ML082620081

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Final Status Survey Summary Report, June 20, 2008, Chemical Storage Room, Room 106, 0 AB, Survey Unit F8130862
ML082620081
Person / Time
Site: Rancho Seco
Issue date: 06/20/2008
From: Ellen Brown
Sacramento Municipal Utility District (SMUD)
To:
NRC/FSME
References
MPC&D 08-064
Download: ML082620081 (33)
v • d • e


Text

Rancho Seco Final Status Survey Summary Report June 20, 2008 Chemical Storage Room, Room #106, 0' AB Survey Unit F8130862 Prepared By: *UD §

-x_L

-Date: (G12 o 20 FSS Engineer Reviewed By:

D Date: L-O-e

[2 Lead FSS Engineer Approved By:

Date:_

Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8130862, Chemical Storage Room, Room #106, 0' AB 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 cm 2 and a maximum value of 5,720,000 dpm/1 00 cm2. 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/100 cm 2 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 cm2 and a maximum value of 5,800,000 dpm/100 cm 2. Direct measurements on the +20' elevation showed a mean gross activity level of 85,408 dpm/l100 cm 2 and a maximum value of 1,900,000 dpm/100 cm 2. Direct measurements on the +40' elevation showed a mean gross activity level of 3,288 dpm/1 00 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/l100 cm2 and a maximum value of 2,990 dpm/100 cm 2. (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 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 296.5 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 F8130862

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

F813 Survey Unit:

Class:

SU Area (m2):

Evaluator:

DCGL (dpmn100 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 (%):

Zl-a :

Sign P:

Calculated Relative Shift:

Relative Shift Used:

N-Value:

Design N-Value + 20%:

Design Min Samples N:

Grid Spacing L:

0862 1

296.5 Erin L. Brown 43000 3.5 150500 21500 6935 0.05 0.05 Cs-137 7.1 296.5 100%

1.645 1.645 0.99865 3.1 3

11 14 43 2.6 Chemical Storage Room, Room #106, 0 AB 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 F8130862

Survey Results:

A total of 43 direct measurements were made in F8130862. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. One of the scan measurements indicated elevated activity and required investigation as noted in Attachment 3. Scan activity ranged from 1834 to 487881 dpm/100 cm2, 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 F8130862-CO001BD 1333 F8130862-CO002BD 1525 F8130862-CO003BD 1463 F8130862-CO004BD 1484 F8130862-CO005BD 1816 F8130862-CO006BD.

4440 F8130862-CO007BD 2697 F8130862-CO008BD 1613 F8130862-CO009BD 1509 F8130862-COOIOBD 1551 F8130862-CO011BD 1821 F8130862-CO012BD 1276 F8130862-CO013BD 1152 F8130862-CO014BD 1037 F8130862-CO01 5BD 1063 F8130862-CO016BD 1209 F8130862-CO017BD 1167 F8130862-CO018BD 1152 F8130862-CO019BD 1240 F8130862-CO02OBD 1069 F8130862-CO021BD 1312 F8130862-CO022BD 1069 F8130862-CO023BD 1032 F8130862-CO024BD 1126 F8130862-CO025BD 1048 F8130862-CO026BD 1261 F8130862-CO027BD 1183 F8130862-CO028BD 1525 F8130862-CO029BD 1271 F8130862-CO03OBD 1333 F8130862-CO031BD 1520 F8130862-CO032BD 1375 F8130862-CO033BD 1520 F8130862-CO034BD 1395 F81 30862-CO035BD 1380 F8130862-CO036BD

.1525 Page 4 of 9 FSS Summary Report F8130862

F8130862-CO037BD 1375 F8130862-CO038BD 1541 F8130862-CO039BD 1307 F8130862-CO04OBD 1535 F8130862-C0041 BD 1162 F8130862-CO042BD 1219 F8130862ZC0043BD 674 Mean:

