ML082620259

Final Status Survey Summary Report, June 13, 2008, AB -20' E-W Corridor, Column N-R, Survey Unit F8130151

ML082620259
Person / Time
Site:	Rancho Seco
Issue date:	07/29/2008
From:	Sacramento Municipal Utility District (SMUD)
To:	NRC/FSME
References
MPC&D 08-064 F8130151
Download: ML082620259 (28)

Text

Rancho Seco Final Status Survey Summary Report June 13, 2008 AB -20' E-W corridor, column N-R Survey Unit F8130151 Prepared By: Dan A. Tallman Date: June 13, 2008 FSS Engineer Reviewed By:, ,; Date: 3/1 1 - -,

Lead FSS Engineer Approved By: $7 Date:________

Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8130151, AB -20' E-W corridor, column N-R 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. The 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/1 00 cm. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, Survey Unit 813015 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 were determined using a random-start, fixed grid pattern and 238 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 F8130151

Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F813 AB -20' E-W corridor, column N-R Survey Unit: 0151 Structure Surface Class: 1 LTP Table 5-4 SU Area (m2): 238 Evaluator: D.A.Tallman DCGL (dpm/100 cm 2): 43000 Gross Activity DCGL Area Factor: 3.5 Class 1 Design DCGLemc 152357 Class 1 (dpm/100 cm2):

LBGR (dpm/100 cm 2): 21500 Default = 50% DCGL I Design Sigma (dpm/100 cm ):2 12035 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): 7 Class 1 Scan Area (M2): 238 Scan Coverage (%): 100% Class 1 1.645 1.645 Sign P: 0.955435 Calculated Relative Shift: 1.7 Relative Shift Used: 1.7 Uses 3.0 if Relative Shift is

>3 N-Value: 14 Design N-Value + 20%: 17 NUREG-1575 Table 5-5 Design Min Samples N: 34 Class 1 Grid Spacing L: I 2.6 Class 1 Page 3 of 9 FSS Summary Report F8130151

Survey Results:

A total of 43 direct measurements were made in F 8130151. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. No FSS measurements indicated areas of elevated activity.

Scan activity ranged from 2389 to 141693 dpm/100 cm 2, basedon a surveyor efficiency of 0.5 and no background subtracted. ISOCS scan activity on the walls and ceiling ranged from 1736 to 7034 dpm/1OOcm 2 from Cs-137 with all scans MDA 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 F8130151

Table 2. Direct Measurement Results Measurement ID Gross Activity (dpmllO0 cm F8130151-CO001BD 1530 F8130151 -C0002BD 1395 F8130151-CO003BD 1821 F8130151-CO004BD 2692 F8130151-CO005BD 1572 F81301.51-CO006BD 9104 F8130151-CO007BD 2028 F8130151-CO008BD 2526 F8130151 -CO009BD 1271 F8130151-COOIOBD 3512 F8130151-CO011BD 2490 F8130151-CO012BD 4617 F8130151-CO013BD 1110 F8130151-CO014BD 1219 F8130151-CO015BD 2111 F8130151-CO016BD 1344 F8130151-CO017BD 1318 F8130151-CO018BD 1426 F8130151-CO019BD 1281 F8130151-CO02OBD 1401 F8130151 -CO021 BD 1172 F8130151 -CO022BD 1079 F8130151 -CO023BD 1271 F8130151-CO024BD 1255 F8130151-CO025BD 1266 F8130151-CO026BD 1120 F8130151-CO027BD 1224 F8130151-CO028BD 1255 F8130151-CO029BD 1120 F8130151-CO03OBD 1323 F8130151 -CO031BD 1323 F8130151 -CO032BD 1183 F8130151-CO033BD 1255 F8130151-CO034BD 1157 F8130151-CO035BD 1354 F8130151-CO036BD 1323 F8130151-CO037BD 1458 F8130151-CO038BD 1478 F8130151-CO039BD 814 F8130151 -CO04OBD 1286 F8130151-CO041BD 1297 F8130151-CO042BD 1395 F8130151-CO043BD 1375 Mean: 1734 Median: 1323 Standard Deviation: 1343 Range: 814-9104 Page 5 of 9 FSS Summary Report F8130151

