ML090980389

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Final Status Survey Summary Report Revision 1, May 1, 2008 Room 41 Lower Walls and Floor Survey Unit F8130561
ML090980389
Person / Time
Site: Rancho Seco
Issue date: 05/01/2008
From:
Sacramento Municipal Utility District (SMUD)
To:
NRC/FSME
Shared Package
ML090830613 List: ... further results
References
DPG 09-097
Download: ML090980389 (30)
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Rancho Seco Final Status Survey Summary Report Revision I May 1, 2008 Room 41 Lower Walls and Floor Survey Unit F8130561 Prepared By. P * - Date: J Jd FSS Engineer Revi ewed B Date:

Lead FSS Engineer Approved By:. Date:

Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8130561, Room 41 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 cm 2 and a maximum value of 5,720,000 dpm/100 cm 2 . 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/100 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/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 236 m 2 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 F8130561

Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter, Survey Area: F813 Room 41 Lower Walls and Floor Survey Unit: 0561 Structure Surface Class: 1 LTP Table 5-4 SU Area (m2): 236 Evaluator: Frank DCGL (dpm/100 cm 2 ): 43000 Gross Activity DCGL Area Factor: 3.3 Class 1 Design DCGLemc 141900 Class 1 (dpm/100 cm 2):

LBGR (dpm/100 cm 2): 21500 Default = 50% DCGL Design Sigma (dpm/100 cm2 ): 10204 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Co-60 used to determine area factor/emc Sample Area (m): 6.94 Class 1 2

Scan Area (M ): 236 Scan Coverage (%): 100% Class 1 1.645 Zip:

1.645 Sign P: 0.97725 Calculated Relative Shift: 2.1 Relative Shift Used: 2.1 Uses 3.0 if Relative Shift is

>3 N-Value: 12 Design N-Value + 20%: 15 NUREG-1575 Table 5-5 Design Min Samples N: 34 Class 1 Grid Spacing L: 2.6 Class 1 Page 3 of 9 FSS Summary Report F8130561

Survey Results:

A total of 40 direct measurements were made in F8130561. 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 areas of elevated activity. Scan activity ranged from 2006 to 59501 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 F8130561-C0001BD 3538 F8130561-CO002BD 2526 F8130561-CO003BD 3112 F8130561-C0004BD 2848 F8130561-C0005BD 2142 F8130561-CO006BD 2495 F8130561-CO007BD 2438 F8130561-C0008BD 2500 F8130561 -CO009BD 6282 F8130561-Co01OBD 5530 F8130561-CO011BD 2339 F8130561-C0012BD 2298 F8130561-CO013BD 11884 F8130561-C0014BD 2630 F8130561-CO015BD 2090 F8130561-CO016BD 3455 F8130561-CO017BD 2267 F8130561-CO018BD 2397 F8130561-C0O019BD 4098 F8130561-C0020BD 3315 F8130561-CO021BD 2179 F8130561-CO022BD 1764 F8130561-C0023BD 1883 F8130561-CO024BD 4020 F8130561-C0025BD 1696 F8130561-CO026BD 1535 F8130561-CO027BD 1525 F8130561-CO028BD 1675 F8130561-C0029BD 1509 F8130561-CO03OBD 1577 F8130561-CO031BD 1541 F8130561-CO032BD 1790 F8130561-CO033BD 1862 F8130561-CO034BD 1909 F8130561-CO035BD 1644 F8130561-CO036BD 1769 Page v

4 of 9 FSS Summary Report F813056 I

Measurement ID Gross Activit (dpm/100 cm F8130561-CO037BD 1738 F8130561-CO038BD 1323 F8130561-CO039BD 1468 F8130561-C0040BD 1240 Mean: 2646 Median: 2160 Standard Deviation: 1849 Range: 1240 - 11884 Page 5 of 9 FSS Summary Report F8130561

Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpmll00 cm2 )

