ML090890585
| ML090890585 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 07/04/2008 |
| From: | Andersen D Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097, F8260032 | |
| Download: ML090890585 (28) | |
Text
Rancho Seco Final Status Survey Summary Report July 4, 2008 Turbine Building (+) 0' El., Main Feed Pump Area Survey Unit F8260032 Prepared By: cs,. UADCt--FSS Engineer Reviewed By: _______Lead FSS Engineer Date: 1/ I8 Date: I jk jo Approved By: $ Date: _ 27 -Dismantlement Sup intendent, Radiological FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit: F8260032, Turbine Building (+) 0' El., Main Feed Pump Area Survey Unit
Description:
Operating History: The reinforced concrete and steel structure contained the turbine-generator and supporting systems. The building contained five 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 in the condenser pit elevation showed a mean gross activity level of 3,077 dpm/100 cm 2 and a maximum value of 24,900 dpm!100 cm 2.Direct measurements on the grade elevation showed a mean gross activity level of 2,035 dpm/100 cm 2 and a maximum value of 6,980 dpm/100 cm 2.Direct measurements on the mezzanine elevation showed a mean gross activity level of 1,566 dpm/100 cm 2 and a maximum value of 2,626 dpm/1 00 cm 2.Direct measurements on the +40' elevation showed a mean gross activity level of 2,843 dpm/100 cm 2 and a maximum value of 3,615 dpm/100 cm 2.Direct measurements on the building exterior showed a mean gross activity level of .1,984 dpm/100 cm 2 and a maximum value of 10,312 dpm/100 cm 2.Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the interior of the turbine building was determined to be Class 1, 2, & 3 areas and the exterior was a Class 3.During FSS surveys of F8260032 (Turbine Building (+) 0' El., Main Feed Pump Area, Class 2), beta measurements identified activity within a 1-meter by 5-meter area that exceeded the DCGL of 43,000 dpm/1 00 cm 2.The area was subsequently removed from this survey package, remediated and reclassified as a Class 1 structure, based on the classification procedure (DSIP-0020).
Final surveys of the Class 1 area will be performed undersurvey package F8260171.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 100 m 2 were scanned for approximately 54% 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 inTables 2-1 and 2-2 in Attachment 2.Page 2 of 8 FSS Summary Report F8260032 Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F826 Survey Unit: Class: SU Area (m2): Evaluator:
DCGL (dpm/100 cm 2): Area Factor: Design DCGLemc (dpm/1 00 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 (%): ZIp: Sign P: Calculated Relative Shift: Relative Shift Used: N-Value: Design N-Value + 20%: Design Min Samples N: Grid Spacing L: 0032 2 186.2 D. Anderson 43,000 N/A N/A 25,030 5,990 0.05 0.05 Cs-137 13.3 100 54%1.645 1.645 0.99865 3 3 11 14 14 3.0 Turbine Building (+) 0' El., Main Feed Pump Area Structure Surface LTP Table 5-4 Gross Activity DCGL Class 2 Class 2 Adjusted Class 2 Class 2 Uses 3.0 if Relative Shift is>3 NUREG-1575 Table 5-5 Class 2 Class 2 Page 3 of 8 FSS Summary Report F8260032 Survey Results: A total of 15 direct measurements were made in F8260032.
The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. Two of the beta scan measurements indicated areas of elevated activity.
Scan activity ranged from 4,218 to 68,000 dpm/100 cm 2 , based on a surveyor efficiency of 0.5 and no background subtracted.
The scan grids indicating elevated activity were removed from the survey unit, remediated and resurveyed under FSS Package F8260171.
As left beta scan measurements ranged'from 4,218 dpm/100 cm 2 to 8,818 dpm/100 cm 2.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/lO0 cm F8260032-CO001 BD F8260032-CO002BD F8260032-CO003BD F8260032-CO004BD F8260032-CO005BD F8260032-CO006BD F8260032-CO007BD F8260032-CO008BD F8260032-CO009BD F8260032-COOIOBD F8260032-COOI 11BD F8260032-CO012BD F8260032-CO013BD F8260032-CO014BD F8260032-CO01 5BD Mean: Median: Standard Deviation:
Range: 2,552 1,712 1,577 1,784 1,644 2,485 2,329 2,111 1,930 2,288 2,770 1,686 1,924 1,867 2,039 2,047 1,930 365 1,577 -2,770 Page 4 of 8 FSS Summary Report F8260032 Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)F8260032C0001 SM F8260032C0002SM F8260032C0003SM F8260032C0004SM F8260032C0005SM F8260032C0006SM F8260032C0007SM F8260032C0008SM F8260032C0009SM F8260032C0010SM F8260032C0011SM F8260032C0012SM F8260032C0013SM F8260032C0014SM F8260032C0015SM Mean: Median: Standard Deviation:
Range:-2.24-0.95 5.51 1.64 10.68-3.53-2.24-3.53 2.93-0.95 1.64-0.95-4.82-0.95 0.34 0.17-0.95 3.96-4.82 to 10.68 Page 5 of 8 FSS Summary Report F8260032 Survey Unit Data Assessment:
The survey design required 15 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 6 of 8 FSS Summary Report F8260032 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): 15 Median (dpm/100 cm 2): 1,930 Mean (dpm/100 cm 2): 2,047 Direct Measurement Standard Deviation 365 (dpm/100 cm 2): Total Standard Deviation (dpm/100 cm 2): 365 Based on samples and backgrounds.
