016BD 4155 F8130481-CO017BD 2749 F8130481-CO018BD 2308 F8130481-CO019BD 2588 F8130481-CO02OBD 2065 F8130481-CO021BD 2210 F8130481-Co022BD 1774 F8130481-CO023BD 2345 F8130481-CO024BD 2127 F8130481-CO025BD 1634 F8130481-CO026BD 1691 F8130481-CO027BD 1800 F8130481-CO028BD 1655 F8130481-CO029BD 1515 F8130481-CO03OBD 1556 F8130481-CO031BD 1655 Page 4 of 9 FSS Summary Report F8130481

Measurement ID Gross Activity (dpm/100 cm FBI 30481 -COO32BD 1520 F81 30481 -COO33BD 17 F8130481-CO034BD 10 F81 30481 -C0035BD 11 F8I130481 -CO036BD 13 FBI130481 -CO037BD 13 FBI 30481 -COO38BD 11 F81 30481 -CO039BD 27 F81 30481 -CO04OBD 13 Standard Deviation:82 1520 1478 1707 1515 1738 1738 1515 2573 1935 2295 2101 826 1478-4425 Ranqe:

1478 -4425 Page 5 of 9 FSS Summary Report F8130481

Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm2)

F8130481COOOISM F8130481 C0002SM F8130481 C0003SM F8130481 C0004SM F8130481 C0005SM F8130481 C0006SM F8130481CO007SM F8130481CO008SM F8130481 C0009SM F8130481CO010SM F8130481C0011SM F8130481CO012SM F8130481COO13SM F8130481CO014SM F8130481CO015SM F8130481CO016SM F8130481CO017SM

.F8130481Co018SM F8130481CO019SM F8130481CO020SM F8130481C0021SM F8130481CO022SM F8130481 C0023SM F8130481 C0024SM F8130481 C0025SM F8130481 C0026SM F8130481CO027SM F8130481CO028SM F8130481CO029SM F8130481 C0030SM F8130481C0031SM F8130481 C0032SM F8130481 C0033SM F8130481CO034SM F8130481 C0035SM F8130481C0036SM F8130481 C0037SM F8130481 C0038SM F8130481 C0039SM F8130481 C0040SM Mean:

Median:

Standard Deviation:

Range:

4.86 12.55 9.98 38.19 67.67 98.44 1.01 67.67 61.26

.7.42 81.77 7.42 2.29 63.82 35.62 6.14 12.55 9.98 9.98 15.11 3.58 3.58 20.24 9.98 9.98 11.27 22.8 7.42 17.68 38.19 13.83 9.98 11.27 18.96 9.98 16.39 4.86 16.39 18.96

-1.55 21.94 11.91 24.16

-1.55 to 98.44 FSS Summary, Report Page 6 of 9

.F.8130481

Survey Unit Data Assessment:

The survey design required 40 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 F8130481

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):

40 Median (dpm/100 cm 2):

2101 Mean (dpm/100 cm 2):

2295 Direct Measurement Standard Deviation 826 (dpm/I00 cm 2):

Total Standard Deviation (dpm/100 cm2):

826 Based on samples and backgrounds.

Maximum (dpm/100 cm2):

4425 Material Type:

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

40 S+ Value:

40 Critical Value:

25 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 F8130481

Survey Unit Investigations and Results:

One investigation (Grid 106) was required with results 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. One potential area of elevated activity was 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 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 investigation results while exceeding the DCGL are less than 5% of the DCGLCmC and pass unity.

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 F8130481 meets !the release criteria of 10CFR20.1402.

Page 9 of 9 FSS Summary Report F8130481 Revision 1 Maps May 1,2008 Survey Unit F8130481

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Revision 1 Instrumentation

  • May 1, 2008 Survey Unit F8130481

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

Model; Serial No.

(dpm/100 cm2 )

(dpm/100 cm2 )

M2350; 180733 43-98B; 148638 2520 Concrete 43-98B, 148638 M2350, 180733 Metal 820 1490 Metal 43-94; 148620 M2350; 180733 Conret 590 1030 Concrete 43-94, 148620 M2350, 180733 Metal 350 610 M2350; 203482 43-68B; 178510 433 1033 M2350; 142507 43-68B; 160781 433 1033 M2350; 142499 43-37; 148502 198 616 43-116-IB; 216071 796 5895 M2350; 193700 Conret 589 Concrete 43-116-1B, 216071 M2350, 193700 Metal 472 3492 Metal M2350, 203482 44-10, 211672 5.2 pCi/g Tennelec; 0401171 N/A 5 dpm a, 11 dpm 3 N/A Table 2-1, Survey Unit Instrumentation Detector MDC Instrument Serial No.

(dpm/100cm2)

I1 7830 Cs-137 InSpector 1000 1005457,9 3140 CO-60 Page 2 of 3 Att. 2 Instrumentation F8130481

Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2)

Investigation Criteria - Direct 141900 Investigation Criteria - Scan 141900 DCGLw 43000 DCGL[Mc 141900 Page 3 of 3 Att. 2 Instrumentation F8130481 Revision 1 Investigation May 1, 20,08 Survey Unit F8130481

Table 3-1 Survey Unit Investigation Investigation Initial Value Result Elevated Area ICvestigResult DUnity Grid/Location Level (cpm)

(cpm)

Result ADCGLemc Result Unity (cpm)

Area (

2)

Factor(dpmOOcm2)

Fraction

  • (1) Grid 106 36000 38266 N/A

.01 1290 5.55e7 1.35e5 0.0024 Survey Unit Remainder DCGL =

SU Mean =

0.0534 43,000 2295 EMC Unity Sum 0.0558 Gamma scans were performed to complete the particle survey and one elevated area were identified. The identified area was further bounded. and analyzed with InSpector 1000.

  • Locations on map attached to Download 08-220 The-results-are shownin Table 3-1 with results-less than unity.

Page 2 of 2 Att. 3 Investigation Data Assessment November 26, 2007 Survey Unit F8130481

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