1426 Median:

1333 Standard Deviation:

561 Range:

674-4440 Page 5 of 9 FSS Summary Report F8130862

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

F8130862C0001SM F8130862C0002SM F8130862C0003SM F8130862C0004SM F8130862C0005SM F8130862C0006SM F8130862C0007SM F8130862C0008SM F8130862C0009SM F8130862C0010SM F8130862C0011SM F8130862C0012SM F8130862C0013SM F8130862C0014SM F8130862C0015SM F8130862C0016SM F8130862C0017SM F8130862C0018SM F8130862C0019SM F8130862C0020SM F8130862C0021SM F8130862C0022SM F8130862C0023SM F8130862C0024SM F8130862C0025SM FB130862C0026SM F8130862C0027SM F8130862C0028SM F8130862C0029SM F8130862C0030SM F8130862C0031SM F8130862C0032SM F8130862C0033SM F8130862C0034SM F8130862C0035SM F8130862C0036SM F8130862C0037SM F8130862C0038SM F8130862C0039SM F8130862C0040SM F8130862C0041 SM F8130862C0042SM F8130862C0043SM Mean:

Median:

Standard Deviation:

Range:

4.22

-2.24

-2.24 0.34

-2.24

-0.95

-3.53 0.34

-3.53

-2.24

-0.95

-0.95

-2.24

-4.82

-2.24

-4.82

-2.24

-4.82 2.93

-4.82

-3.53

-3.53

-3.53

-0.95

-0.95

-4.82

-4.82

-2.24

-3.53

-2.24,

-4.82

-3.53

-2.24

-2.24

-3.53

-4.82

-0.95

-2.24

-3.53 1.64

-2.24 6.8

-0.95

-2.12

-2.24 2.5

-4.82 to 6.8 Page 6 of 9 FSS Summary Report F8130862

Survey Unit Data Assessment:

The survey design required 43 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 F8130862

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

N/A Ambient Background Used (dpm/100 cm2):

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

43 Median (dpm/100 cm 2):

1333 Mean (dpm/100 cm2):

1426 Direct Measurement Standard Deviation 561 (dpm/100 cm 2):

Total Standard Deviation (dpm/100 cm 2):

561 Based on samples and backgrounds.

Maximum (dpm/100 cm2):

4440 Material Type:

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

43 S+ Value:

43 Critical Value:

.27 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 F8130862

Survey Unit Investigations and Results:

An investigation was required for one scan measurement as indicated in Attachment 3.

Investigation of the area resulted in the decision to perform additional remediation. The investigation result in attachment 3 represent the residual radioactivity levels achieved after additional remediation.

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 I 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 as indicated in Attachment 3.

==

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 cm2 and none.of the removable surface activity measurements exceeded 10% of the DCGL. An investigation was required for one scan measurement as indicated in Attachment 3.

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 F8130862 meets the release criteria of 10CFR20.1402.

Page 9 of 9 FSS Summary Report F8130862 Maps June 20, 2008 Survey Unit F8130862

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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; 142514 43-98B; 148639 N/A 1680 M2350; 180733 43-94; 148620 N/A 1030 M2350; 203486 43-68B; 190476 433 1033 M2350; 193700 43-68B; 190294 433 1033 M2350; 149789 43-68B; 161397 433 1033 M2350; 203486 43-116-1B; 190173 N/A 3258 M2350; 142514 43-11 lB; 148642 N/A 7020 M2350; 180733 43-111B; 148641 N/A 1120 Tennelec; 0401171 N/A 5.9 dpm ct, N/A 11.7 dpmr The MDC noted for the detector model 43-98B, serial # 148639 and detector model 43-111B, 'serial # 148642 is for the three inch diameter piping which is the most conservative.

Table 2-2. Investigation Criteria and DCGL Value Parameter dp lue cm2)

(dpmll00 c2 Investigation Criteria - Direct 150500 Investigation Criteria - Scan 150500 DCGLW 43000 DCGLEMC 150500 Page 2 of 2 Att. 2 Instrumentation F8130862 Investigation June 20, 2008 Survey Unit F8130862 0

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

(cpm)

(cpm)

Area (m2)

Factor (dpm/lOOcm2)

Fraction C0040BS 20,440 66,506 2,108 N/A N/A 150,500 15,464 0

Survey Unit Remainder DCGL43,000 SU26Mean=

0.03 EMC Unity Sum 0.03 The grid above was initially greater than DCGLemc. Investigation of the area resulted in the decision to perform additional remediation. The investigation result above represents the residual radioactivity level after additional' remediation.

Page 12 of 2 Att. 3 Investigation F8130862 Data Assessment June 20, 2008 Survey Unit F8130862

CF81 30862 Gross Activity Sample Results Quantile Plot DCGL 43000 dpm/1O00cm 2 4,000 43,000 K 2,0 0 0 1n

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