ML082620162

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Final Status Survey Summary Report, June 23, 2008, Pump Alley, Column 9.7 - 11.7, Walls Above One Meter - Ceilings, Survey Unit F8130451
ML082620162
Person / Time
Site: Rancho Seco
Issue date: 07/29/2008
From: Tallman D
Sacramento Municipal Utility District (SMUD)
To:
NRC/FSME
References
MPC&D 08-064 F8130451
Download: ML082620162 (28)
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Text

Rancho Seco Final Status Survey Summary Report June 23, 2008 Pump Alley, Column 9.7 - 11.7, Walls above one meter - ceilings Survey Unit F8130451 Prepared By: Dan A. Tallman A'

Date: June 24, 2008 FSS Engine r Reviewed By:.

sQ Ih j.%IA Date:

4-1-4 (00 Lead FSS Engineer Approved By.

Date:

7"l

  • o8 Dismantlemen(Su~perintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8130451, Pump Alley, Column 9.7 - 11.7, Walls above one meter - ceilings Survey Unit

Description:

Operating History: The Auxiliary Building is 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 -29' elevation showed a mean gross activity level of 544,756 dpm/100 cm2 and a maximum value of 11,370,000 dpm/100 cm. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the walls above one meter and ceiling of Pump Alley within 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 weredetermined using a random-start, fixed grid pattern and 247.3 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 9 FSS Summary Report F8130451

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 cm 2):

Design Sigma (dpm/100 cm 2):

Type I Error:

Type II Error:

Predominant Nuclide:

Sample Area (m2):

Scan Area (m 2):

Scan Coverage (%):

Zl-.

Sign P:

Calculated Relative Shift:

Relative Shift Used:

N-Value:

Design N-Value +20%:

Design Min Samples N:

Grid Spacing L:

0451 1

247.3 D.A.Tallman 43000 3.5 154086 21500 10204 0.05 0.05 Cs-137 6.87 247.3 100%

1.645 1.645 0.97725 2.1 2.1 12 15 36 2.6 Pump Alley, Column 9.7 - 11.7, Walls above one meter - ceilings Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class 1 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 9 FSS Summary Report F8130451

Survey Results:

A total of 39 direct measurements were made in F8130451. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. Several of the scan measurements indicated areas of elevated activity. ISOCS scan activity on the walls and ceiling ranged from 7158 to 83600 dpm/1OOcm 2 for Cs-137 and 1476 to 47670 dpm/100cm 2 for Co-60. 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.

Page 4 of 9 FSS Summary Report F8130451

Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/l00 cm F8130451-CO001BD F8130451-CO004BD F8130451 -CO005BD F8130451-CO006BD F8130451 -CO007BD F8130451-CO008BD F8130451-CO009BD F8130451-CO01OBD F8130451-COOIIBD F8130451-Co012BD F8130451-Co013BD F8130451-Co014BD F8130451-Co01 5BD F8130451-Co016BD F8130451-Co017BD F8130451-Co018BD F8130451-Co019BD F8130451 -CO02OBD F8130451-CO021BD F8130451-CO022BD F8130451-CO023BD F8130451-CO024BD F8130451 -Co025BD F8130451-CO026BD F8130451-CO027BD F8130451-CO028BD F8130451-CO029BD F8130451-CO03OBD F8130451 -C0031 BD F8130451 -Co032BD F8130451 -Co033BD F8130451-CO034BD F8130451-CO035BD F8130451 -Co036BD F8130451-CO037BD F8130451-CO038BD F8130451-CO039BD F8130451-CO04OBD F8130451-CO041BD Mean:

Median:

Standard Deviation:

Range:

7724 5063 2127 1836 3797 2625 2007 3740 2298 2044 3501 1675 3107 1821 1401 2583 1997 1956 3201 2288 1836 3206 2391 1982 3584 2625 2308 3704 3232 1904 5296 2744 2179 1805 1935 1701 1909 1618 1624 2676 2288 1234 1401 -7724, Page 5 of 9 FSS Summary Report F8130451

Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpml100 cm 2)