Maximum (dpm/100 cm 2): 2,770 Material-Type:
N/A Background Subtract Not Applied Sign Test Final N Value: 15 S+ Value: 15 Critical Value: 11 Sufficient Samples Collected:
Yes Maximum Value < DCGL: Yes Median Value < DCGL: Yes Mean Value < DCGL: Yes Maximum Value < DCGLemc: N/A Class 2 Total Standard Deviation
<= Sigma: Yes Pass the Sign Test? Yes Reject the Null Hypothesis?
Yes Does the Survey Unit Pass All Criteria?
Yes Page 7 of 8 FSS Summary Report F8260032 Survey Unit Investigations and Results: Two investigations (scan grids 102 and 103) were required for the scan measurements and the results are reported in Attachment
- 3. As a result of the investigation measurements, Grids 102 through 106 were removed from the survey unit package and will be surveyed as a Class 1 structure under F8260171.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 2 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. Two potential areas of elevated activity were detected and evaluated as shown in Attachment 3.Conclusion:
The FSS of this survey unit was properly designed as a Class 2 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 43,000 dpm/100 cm 2 and none of the removable surface activity measurements exceeded 10% of the DCGL. Two 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 F8260032 meets the release criteria of 1OCFR20.1402.
Page 8 of 8 FSS Summary Report F8260032 Attachment 1 Maps July 4, 2008 Survey Unit F8260032 UQ Il m~O L FwZD (."1,0"' :"- Jo: Location of Turbine Building inside the Industrial Area 00 .......S Map F8260032-1, Turbine Building Main Feed Pump Area Location of Turbine Building at Rancho Seco site 0 7 89 10 11 12 13 11W Ki 14 LIZ 00 N Map F8260032-2, Turbine Building Grade and Below Elevations Location of Main Feed Pump Area CD 00 k)j C/\UT1 00j 4 N 7-_/:/13/5 r////, HPPedestal North 111A V77/Pý~eetalI Nroth / /1 Red numbers denote specific vertical surfaces.0 0.5 1.0 1.5 2.0 Distance in Meters Map F8260032-3, Turbine Building Main Feed Pump Area Horizontal Surfaces Area Estimate:
1,363 sq. ft. -126.6 sq. meters 0Q 1-t=0 03.-~. I 43 Looking North South LokJng South Looking East North Looking East Lo[ West 41 Norho"i E Lookisg West Looking North Looking East-'i'll__ ~1~rt.-,s~-44 F2l Looking West South or Looking West Look*ng North Looking East West South East South East West South West South East Looking South North West Looking North East Looking North West Looking North North 08 F 120 W-West Looking South West East Looking South East Map F8260032-4, Turbine.Building Main Feed Pump Area Vertical Surfaces Area Estimate:
641 sq. ft. -59.6 sq. meters It 00 C)0 0.5 1t.0 1.5 2.0 Distance in Meters Main Feed Pump Area Looking West Map F8260032-5, Turbine Building Main Feed Pump Area Views looking West and East Page 6.of 12 Att. I Maps F8260032 Main Feed Pump Ai g South (SW Corner)Map F8260032-6, Turbine Building Main Feed Pump Area NW Corner and SW Corner Page 7 of 12 Att. 1 Maps F8260032 Main Feed Pump Area Looking North (N... ", I ,.r -I Corner)g boutn (,5t Corner)Map F8260032r7, Turbine Building Main Feed Pump Area NE Corner and SE Corner Page 8 of 12 Att. 1 Maps F8260032 I I I I I I I I iI I I f 1 f I Ff1L-i.----
