ML090900775

Final Status Survey Summary Report for February 24, 2009, Trench 1 Surface, Survey Unit F8100052

ML090900775
Person / Time
Site:	Rancho Seco
Issue date:	02/24/2009
From:	Frank G Sacramento Municipal Utility District (SMUD)
To:	NRC/FSME
Shared Package
ML090830613	List: ML090830313 ML090830314 ML090830316 ML090830318 ML090830319 ML090830320 ML090830321 ML090830322 ML090830323 ML090830324 ML090830541 ML090830542 ML090830543 ML090830544 ML090830545 ML090830546 ML090830547 ML090830548 ML090830573 ML090850549 ML090850550 ML090850551 ML090850552 ML090850553 ML090850554 ML090850555 ML090850556 ML090850557 ML090850558 ML090850559 ML090850560 ML090850561 ML090850562 ML090890534 ML090890535 ML090890536 ML090890537 ML090890539 ML090890584 ML090890585 ML090890586 ML090890587 ML090890588 ML090890727 ML090900729 ML090900730 ML090900731 ML090900732 ML090900733 ML090900770 ... further results
References
DPG 09-097
Download: ML090900775 (18)

Text

Rancho Seco Final Status Survey Summary Report February 24, 2009 Trench I Surface Survey Unit F8100052 Prepared By: "..£__________te:__

_ _FSS Engineer Reviewed By: Date: --0 Lead FSS Engineer Approved By: "7 Date:_______

Dismantlement S rintendent, Radiological FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit: F8100052, Trench 1 Surface Survey Unit

Description:

Operating History: The area surrounded the tanks used to store radioactive liquids. This area was used for the storage of radioactive material.

Operating records and the HSA document several events with the potential for a release of radioactivity associated with this survey area. The HSA documented the storage of radioactive material within the area that may have had the potential to contaminate the area.Records of soil samples taken near the BWST showed soil contamination levels as high as 230 pCi/g prior to remediation.

Site Characterization:

Soil samples were collected and analyzed for the presence of plant-derived radionuclides.

Cs-137 was the primary nuclide of plant origin detected with a mean activity level of 379 pCi/g and a maximum value of 1,040 pCi/g. Based on the classification procedure (DSIP-0020) and levels of Cs-137 reported, the area was determined to be a Class I land area.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 660 m 2 were scanned for approximately 100% coverage.

Soil samples were collected at each direct measurement location and analyzed by HPGe detector.

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 F8100052 Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area: F810 Trench 1 Surface Survey Unit: 0052 Open Land Area Class: 1 LTP Table 5-4 SU Area (m2): 660 Evaluator:

G. Frank DCGL Cs137 surrogate (pCi/g): 51.2 Area Factor: 1.5 Class 1 Design DCGLemc (pCi/g): 79 Class 1 LBGR (pCi/g): 25.6 Default = 50% DCGL Design Sigma (pCi/g): 0.1 DTBD-06-001, Table 5-4D Type I Error: 0.05 Type II Error: 0.05 Nuclide: Cs137 Sample Area (m2): 38.8 Class I Total Area Scanned (M 2): 660 Scan Coverage (%): 100% Class 1 Zl., : 1.645: .1.645 Sign P: 0.99865 Calculated Relative Shift: 256 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: 6.9 Class I Page 3 of 8 FSS Summary Report F8100052 Survey Results: A total of 38 direct measurements were made in F8100052.

The results including mean, median, standard deviation and range are shown in Table 2. All of the direct measurements were less than the DCGL. ISOCS measurements resulted in no Co-60 activity greater than the MDA from Attachment 2, Table 2-1 the range of Co-60 is 0.168 to 0.277 pCi/g. Particle scans of the entire survey area were performed using a 2350-1 w/44-10 with no readings above the investigation criteria in Attachment 2, Table 2-2 the range is 3201 to 4751 cpm. None of the scan measurements indicated areas of elevated activity.Table 2. Direct Measurement Results (all activity values in pCi/g)T Measurement ID Mean: Median: Standard Deviation:

Range: F8100052AOOO1GS 2.21E-01 2.87E-01 1.59E-01 F8100052A0002GS 4.39E-01 < 4.39E-01 F8100052A0003GS 4.01E-01 < 4.01E-01 F8100052A0004GS 4.17E-01 < 4.17E-01 F8100052A0005GS 4.09E-01 < 4.09E-01 F8100052A0006GS 4.05E-01 < 4.05E-01 F8100052A0007GS 2.04E-01 4.01E-01 1.68E-01 F8100052A0008GS 2.40E-01 6.71E-01 2.17E-01 F8100052A0009GS 4.39E-01 < 4.39E-01 F8100052AOOOGS 3.90E-01 < 3.90E-01 F8100052AOO11GS 2.64E-01 3.91E-01 1.92E-01 F8100052A0012GS 2.20E-0 1 3.09E-0 1 1.62E-01 F8100052S0013GS 1.94E-01 3.18E-01 1.51E-01 F8100052S0014GS 4.68E-01 < 4.68E-01 F8100052S0015GS 2.07E-01 4.79E-01 1.78E-01 F8100052S0016GS 2.19E-01 4.75E-01 1.82E-01 F8100052S0017GS 2.1OE-01 2.82E-01 1.53E-01 F8100052S0018GS 1.97E-01 < 1.97E-01 1.25E-01 F8100052S0019GS 2.03E-01 6.45E-01 1.98E-01 F8100052S0020GS 4.18E-01 < 4.18E-01 F8100052S0021GS 2.15E-01 4.81E-01 1.81E-01 F8100052S0022GS 4.64E-01 < 4.64E-01 F8100052S0023GS 3.40E-01 < 3.40E-01 F8100052S0024GS 2.91E-01 < 2.91E-01 F8100052S0025GS 2.06E-01 4.13E-01 1.68E-01 Page 4 of 8 FSS Summary Report F8100052 F8100052S0026GS 3.70E-O1 < 3.70E-01 F8100052S0027GS 1.83E-01 2.59E-01 1.37E-01 F8100052S0028GS 3.70E-01 < 3.70E-01 F8100052S0029GS 3.40E-01 < 3.40E-01 F8100052S0030GS 3.92E-01 < 3.92E-01 F8100052S0031GS 3.97E-01 < 3.97E-01 F8100052S0032GS 1.95E-01 2.59E-01 1.43E-01 F8100052S0033GS 1.86E-01 2.97E-0 1 1.44E-0 1 F8100052S0034GS 1.60E-01 3.11E-01 1.36E-01 F8100052S0035GS 3.57E-01 < 3.57E-01 F8100052S0036GS 3.70E-01 < 3.70E-01 F8100052S0037GS 3.66E-01 < 3.66E-01 F8100052A0038GS 3.92E-01 < 3.92E-01 Page 5 of 8 FSS Summary Report F8100052 Survey Unit Data Assessment:

