ML081610234

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Final Status Survey Summary Report, Room 114, 136, 137, Survey Unit F8131021
ML081610234
Person / Time
Site: Rancho Seco
Issue date: 02/11/2008
From:
Sacramento Municipal Utility District (SMUD)
To:
NRC/FSME
References
MPC&D 08-032
Download: ML081610234 (26)
v • d • e


Text

Rancho Seco Final Status Survey Summary Report February 11, 2008 Room 114,136, 137 Survey Unit F8131021 Prepared By Date: 2)/ -

Reviewed Date:

Approved By:_ ý' _ _ _ Date: ___-__-_

Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F813 1021, Room 114, 136, 137, Make-Up Valve and Filter Rooms 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 320,07.1 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/1 00 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 cm 2 and a maximum value of 5,800,000 dpm/100 cm 2 . Direct measurements on the +20' elevation showed a meangross activity level of 85,408 dpm/100 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 242.5 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 F8131021

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

.Survey Area: F813 Room 114, 136, 137 Survey Unit: 1021 Structure Surface Class: 1 LTP Table 5-4 SU Area (m2): 242.5 Evaluator: Gary Frank DCGL (dpm/IO0 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 cm): 6935 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 CO-60 used. for Area factor and emc Sample Area (m2): 7 Class 1 Scan Area (m ): 2 242.5 Scan Coverage (%): 100% Class I Zl-[, " 1.645 1.645 Sign P: 0.99865 Calculated Relative Shift: 3.1 Relative Shift Used: 3 Uses 3.0 if Relative Shift is

>3 N-Value: 11 Design N-Value + 20%: 14 NUREG-1575 Table 5-5 Design Min Samples N: 35 *Class 1

.Grid Spacing L: 2.6 Class 1 Page 3 of 9 FSS Summary Report F8131021

Survey Results:

A total of 46 direct measurements were made in F8131021. 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 1033 (MDA) to 81018 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 Activit.

(dpm/100 cm

  • F8131021-CO001BD 1214 F8131021-CO002BD 1266 F8131021-CO003BD 1069 F8131021-CO004BD 1146 F8131021 -CO005BD 1359 F8131021-CO006BD 1385 F8131021-CO007BD 1110 F8131021-CO008BD 1344 F8131021-COOO9BD 1333 F8131021-COOIOBD 1442 F8131021-CO011BD 1318 F8131021-CO012BD 1478 F8131021-CO013BD 1261 F8131021-CO014BD 1302 F8131021-CO015BD 1219 F8131021 -CO016BD 1063 F8131021-CO017BD 1193 F8131021-CO022BD 1525 F8131021-C0023BD 1421 F8131021-C0o24BD 1188 F8131021-CO025BD 1416 F8131021-CO026BD 1836 F8131021-CO027BD 4736 F8131021-CO028BD 3149 F8131021-CO029BD 8149 F8131021-CO03OBD 1468 F8131021-CO031BD 1722 F8131021-CO032BD 2811 F8131021-CO033BD 1961 F8131021-CO034BD 1390 F8131021-CO035BD 1753 F8131021-CO036BD 1655 F8131021-COO37BD 1354 F8131021-CO038BD 2111 F8131021-CO039BD 1769 F8131021-C004OBD 3595 F8131021-CO041BD 3465 Page 4 of 9 FSS Summary Report F8131021

Measurement ID Gross Activity (dpm/1 00 cm F81 31021 -CO042BD 1344 14 F81 31021 -CO043BD 1328 12 F81 31021 -CO044BD 1219 11 FBI131021 -CO045BD 1385 18 F8I131021 -COO46BD 1411 11 FBI131021 -CO047BD 1406 10 F81 31021 -COO48BD 1027 12 F813l021-COO49BD 1312 11 FBI131021 -COOSOBD 1338 13 1777 1385 Standard Deviation:.16 .1216 1027 -8149 Ranqe: 1027-8149 Page 5 of 9 FSS Summary Report F8131021