b I -1 1 Map F8260032-8, Turbine Building -- -Main Feed Pump Area Random Start Location-o ----', fra'4 ;sur/ey = nit P PE ,Il N r-- T I-eJetlN;
k -I n nil tas ,~kn wetRA i-71 I. d roi 9' 4P W esLtig oh gE s ooknL)iL o hin Es... --i T -Eaost L i t-Wh -- Looking tf 10 -fr -, Lw _j.-Nc ook- W ast -Lc kin g o 1 -:Ea;- gtis Lst"kingf-N th E--- ýN h Ust ~__ I __ I I II- 1 o. Eas o &S g LooKing out L ao n su 10 15 20 25 30 Page 9 of 12 Att. I Maps F8260032 FE C)~0 E E E E Distance in meters from East border of 00 C')C,)Uj Map F8260032-9, Turbine Building Main Feed Pump Area Beta Direct Measurements F8260032C0001BO to F8260032C0015BD 3.0 m by 3.0 m grid spacing 0 0.5 1.0 1.5 2.0 Distance in Meters CD'00 C')Map F8260032-10, Turbine Building Main Feed Pump Area Beta Scan Measurements F8260032C0001BS to F8260032C0101BS Approximate Scan Area: 100 sq. meters 0 0.5 1.0 1.5 2.0 Distance in Meters 0 79BS 8OBSEI 74BS I 78BS 77BS 76BS 75BS 73BS 72BS L 67BS 68BS 69BS 70[S 66BS 65BS 64BS 63LB 2-- _71 BS 81 BS E I 62BS 82BS I7BS 61 BS 58BS 59BS_F1 46B I 47BS M)m io I ,tooIHI U)4LO.11 50BS 53BS 2ýp's nBS FIJ]JBS 5 FITBS] 52BSýW 38BS 37K 101 I I I I , I U)Co 42BS 40BS 39B~4 Ir1 00 tIN U)tN (-)3' El.(-)6'EI. [()3.5' El. [(-) 1'El.(-) 1.5' El. Li (+) O' El. LI Map F8260032-11, Turbine Building Main Feed Pump Area Beta Scan Measurements Removed from survey unit: F8260032C0102BS to F8260032C0106BS 0 0.5 1.0 1.5 2-0 Distance in Meters Attachment 2 Instrumentation July 4, 2008 Survey Unit F8260032 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; 193700 43-68B; 190294 433 1,033 Tennelec; 0401171 N/A 5.88 dpma, N/A Tennele_;_040117
____ /A_____11.71 dpm]3 N/A Table 2-2. Investigation Criteria and DCGL Value ParameterVau M (dpm/100 cm 2)Investigation Criteria -Direct 43,000 Investigation Criteria -Scan 43,000 DCGLw 43,000 DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8260032 Attachment 3 Investigation July 4, 2008 Survey Unit F8260032 Table 3-1 Survey Unit Investigation 1 Investigation measurements indicated activity exceeding the DCGL of 43,000 dpm/1 00 cm 2 for a Class 2 area. Grids 102 through106 were deleted from the survey unit and will be surveyed under FSS package F8260171.Page 2 of 2 Att. 3 Investigation F8260032 Attachment 4 Data Assessment July 4, 2008 Survey Unit F8260032 F8260032 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/100cm 4,000 '757 3,500 .:'o. ,, 3,000 < .--------~- -------.- --~1930.4;-4-;- - -~ 4 ---444 , ..---.> 4 4S ' -.4~ -.- -.-. ---~t4- v.--1,500 ' '2,000 0 0 20 40 60 80 1-00~Percentile 5Direct Measurements (dpm/100cm2)
-median 7te 5 i --w i.44 Ms.>-444 CD U#C F8260032 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmrl00cm=
0 C:)ON r #3'NJ 3500 j0j' 3000 E D 2500 C2000 S 15001000< 500 0 0 0 00 0 0 0 0 0 n m m m m m n m u ma0 0m m m m m.. a.a..a.a.
a .. .. -_-"-I- --a ! a...a..a a l- 1 a a -..... -a....3142 2047 1951 0 r fl 0 0 0 0) 0 r CN 4 0 o 0 0 0 0 0 0 0 r -0t-a a an a a a a a a a a0 a a a) a UU U U U U U U U U ,U U U U U Measurement Locations oGross Activity -Average "+3StDev-"-
"-3StDev m a __________
I CD a cj~CD CD F8260032 Gross Activity Frequency Plot DCGL = 43000 dpmn/1 00cm 2 4 C 0)2)C 3 -2 1 0 -N~ t o) 0-It 00 UO k)Bins -Upper End Value (dpm/1 00cm2)