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

F8130151COOOISM 39.09 F8130151CO002SM 19.72 F8130151 C0003SM 14.55 F8130151 CO004SM 73.96 F8130151C0005SM 23.59 F8130151CO006SM 77.83 F8130151CO007SM 53.29 F8130151 C0008SM 115.28 F8130151 CO009SM 39.09 F8130151CO010SM 55.88 F8130151CO01ISM 42.96 F8130151CO012SM 30.05 F8130151Co013SM 4.22 F8130151C0014SM 5.51 F8130151Co015SM 98.49 F8130151 CO016SM 6.8 F8130151 CO017SM 2.93 F8130151CO018SM 10.68 F8130151CO019SM 4.22 F8130151 C0020SM 0.34 F8130151CO021SM -0.95 F8130151 C0022SM 10.68 F8130151 C0023SM 8.09 F8130151 C0024SM -0.95 F8130151 CO025SM 2.93 F8130151 C0026SM 8.09 F8130151 C0027SM 2.93 F8130151 C0028SM 27.46 F8130151 CO029SM 1.64 F8130151 CO030SM 30.05 F8130151 CO031SM 4.22 F8130151 CO032SM 2.93 F8130151 C0033SM 1.64 F8130151 C0034SM 8.09 F8130151 C0035SM -0.95 F8130151 C0036SM -3.53 F8130151 C0037SM -4.82 F8130151 C0038SM -0.95 F8130151 C0039SM -3.53 F8130151CO040SM -3.53 F8130151 C0041 SM - -2.24 F8130151CO042SM -4.82 F8130151 C0043SM -2.24 Mean: 18.57 Median: 5.51 Standard Deviation: 28.85 Range: -4.82 to 115.28 Page 6 of 9 FSS Summary Report F8130151

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 F8130151

Table 4. Data Assessment Results Survey Results Parameter Value Comment 2

Material Background Used (dpm/100 cm ): N/A Ambient Background Used (dpm/100 cm2): N/A Average Ambient BKG = 0 Actual Direct Measurements (N): 43 Median (dpm/100 cm 2 ): 1323 2

Mean (dpm/100 cm ): 1734 Direct Measurement Standard Deviation 1343 2

(dpm/100 cm ):

Total Standard Deviation (dpm/100 cm 2): 1343 Based on samples and backgrounds.

Maximum (dpm/100 cm 2): 9104 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 F8130151

Survey Unit Investigations and Results:

No investigations were required based on the results of the FSS performed within this survey unit.

During routine surveillance surveys utilizing the 44-10 Na! detector, discovery was made in grids 55/56. The results of this discovery are detailed in attachment 3. The EMC unity rule was not exceeded as shown in 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. 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 576 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 reported demonstrating compliance with the acceptance criteria..

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 F8130151 meets the release criteria of 10CFR20.1402.

Page 9 of 9 FSS Summary Report F8130151

Attachment 1 Maps June 1-3, 2008 Survey Unit F8130151

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• SMUn SURFACE AREA ESTIMATE SACRAMENTO MUNICIPAL Total - 238.0 m2 0 1 2 345 UTILITY. DISTRICT F8130151-M1 4E R13000nl*e S 1 1` TCHILL F

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00 8"= 1,00" uj AUXILIARY BUILDING EL. -20 ROOM 15 Scale Meters BETWEEN COLS. "N" & "R" 0 1 2 3 osmu* SACRAMENTO MUNICIPAL GAMMA SCAN MEASUREMENT LOCATIONS UTILITY DISTRICT F81 30151 -M3 F:'.E 8130O.02 SHT I OF 3 T C HILL-F~E 81300.02e SI-fr 1 OF 3

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Attachment 2 Instrumentation June 13, 2008 Survey Unit F8130151

Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No. Model; Serial No. (dpm/100 cm2 ) (dpmll00 cm 2 )

350A 630 A 585 0 990B M2350; 142514 43-98B; 148639 1400 D 2520 D M2350; 203481 43-6813; o1033 161405

~VJtk 4313E 433 E M2350; 149789 43-68B; 161397 796

• 3258 E M2350; 149789 43-116-1B; 256006 491' 491' 3

____7399F __F M2350; 203482 44-10; 211672 NA 18720 Tennelec; 0401171 N/A 6 dpm x, 12 dpm 3 N/A APenetration - 2" - metal B Penetration - 3" - metal c Penetration - 4" - metal DPenetration - 4" - concrete E Surface scan - concrete F Juncture scan - concrete Detector MDC Instrument Model; Serial No. Model; Serial No. (dpm/100 cm2 )