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

F8131021 CO001SM -4.82 F8131021 C0002SM 4.22 F8131021CO0003SM 8.09 F8131021 C0004SM -3.53 F8131021CO005SM -4.82 F8I31021C0006SM 0.34 F8131021 C0007SM 0.34 F8131021CO008SM -4.82 F8131021CO009SM -4.82 F8131021 Co010SM 0.34 F8131021CO011SM -0.95 F8131021 Co012SM -3.53 F8131021 Co013SM -2.24 F8131021 CO014SM 0.34 F8131021 Cooi5SM 0.34 F8131021 Co016SM 0.34 F8131021 Co017SM -4.82 F8131021CO022SM 1.64 F8131021 C0023SM -0.95 F8131021 C0024SM 4.22 F8131021 C0025SM -3.53 F8131021 C0026SM -0.95 F8131021 C0027SM -2.24 F8131021 C0028SM 2.93 F8131021 C0029SM 2.93 F8131021 C0030SM 1.64 F8131021 C0031 SM -2.24 F8131021 C0032SM -0.95 F8131021 C0033SM -0.95 F8131021 C0034SM -2.24 F8131021 C0035SM -2.24 F8131021 C0036SM 1.64 F8131021 C0037SM -3.53 F8131021 C0038SM 1.64 F8131021 C0039SM 1.64 F8131021 C0040SM 35.21 F8131.021 C0041 SM 61.04 F8131021 C0042SM -2.24 F8131021 C0043SM -3.53 F8131021 C0044SM -2.24 F8131021 C0045SM -3.53 F8131021 C0046SM -3.53 F8131021 C0047SM 0.34 F8131021 C0048SM 0.34 F8131021 CO049SM 0.34 F8131021 COO5OSM -0.95 Mean: 1.3 Median: -0.95 Standard Deviation: 10.82 Range: = -4.82 to 61.04 Page 6 of 9 FSS Summary Report F8131021

Survey Unit Data Assessment:

The survey design required 46 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 F8131021

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): 46 Median (dpm/100 cm2): 1385 Mean (dpm/100 cm 2): 1777 Direct Measurement Standard Deviation 1216 (dpm/100 cm 2):

Total Standard Deviation (dpm/100 cm 2): 1216 Based on samples and backgrounds.

Maximum (dpm/100 cm 2): 8149 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 46 S+ Value: 46 Critical Value: 29 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 F8131021

Survey Unit Investigations and Results:

No investigations were required for either direct or scan measurements and no investigation results are reported.

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 No potential areas of elevated activity were detected. 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 .ofthe 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. No investigations were required.

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 F8131021 meets the release criteria of 10CFR20.1402.

Page 9 of 9 FSS Summary Report F8131021

Attachment 1 Maps February 11, 2008 Survey Unit F8131021

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Attachment 2 Instrumentation February 11, 2008 Survey Unit F8131021

Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan 2

Model; Serial No. Model; Serial No. (dpm/100 cm ) (dpm/100 cm 2 )

M2350;- 180733 43-98B; 148638' 550 990 M2350; 180733 43-94; 148620' 350 610 M2350; 175834 43-68B; 1904821 433 1033 M2350; 203486 43-68B; 190476' 433 1033 M2350; 193700 43-68B; 1902941 433 1033 M2350; 203486 43-68B; 1614001 433 1033 M2350; 149789 43-68B; 161397' 433 1033 M2350; 193715 43-68B; 160703' 433 1033 M2350; 149789 43-116-IB; 256006' 796 3258 M2350; 175834 43-116-1B; 1906423 796 3258 M2350; 203486 43-116-IB; 1901732 491 739 M2350; 180733 43-1liB; 1486416 360 660 M2350; 180733 43-111B; 1486417 730 1320 5.9 dpm a, Tennelec; 0401171 N/A dpm N/A

_11.9 dpm 3 143-68B Concrete Surface '43-116-1B 4

Concrete Juncture 343-116-1B Concrete Surface 43-94B 1" Metal 5

43-98B 2" Metal 643-11B 1" Metal 743-111 B 2" Metal Table 2-2. Investigation Criteria and DCGL Parameter Value (dpm/100 cm2)

Investigation Criteria - Direct 141900 Investigation Criteria - Scan 141900 DCGLw 43000 DCGLEMC 141900 Page 2 of 2 Att. 2 Instrumentation F8131021

Attachment 3 Investigation February 11, 2008 Survey Unit F8131021 (none required)

Attachment 4 Data Assessment February 11, 2008 Survey Unit F8131021

F81 31021 Gross Activity Sample Results Quantile Plot DCGL =43000 dpmlO0Ocm 2 9,000 8,000 ~iL.a

"* *E 5,000  :"

  • 3,0004681 2,000 135 0 20 40 60 80 100 Percentile I Direct MeasuIreme*nts (dpm/1 00cmr2) - median 75th Percentile 50th Percentile

a*

0q FBI 31021 Gross Activity Sample Results Scatter Plot 2

DCGL = 43000 dpmll 00cm 10000 8000 E 6000 0

CD - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5425 C1 4000 V-p 2000 00 0_ 0 000000 00: 1777 IC 0

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-+3StDev -.. "-3StDev'l

0 F81 31021 Gross Activity Frequency Plot 2

DCGL = 43000 dpm/100cm 41 95

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