ML082620106
| ML082620106 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/01/2008 |
| From: | Donna Anderson Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-064 | |
| Download: ML082620106 (24) | |
Text
Rancho Seco Final Status Survey Summary Report April 1, 2008 Center Turbine Deck (+) 40' El.Survey Unit F8260304 Prepared By: !c. Date: 4-//2.,c*'
Reviewed By:_ Date: _____t Engineer" Approved By: Date: 7 Dismantlemeht Sdt drintendent, Radiological FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit: F8260304, Center Turbine Deck (+) 40' El.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/1 00 cm2 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 cm2 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 cm2 and a maximum value of 2,626 dpm/100 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/l100 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 cm2 .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.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 693 m 2 were scanned for approximately 73% 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 8 FSS Summary Report F8260304 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/100 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: 0304 2 953 D. Anderson 43,000 N/A N/A 37,831 1,723 0.05 0.05 Cs-137 68.1 693 73%1.645 1.645 0.99865 3 3 Center Turbine Deck (+) 40'El.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 11 14 14 8.2 Page 3 of 8 FSS Summary Report F8260304 Survey Results: A total of 16 direct measurements were made in F8260304.
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.
All ISOCS gamma measurements were less than the Cs-137 and Co-60 MDAs.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 F8260304-MOO01 BD F8260304-MOO02BD F8260304-MOO03BD F8260304-CO004BD F8260304-COOO5BD F8260304-CO006BD F8260304-CO007BD F8260304-CO008BD F8260304-CO009BD F8260304-COOIOBD F8260304-COOI I BD F8260304-CO01 2BD F8260304-CO01 3BD F8260304-CO014BD F8260304-CO015BD F8260304-CO01 6BD Mean: Median: Standard Deviation:
Range: 2,302 2,508 2,413 1,971 2,049 1,727 1,276 2,251 2,049 2,039 2,044 2,018 1,950 1,701 2,646 1,701 2,040 2,041 343 1,276 -2,646 Page 4 of 8 FSS Summary Report F8260304 Table 3. Removable Surface Activity Results Measurement ID .Surface Beta Activity (dpmll00 cm 2)F8260304M0001 SM F8260304M0002SM F8260304M0003SM F8260304C0004SM F8260304C0005SM F8260304C0006SM F8260304C0007SM F8260304C0008SM F8260304C0009SM F8260304C0010SM F8260304C001ISM F8260304C0012SM F8260304C0013SM F8260304C0014SM F8260304C0015SM F8260304C0016SM Mean: Median: Standard Deviation:
Range:-3.53 1.64-4.82-0.95-3.53 1.64 0.34 0.34 0.34-0.95-2.24-3.53-2.24-2.24 8.09-4.82-1.03-1.59 3.21-4.82 to 8.09 Page 5 of 8 FSS Summary Report F8260304 Survey Unit Data Assessment:
The survey design required 16 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 F8260304 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): 16 Median (dpm/100 cm 2): 2,041 Mean (dpm/lO0 cm 2): 2,040 Direct Measurement Standard Deviation 343 (dpm/100 cm 2): Total Standard Deviation (dpm/100 cm 2): 343 Based on samples and backgrounds.
Maximum (dpm/100 cm 2): 2,646 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 16 S+ Value: 16 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 F8260304 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 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. No potential areas of elevated activity were detected.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/1 00 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 F8260304 meets the release criteria of IOCFR20.1402.
