ML090830546
| ML090830546 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 02/08/2009 |
| From: | Brown E L Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097, F8080031 | |
| Download: ML090830546 (18) | |
Text
Rancho Seco Final Status Survey Summary Report February 8, 2009 Cooling Tower Buffer (South)Survey Unit F8080031 Prepared By: Date: 2/1512-60-7 FSS Engineer Reviewed By: _ : loga \Lead FSS Engineer Approved By: -7 Date: --Dismantlement Su erintendent, Radiological FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit: F808003 1, Cooling Tower Buffer (South)Survey Unit
Description:
Operating History: The cooling towers and basins were part of the condenser cooling water system. The paved area comprising the basins was not reported to have been used for the storage of radioactive material.
Operating records and the HSA document one event with the potential for a release of radioactivity associated with this survey area.Site Characterization: Direct measurements were made of the exterior surfaces of the structure which confirmed the presence of plant-derived radionuclides.
Direct structuremeasurements showed a mean gross activity level of 4,952 dpm/100 cm2 and a maximum value of 6,289 dpm/100 cm2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the area was determined to be a Class 2 area.HSA Events: PDQ-930036.
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 1498 m 2 were scanned for approximately 20% coverage.
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 7 FSS Summary Report F8080031 Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area: F808 Cooling Tower Buffer (South)Survey Unit: 0031 Open Land Area Class: 2 LTP Table 5-4 SU Area (m2): 7500 Evaluator:
Erin L. Brown DCGL Cs137 surrogate (pCi/g): 51 .2 Area Factor: N/A Class 2 Design DCGLemc (pCi/g): N/A Class 2 LBGR (pCi/g): 25.6 Default = 50% DCGL Design Sigma (pCi/g): 0.92 LTP, Table 5-4C, Rev. No.1 Type I Error: 0.05 Type II Error: 0.05 Nuclide: Cs137 Sample Area (m2): 536 Class 2 Total Area Scanned (m2): 1498 Scan Coverage (%): 20% Class 2:1.645 ZI-: 1.645 Sign P: 0.99865 Calculated Relative Shift: 27.8 Relative Shift Used: 3 Uses 3.0 if Rel Shift >3 N-Value: 11 Design N-Value + 20%: 14 NUREG-1575 Table 5-5 Grid Spacing L: 23.1 Class 2 Page 3 of 7 FSS Summary Report F8080031 Survey Results: A total of 20 direct measurements were made in F808003 1. The results including mean,median, standard deviation and range are shown in Table 2. All of the direct measurements were less than the DCGL. None of the ISOCS scan measurementsindicated activity above the MDC (3.23E-01 to 4.09E-01) for Cs-137.Table 2. Direct Measurement Results (all activity values in pCi/g)Measurement ID Cs137 MDA Cs137 Activity Uncertainty Mean: 9.66E-0 1 Median: s9.77E-01I Standard Deviation:
- 6.52E-02 Range
- 7.40E-01 to 1.06E00 F8080031 AOOO1GD 1.04E00 < 1.04E00 F8080031 A0002GD 7.40E-01 < 7.40E-01 F8080031 A0003GD 9.93E-01 < 9.93E-01 F8080031 A0004GD 1.OOEOO < 1.OOEOO F8080031 A0005GD 1.02E00 < 1.02E00 F8080031 A0006GD 9.85E-01 < 9.85E-01 F8080031 AOOO7GD 1.03E00 < 1.03E00 F8080031 A0008GD 9.80E-01 < 9.80E-01 F8080031 A0009GD 9.59E-01 < 9.59E-01 F8080031 AOO1OGD 9.79E-01 < 9.79E-01 F8080031 AOO11GD 9.75E-01 < 9.75E-01 F8080031 A0012GD 1.06E00 < 1.06E00 F8080031 A0013GD 9.45E-01 < 9.45E-01 F8080031 A0014GD 9.26E-01 < 9.26E-01 F8080031 A0015GD 9.59E-01 < 9.59E-01 F8080031 A0016GD 9.80E-01 < 9.80E-01 F8080031 A0017GD 9.35E-01 < 9.35E-01 F8080031 A0018GD 9.56E-01 < 9.56E-01 F8080031 A0019GD 9.39E-01 < 9.39E-01 F8080031 A0020GD 9.26E-01 < 9.26E-01 Page 4 of 7 FSS Summary Report F8080031 Survey Unit Data Assessment:
The survey design required 20 direct measurements for the Sign Test. The critical value and the results of the Sign Test are presented in Table 3. 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 5 of 7 FSS Summary Report F8080031 Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N): 20 Median (pCi/g): 9.77E-01 Mean (pCi/g): 9.66E-01 Standard Deviation (pci/g): 6.52E-02 Maximum (pci/g): 1.06E00 Sign Test Final N Value: 20 S+ Value: 20 Critical Value: 14Sufficient Samples Collected:
Yes Maximum Value < DCGL: Yes Median Value < DCGL: Yes Mean Value < DCGL: Yes Maximum Value < DCGLemc: N/A Class 2 Standard Deviation
<= Sigma: Yes Pass the Sign Test? Yes Reject the Null Hypothesis?