F8130451C0001SM F8130451CO004SM F8130451 COOO5SM F8130451 C0006SM F8130451 C0007SM F8130451 C0008SM F8130451 C0009SM F8130451CO010SM F8130451CO011SM F8130451CO012SM F8130451CO013SM F8130451CO014SM F8130451CO015SM F8130451CO016SM F8130451Co017SM F8130451Co018SM F8130451C0019SM F8130451 C0020SM F8130451CO021SM F8130451 C0022SM F8130451 C0023SM F8130451 C0024SM F8130451 C0025SM F8130451 C0026SM F8130451 C0027SM F8130451 C0028SM F8130451C0029SM F8130451CO030SM F8130451C0031SM F8130451C0032SM F8130451 C0033SM F8130451 C0034SM F8130451 C0035SM F8130451 C0036SM F8130451C0037SM F8130451 C0038SM F8130451 C0039SM F8130451 C0040SM F8130451C0041SM Mean:

Median:

Standard Deviation:

Range:

-2.24

-4.82

-2.24 4.22

-6.11

-0.95 1.64 5.51 1.64

-0.95

-3.53

-2.24

-0.95 4.22 10.68

-0.95 5.51 17.13

-4.82

-2.24

-2.24

-2.24

-2.24 5.51

-3.53

-4.82

-3.53 5.51 45.55 6.8 22.3 5.51 5.51

-3.53

-3.53

-2.24

-0.95

-0.95

-0.95 2.17

-0.95 9.29

-6.11 to 45.55 Page 6 of 9 FSS Summary Report F8130451

Survey Unit Data Assessment:

The survey design required 39 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 F8130451

Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm 2):

N/A Ambient Background Used (dpm/I00 cm2):

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

39 Median (dpm/100 cm 2):

2288 Mean (dpm/100 cm2):

2676 Direct Measurement Standard Deviation 1234 (dpm/100 cm 2):

Total Standard Deviation (dpm/100 cm 2):

1234 Based on samples and backgrounds.

Maximum (dpm/100 cm2):

7724 Material Type:

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

39 S+ Value:

39 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 F8130451

Survey Unit Investigations and Results:

Three (3) investigations (gamma scan grids 13, 16, & 46) 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.

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. 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 investigations required were performed and documented.

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 F8130451 meets the release criteria of 10CFR20.1402.

Page 9 of 9 FSS Summary Report F8130451 Maps June 23, 2008 Survey Unit F8130451

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F81 30451 -M5 SHEET 1 of 1 1 C HILL T C HILL Instrumentation June 23, 2008 Survey Unit F8130451

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; 149789 43-68B; 161397 433 1033 Tennelec; 0401171 N/A 6 dpm a, 12 dpm N/A SInstrument Detector MDC Model; Serial No.

Model; Serial No.-

(dpml00 cm2) 1510 (Co60)

ISOCS 1983920 1210 (Cs137) 3920_2m concrete geometry 12 m2 FOV Table 2-2. Investigation Criteria and DCGL Value ParameterVau (dpm/100 cm 2)

Investigation Criteria - Direct 154145 Investigation Criteria - Scan 154145 DCGLw 43000 DCGLEMC 154145 I

Value (d2.m/100 cmi)

To detect a I m hot spot at the EMC Criterion within the detector field of view 63,300 dpm/100 cm 2 Cs-137 21,275 dpm/100 cm 2 Co-60 3920_2mconcrete geometry 12 m2 FOV Page 2 of 2 Att. 2 Instrumentation F8130451 Investigation June 23, 2008 Survey Unit F8130451

Table 3-1 Survey Unit Investigation Investigation Initial Value Investigation Elevated Area Investigation DCGLemc Grid Level (dpm/nit cma )

Result Area DCGLemc Result Unity (dpm/lOOcm2)

(cpm)

(Mi2)

Factor (dpm/lOOcm2)

Fraction GS13 63,300 87,6003 44,6471 0.06 2404.6 103,374,580 231,596 0.002 GS16 63,300 69,3003 37,8221 0.14 94.8 4,074,680 196,193 0.050 GS46 63,300 69,5003 2,6522 NA NA NA 13,757 NA Comments:

1 One minute scaler count on 2350-1/43-68B 2 2350-1/43-68B scan in latching mode (maximum observed from four scan grids (BS01-BS04) established within the affected portion of GS46 FOV) 3 Total activity as calculated on F8130451 - Scan Sample Results worksheet (Co60/Cs137 summation)

Survey Unit Remainder Page 2 of 2 Att. 3 Investigation F8130451 Data Assessment June 23, 2008 Survey Unit F8130451

F81 30451 Gross Activity Sample Results Quantile Plot t'Qo DCGL = 43000 dpmll 00cm2 9,000 7,000.......

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E 9000

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