1040 (Co60)

ISOCS 1983920 1540 (Cs 137) 3920_2m concrete geometry 12.5 m2 FOV Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2)

Investigation Criteria - Direct 21500 Investigation Criteria - Scan 43000' DCGLw 43000 DCGLEMc N/A

'Scan Investigation Level for routine 44-10 surveillance scan set at 20,000 cpm (- 60% DCGLEMC 0.75 M2 )

Value (dpmll00 cm 2 )

Instrument Parameter To detect a I m hot spot at the EMC Criterion within the detector field of view Investigation Criteria - 63,300 dpm/100 cm 2 Cs-137 ISOCS Concrete Scan 1',2 21,275 dpm/100 cm' Co-60 3920_2m concrete geometry -12.5 m' FOV 2 Investigation Level set to 43,000 dpm/1OOcm 2 Cs-137, ND Co-60 for investigation survey instructions.

Page 2 of 2 Att. 2 Instrumentation F8130151

Attachment 3 Investigation June 13, 2008 Survey Unit F8130151

Table 3-1 Survey Unit Investigation Grid Investigation Initial Value Iniia Value InRest Result Elevated Aeiaon Area ar DCGLemc Investigation Result DCGLemc Invel i Unity Level (cpm) (cpm) (cpm) Area (m2) Factor (dpm/lOOcm2 Fraction C55/56GS' 20000 32000 <20000 0.23 58.36 2509480 776,276 0.309 C55/56GS 2 20000 29000 <20000 NA NA NA NA NA C55/56GS 3 5840 NA 2693 NA NA NA 19756 NA C55/56GS 3 19904 NA 911 NA NA NA 20723 NA Comments:

1 Discovery made during routine surveillance with 44-10. Insufficient survey documentation available to distinguish exact FSS grid identification. FSS grids corresponding to surveillance location are 55/56 (including the adjacent juncture) as indicated. Total area of impact conservatively estimated at - 0.25m 2. General location resides in the western portion of the grid(s) as noted on survey documentation.

2 Discovery made during routine surveillance with 44-10. Insufficient survey documentation available to distinguish exact FSS grid identification. FSS grids corresponding to surveillance location are 55/56 (including the adjacent juncture) as indicated. Total area of impact conservatively estimated at - 0.25m 2. General location resides in the eastern portion of the grid(s) as noted on survey documentation.

3 Post remediation verification survey included beta scan survey measurements of grid and accompanying juncture area; 4 Juncture remediation resulted in a geometry most accurately conforming to that of the Cs137 surface scan selected in the DQA.

Survey Unit Remainder DCGL = SU Mean = 0.04 43,000 1733 EMC Unity Sum 0.357 Page 2 of 3 Att. 3 Investigation F8130151

Page 3 of 3 Att. 3 Investigation F8130151 Attachment 4 Data Assessment June 13, 2008 Survey Unit F8130151

CF81 30151 Gross Activity Sample Results Quantile Plot 0 DCGL = 43000 dpm/100cm2 10,000 9,000 -

6,000 5,000.-,  :

CD 3,000 13: 4,0002

.-

2,000.~

---

1323 1,000J 0

0 20 40 60 80 100 Percentile

-t

• Direct Measurements (dpm/100cm2) - median - - -75th Percentile 50th Percentile

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F8130151 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmll00cm' 10000 p 0

8000 C4J E

8000 1 5792 0

4000 00 2000 00 0 0_0_

1734 0 00 000000000000oOQO0O(00 0 000 0

-2000 i~ j  : LI1 J1 .1I 1

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-4000 C)j 00000000 00 BS00000000000 0 Measurement Locations o Gross Activity - Average - - "+3StDev .... -3StDev"

F8130151 Gross Activity Frequency Plot DCGL = 43000 dpmiI 00cm2 44 42 CD2 36 34 0

LL 24 22 10 00 20 R

10 8

6 4

2 0

It It 0r 0 uJI Bins - Upper End Value (dpm/100cm2)