F8130561C0001SM 117.66 F8130561 C0002SM 88.18 F8130561 C0003SM 18.96 F8130561CO004SM 81.77 F8130561 COO0SSM 80.49 F8130561 C0006SM 15.11 F8130561 C0007SM 70.23 F8130561 C0008SM 70.23 F8130561 C0009SM 77.93 F8130561Co010SM 95.87 F8130561 C001o1 SM 68.95 F8130561CO012SM 43.31 F8130561C0013SM 108.69 F8130561CO014SM 47.16 F8130561CO015SM 30.49 F8130561C0016SM 97.15 F8130561Co017SM 49.72 F8130561CO018SM 20.24 F8130561C0019SM 70.23 F8130561 C0020SM 53.57 F8130561 C0021 SM 15.11 F8130561CO022SM 9.98 F8130561 C0023SM 1.01 F8130561 C0024SM 12.55 F8130561 C0025SM 1.01 F8130561 C0026SM 4.86 F8130561 C0027SM 3.58 F8130561CO028SM 3.58 F8130561 C0029SM 2.29 F8130561CO030SM 4.86 F8130561C0031SM 3.58 F8130561 C0032SM 2.29 F8130561 C0033SM 18.96 F8130561C0034SM 4.86 F8130561 C0035SM 3.58 F8130561 C0036SM 11.27 F8130561CO037SM 11.27 F8130561 C0038SM 2.29 F8130561 C0039SM 3.58 F8130561 C0040SM 3.58 Mean: 35.75 Median: 17.03 Standard Deviation: 36.64 Range: 1.01 to 117.66 Page 6 of 9 FSS Summary Report F8130561

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 F8130561

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 ): 2160

" Mean (dpm/100 cm 2): 2646 Direct Measurement Standard Deviation 1849 (dpm/100 cm 2):

Total Standard Deviation (dpm/100 cm 2): 1849 Based on samples and backgrounds.

Maximum (dpm/100 cm 2 ): 11884 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 F8130561

Survey Unit Investigations and Results:

One investigation (Grid 89) is required as a result of particle scans performed with NaI detector 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. 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%/o of the DCGL. Investigations results while exceeding the DCGL are less than 5% DCGLmc 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 F8130561 meets the release criteria of IOCFR20.1402.

Page 9 of 9 FSS Summary Report F8130561

Attachment 1 Revision I Maps May 1, 2008 Survey Unit F8130561

Random Starting Point is 0.048m from the north wall and 2.18 m from the west wall - 01BD

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TRENCH I

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FLOOR PLAN I Direct Beta locations areI2.6m from the random start point EL. -17*-1)' 4 "

/ 2 ,117 m g2BID 2Mr 33BD 2:6 m ..34BD 2.6m 35 BD32.6 m .3613D -2.6 m37BD 38BD.

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ELEVATION LOOKING WEST ELEVATION LOOKING EAST AUXILIARY BUILDING EL. - 29' ROOM 41 FLOOR & LOWER WALLS BETA DIRECT RANDOM START LOCATION SACRAMENTO MUNICIPAL A'

UTtLITY DISTRICT F8130561 -M1 7'-E: 81300-02q RIC RAY1,,.ON *,

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0 Room 41 Floor and Trench Scans V

118 SQ M CONCRETE KEY PLANS N

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A FLOOR PLAN AUXILIARY BUILDING EL. -20' ROOM 41 FLOOR & LOWER WALLS Beta Scans 5 C:

MAP F8130561 - M2

Room 41 Wall Beta Scans 40 M --- I CONCRETE ELEVATION LOOKING NORTH ELEVATION LOOKING NORT Y 9911103 105 107 1~ 13 1511171120 122 112412

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~ 98 100 102 104, 106 1108 110 1112 1114 116 19121 '123 12

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39 M CONCRETE ELEVATION LOOKING SOUTH Wall juncture scans in red 138 140 142 144 146 148

/137 139 141 143 145 147

-/ 7 / L 13 M ELEVATION LOOKING WEST CONCRETE CONCRETE F1 FVATION I OOKING EAST SC SC t[.