Page 8 of 8 FSS Summary Report F8260304 Attachment 1 Maps April 1, 2008 Survey Unit F8260304 00 01%00 UN C0 P.F8260303:
North Turbine Deck F8260304:
Center Turbine Deck F8260305:
South Turbine Deck Area Estimate:
815 sq. meters Area Estimate:
953 sq. meters Area Estimate:
847 sq. meters Map F8260304-1, Turbine Building Deck (+) 40' El.Area Estimate:
2,615 sq. meters (3 survey units -Class 2)N 0 2 4 6 8 Distance in Meters Location of Turbine Building inside the Industrial Area 95 ft.- 29 m N Map F8260304-2, Center Turbine Deck (+) 40' El.o 2 4 6 8 Area Estimate:
953 sq. meters stane in Meters Page 3 of 9 Att. 1 Maps F8260304 0 00 0j-C>
Distance in meters from west edge of turbine deck 15D 34D 38.1 m 0 0 q1 0 o 0 0 o __o 0 30.6 mD8D 2 .m.. .35.0m 27.5m m 0. a Map F8260304-4, Center Turbine Deck (+) 40' El.a CD Beta Direct Measurements F8260304M0001BD to F8260304M0003BD, F8260304C0004BD to F8260304C0006BD, F8260304M0007BD and F8260304C0008BD to F8260304C0016BD 7.5 m bv 7.5 m ard sDacina 0 24 6 8 O~islnc in Meters Page 5 of 9 Att. 1 Maps F8260304 0(0 pC F8260303:
North Turbine Deck 42 ISOCS Gamma Scan Measurements F8260304:
Center Turbine Deck 53 ISOCS Gamma Scan Measurements F8260305:
South Turbine Deck 22 ISOCS Gamma Scan Measurements 00 0 N 024 68 Distance in Mot=Map F8260304-5, Turbine Building Deck (+) 40' El.ISOCS Gamma Scan Measurements 12.57 sq. meter field of view D fr 047GeS 48 S e49GE-ES 50GS 51GS 52GS 53GS C 0 0 0 46 S S 43GS 42GS 41 GS 40GS 0 34GS 35 S S 39GS A 31 S GS 30GS 29GS 28GS 27GS 20GS 21GS 22GS 23GS 24GS -25GS 26GS 0 0 N, 4.1111, 00 istance in meters om west edge of turbine deck.37.7 m-34.2 m-30.7 m 27.2 m 23.7 m 19GS Low su pen)pan__I , C C C C 6 Lo~w/T (01Iý-s)ure 18GS 17GS20.2m 15GS S 9.7 m 3S 9-.-8-- 6.2 m~s G 12S 11 0 2GS 3GS I 4GS T 1GS 5GS 6GS k7GS 1 -2.AN, ~ ~ j 1~ .(5&g-44 I 30 0 2. 4 6 8 pista-c in Mwola 3 3 3 B] 3 3B 3 Map F8260304-6, Center Turbine Deck (+) 40' El.ISOCS Gamma Scan Measurements F8260304C0001 GS to F8260304C0053GS, 12.57 sq. meter field of view Approximate Scan Area: 607 sq. meters 2.7 m=: CD0.Page 7 of 9 Att. 1 Maps F8260304 00 0 00 t'ON 1W 1 I1 F8260304:
Center Turbine Deck 4 ISOCS Gamma Scan Measurements on Turbine Deck boxes N._0 2 4 6 8 O~i_?'- i. ME~er Map F8260304-7, Turbine Building Deck (+) 40' El.ISOCS Gamma Scan Measurements F8260304C0054GS to F8260304C0057GS 11.8 sq. meter field of view Approximate Scan Area: 47 sq. meters N ---or==VNNEZ=ý0 2 4 6 8 Diswnm in Metem Map F8260304-8, Center.Turbine Deck (+) 40' El.Beta Scan Measurements F8260304M0001BS to F8260304M0037BS, Approximate Scan Area: 39 sq. meters Page 9 of 9 Att. 1 Maps F8260304 Attachment 2 Instrumentation April 1, 2008 Survey Unit F8260304 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; 175834 43-68B; 190482 433 1,033 M2350; 175834 43-68B; 148634 433 1,033 M2350; 193715 43-68B; 148630 433 1,033 Tennelec; 0401171 N/A 5.88 dpm t, N/A 11.71 dpm P3 MDC Concrete -1,420 dpm/100 cm' Cs-137, Concrete -740 dpm/100 cm 2 Co-60 Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2)Investigation Criteria -Direct 43,000 Investigation Criteria -Scan 4,300 (ISOCS average activity)DCGLw 43,000 DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8260304 Attachment 3 Investigation April 1, 2008 Survey Unit F8260304 (none required)I Attachment 4 Data Assessment April 1, 2008 Survey Unit F8260304 CD ct-00 Q)F8260304 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm 2 I: 4..3,500 3,000 2,500.2,000 1,500 1,000 500 0 2041 0 20 40 60 80 100 Percentile
- Direct Measurements (dpm/1 00cm2) median ---75th Percentile
.50th Pbrcentile CD (U o VF8260304 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmlO00=cn 3500 3000 -.-.-.-----------------.-----.-------
0 E 0 82500 0 0 0 0 2000 --- -O- .2040 S1500>' 0 CD 1000 -------------------------1012 CD)<500 0 1 I I I I I 'O 0 r r t- t- r t-o C 0 01 a 0 0 0 0 0 0 0 0 0 0 a U U U U U U U U U U U U Measurement Locations I [o Gross Activty- Average --"+3StDev" -%--3StDev NA 0 0cj)F8260304 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm 2 5 C j 4 3 2 1 0 (0 C" 83 I..-0)S CO It1 00 Bins -Upper End Value (dpm/1 00cm2)