The survey design required 3 8 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 6 of 8 FSS Summary Report F8100052 Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N): 38 Median (pCi/g): 3.91E-01 Mean (pci/g): 3.87E-01 Standard Deviation (pCi/g): 9.37E-02 Maximum (pCi/g): 6.71E-01 Sign Test Final N Value: 38 S+ Value: 38 Critical Value: 24 Sufficient Samples Collected:

Yes Maximum Value < DCGL: Yes Median Value < DCGL: Yes Mean Value < DCGL: Yes Maximum Value < DCGLemc: Yes Class 1 Standard Deviation

<= Sigma: Yes Pass the Sign Test? Yes Reject the Null Hypothesis?

Yes The survey unit passes all conditions?

Yes Page 7 of 8 FSS Summary Report F8100052 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, the ALARA criterion has been met.Changes in Initial Survey Unit Assumptions:

The survey unit was designed as a Class 1 land 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 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 F8100052 meets the release criteria of 1OCFR20.1402, Page 8 of 8 FSS Summary Report F8100052 Attachment 1 Maps February 24, 2009 Survey Unit F8100052 0 Trench 1 East Portion -Surface Scan w/44-10 for Discrete Particles//~0 4-_0 0 Cl)Soil I-T LO R-T 1414 1 CZ? 14 1 LIO* I qlcor I I,- "Cr-q-]U?I',',n1 UI) r4n 0 = Gamma Background Asphalt 1061 091~- ~JC~~ U ( f --- -0 O --4 -~ --O -D 1-0 -~ MM 10 *1 1 08H f i l 1 It 00 C)C>tQ t Concrete Gutter Edge F8100052-Mi 0 Trench 1 Eastern Portion ISOCS Scans cd~-o~0_0 0:~0 4--TI 00 IC)Concrete Gutter Edge Measurements are center to center, unless noted by an arrow F8100052-M2 Attachment 2 Instrumentation February 24, 2009 Survey Unit F8100052 Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model MDC No.No.Soil -0.468 pCi/g Cs-137 ISOCS N/A 2983947 .Soil -0.269 pCi/g Co-60 Asphalt- 0.439 pCi/g Cs-137 Asphalt -0.277 pCi/g Co-60 2350-1 44-10 211672 5 pCi/g 2350-1 44-10 256101 5 pCi/g Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value Soil -51.2 pCi/g Cs-137 Soil -12.6 pCi/g Co-60 ISOCS Investigation Criteria -Scan Sphl -51.2 pCi/g Cs-60 Asphalt -51.2 pCi/g Cs- 13 7 Asphalt -12.6 pCi/g 2350-1 44-10 Particle Scan 8850 cpm All DCGLw 51.2 Cs-137 12.6 Co-60 Design DCGLEMC from Table 1 of FSS All DCGLEMC Summary Report or from DQA Evaluation Summary Page 2 of 2 Att. 2 Instrumentation F8100052 Attachment 3 Investigation February 24, 2009 Survey Unit F8100052 (none required)

Attachment 4 Data Assessment February 24, 2009 Survey Unit F8100052 0 It~00 C:)F8100052 Quantile Plot Cs137 DCGL = 51.2 pCi/g U a.U 0.800 0.700 0.600 0.500 0.400 0.300 0.200 0.100 0.000 0.391 0 .20 40 60 Percentile 80 100 I. Activity -Median ---75th Percentile

---

50th Percentile 0D 0, F~ 00052 Scatter Plot CJ2 F8 100052 Scatter Plot Cs 37 .£CGL = 51.2 pCi/a 8.00E-01 7.00E-01-~ ~ -. ...--. .--. ..- -. ...- -. ...- ------0,668 6.00E-01 s 5.00E-01 000000 0 0 0 0 0 0 0 0 2.00E 4010 4 0 0 0 0 0 0 1 .0E-0I- 0.106< < < < < < 0 c < t. o W 0 to to 0 0o to 0 to 0 0to 0 40 to0 0 W 0 0 00 0 to to Measurement Locations[ Activity -Average --"+3StDev" --"-3StDev ti 00 C)C)C,,,

4r-C/2 00 C/2 (-h1 k)j i F8100052 Frequency Plot Cs1 37 DCGL = 51.2 pCi/g 21 20-19 18 S17 c 16 ai) 15-14 a)13-12-if_ 12 C 1 1 o 10 4: 90~8-7-c)6-Q 5-0 4 3-2-1-0-(N N N N-5 N 2 (y N Bins -Upper End Value (pCi/g)