AUXILIARY BUILDING EL. -20 ROOM 41 LOWER WALLS Beta Scans F8130561 - M3

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3? El Room 41 Trench Juncture Scans 57]

AUXILIARY SLDG 118 SO M CONCRETE KEY PLANS Vi~_ii -" / , r . . v.

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FLOOR PLAN" I

AUXILIARY BUILDING EL. -20' ROOM 41 FLOOR & LOWER WALLS C)SMUM SACRAMENTO MUNICIPAL Trench Juncture Scans A A EPN UTILITY DISTRICT MAt- F8130561-M5.

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Page 10 of 14 Att. 1 Maps F8130561 wi Q~

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Attachment 2 Revision 1 Instrumentation May 1, 2008 Survey Unit F8130561

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; 203482 43-68B; 178510 433 1033 M2350; 142499 43-37; 148502 198 616 M2350; 203465 43-116-1B; 216073 491 739 Concrete Juncture M2350, 203465 43-116-1B, 216073 472 3492 Metal Pipe M2350, 203481 44-10, 171992 N/A 5.2 pCi/g Tennelec; 0401171 N/A 6 dpm o, 12 dpmf3 N/A Detector MDC Instrument Serial No. (dpm/1OOcm 2)

InSpector 1000 10054579 7400 Cs-137 3140 Co-60 Table 2-2. Investigation Criteria and DCGL Parameter Value VleC2 (dpm/100 cm 2 )

Investigation Criteria - Direct 141900 Investigation Criteria - Scan 141900 DCGLW 43000 DCGLEMc 141900 Instrument Parameter Value (dpm/1OOcm 2 )

InSpector 1000 DCGLemc for 0.01 m 2 5.55e7 Page 2 of 2 Att. 2 Instrumentation F8130561

Attachment 3 Revision I Investigation May 1, 2008 Survey ,Unit F8130561

Table 3-1 Survey Unit Investigation Investigation Initial Value Investigation Elevated Area Investigation DCGLemc Grid/L'cation Lnvestlgtio Initial Value Result Area (M2) Factor Level (cpm) (cpm) (cpm) (dpm/lOOcm2) Fraction

  • (1) Grid 89 36000 43958 N/A .01 1290 5.55e7 3.33e5 0.0060 DCGL SU Mean =

Survey Unit Remainder 43,000 2646 0.0615 EMC Unity Sum 0:0675 Gamma scans were performed to complete the particle survey and one elevated area was identified. The identified area was further bounded and analyzed with InSpector 1000.

  • Locations on map attached to Download 08-231 Thie-rnUlts are shown in Table 3-1 With results less than unity.

Page 2 of 2 Att. 3 Investigation

Attachment 4 Revision 1 Data Assessment May 1, 2008 Survey Unit F8130561

UQ (V F81 30561 G ross Activity Sample Results Quantile Plot k) 2 0 DCGL = 43000 dpm/lOOcm 4z~.

14,000 12,000 (N 10,000 E

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(V 4,000 2,000 21 60 0

0 20 40 60 80 100 It Percentile 00

  • Direct Measurements (dprn/100cmn2'. median - - -75th Percenlile - - - - 50th Percentile C) 21

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-o (D F8130561 Gross Activity Sample Results Scatter Plot 2

DCGL = 43000 dpml1 00cm 14000 12000 - 0 CI4 Q E 10000 -

a 0 - - - - - - - - - - - - - - - - - - -m 8192 8000 0

6000 -

0 4000 - C 0 0 0 0 0 2646 A 2000 - - - - - - - - - - - - -- _ 0

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SIa Gross Activity Average - ' " StDev -. - L3StDev I

00 F81 30561 Gross Activity Frequency Plot 2

DCGL = 43000 dpm/1 D0Cm 40

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BIn LO (00 CO cw Bins -Upper End Value (dpm/1 00cm2--)

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