Yes The survey unit passes all conditions?
Yes Page 6 of 7 FSS Summary Report F8080031 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 land survey and the sample results are consistent with that classification.
The variability of the survey results was less than thecharacterization 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 scancoverage met the requirement of Table 5-6 of the LTP. All of the direct measurements were less than 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 F8080031 meets the release criteria of IOCFR20.1402.
Page 7 of 7 FSS Summary Report F8080031 Attachment 1 Maps February 8, 2009 Survey Unit F8080031 II I'109 sm, CONCRETE O0 (D 0 ELEVATION RE. AIN. NG_ WALL
` wl')K;N', :-:( i-l-II ELEVATION RETAINING WALLflI",i 12~~iG T KEl "LAN 0 1 2 34 5 SCALE METERS 20 SM CONCRETE ELEVATION RETAINING WALLLOOKING $OUT-4 IT1 COO 00 00 IELEVATION RETAINING WALLNOW:. .')-ýLOCKING SlOUTH
,-6813031E 7371 SM 1888915N ASPHALT/CONCRETE
>6 >6- >6>6>>6 >6'6813874E 18889 15N 681 3874E 1888878N iQE 18N 0 5 10152025 SCALE METERS COOLING TOWER BUFFER GEN ARRGMT SURFACE AREA ESTIMATE F8080031 -M1 ELEVATION RETAININIG WALL N :i!LL OITN N1T 0 ELEVATION RETAINING WALL--: 'OFTH SCALE METERS ELEVATION RETAINING WALL NiO.VIKLY _OOKING _-S5-IH 00 00 ELEVATION RETAINING WALL LOOK;NG SOUTHTAPT PCTINT If'PANJfflk ,61' 14l0 5 10152025 SCALE METERS-1, COOLING TOWER BUFFER* SMUD GAMMA DIRECT MEASUREMENT LOCATIONS SACRAMENTO F8080031 -M2 ei RC RAYMONDII (D 0-RETAIINtNGWAL
______ ,LL WALL(. ?R'U0O,ELEVATION RETAINING WALL-O,1A.L [.O ~ 1iG + FT SCALE METERS HI.5-,7 ELEVATION RETAINING WALL"OMIN-1_LY LOOKING, SOUIH~~~1~"IIELEVATION RETAINING WALL!0At',A LOOJy 3 SGUTH'-00 00 C)0 5 10 15 20 25 N SCALE METERS COOLING TOWER BUFFER GAMMA SCAN MEASUREMENT LOCATIONS F8080031 -M3 RC RAYM4OND:
Attachment 2 Instrumentation February 8, 2009 Survey Unit F8080031 Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model MDC No.NO.Asphalt -4.09E-0l pCi/g Cs- 137Inspector N/A 03069793 Asphalt -1.04E+00 pCi/g Co-60 Asphalt -1.06E00 pCi/g Cs-137 ISOCS N/A 2983947 Asphalt -2.88E-01 pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value ISOCS Investigation Criteria -Scan Asphalt -23 pCi/g Cs-137 All DCGLw 51.2 Cs-137 All DCGL12.6 Co-60 All DCGLEMc NI/A Page 2 of 2 Att. 2 Instrumentation F8080031 Attachment 3 Investigation February 8, 2009 Survey Unit F8080031 (none required)
Attachment 4 Data Assessment February 8, 2009 Survey Unit F8080031 (DJ CD F8080031 Scatter Plot C137 DCGL = 51.2 pClIg 1.40E+00 1.20E+00 -. -...........1,162 00 0 0--.OOE+ 0 ---- 0.968 8.00E-01 - .............-..........-....-------------
0.771 S6.00E-01 CD 4.0OE-01 (U)2.00E-01 O.OOE+O0 i 0 I I Measurement Locations 0 Activlty-Average -"+3StDev"" -"-3SIDev" 00 00 C)C) 0 cjn~I1 00 00 F8080031 Frequency Plot Cs1 37 DCGL = 51.2 pCi/g CU~0 9 8 7 6 5 4 3 2 1 0 x Bins -Upper End Value (pCi/g)