ML051750705

to Maine Yankee Final Status Survey Release Record FR-0200 Yard East Survey Unit 6.

ML051750705
Person / Time
Site:	Maine Yankee
Issue date:	06/20/2005
From:	Olsen C Maine Yankee Atomic Power Co
To:	NRC/FSME
References
FR-0200-06, Rev 0
Download: ML051750705 (21)

Text

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MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0200 YARD EAST SURVEY UNIT 6 A

Prepared By: Date: pa _Rav FSS gineer - ture Printed Name Reviewed By: qL Date:

F pecialist - Signature Lxrf?>oc.. As

^Pvnted Name Reviewed By. Dat4jUNI 2i(2005 Independent Review - Signature Printed Na Approved By: _ Date:

FSSMOdeP Signature Credo 2.AB~c

/Printed Name Approved By: - 0g. llf Date: / o FgSS, MOP - Signature Printed Name Revision 0

MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0200 YARD EAST SURVEY UNIT 6 A. SURVEY UNIT DESCRIPTION FR-0200 Yard East Survey Unit 6 was located in the NE corner of the former "Industrial Area" yard, north of the Turbine Building footprint. The 1907 m2 area was bordered on the north by FR-0800 Survey Unit 1 and FR-0900 Survey Unit 1, on the west by FR-01 11 Survey Unit 20, on the south by FR-0200 Survey Unit 8, and on the east by FR-0200 Survey Unit 7. As shown on map FRO200-6 SITE, this survey unit is approximately centered at coordinates 624,125E and 407,760N using the Maine State Coordinate System (West Zone)

NAD 1927. The location of the survey unit in relation to the Service Building and the surrounding FR-0200 and FR-01 1I survey units is shown on map FRO200-6 REF (Attachment 1). The survey unit is located within the expanded Restricted Area boundary.

Survey Unit 6 is an area composed primarily of soft sandy soil. As shown on map FRO200-6c the survey unit is relatively flat with several depressions caused by remediation activities, including storm drain pipe removal.

B. SURVEY UNIT DESIGN INFORMATION Survey Unit 6 was originally classified per the LTP Revision 4 as a Class 3 survey unit, but was reclassified to Class 1 given its history during decommissioning activities.

The survey unit design parameters are shown in Table 1. Given a relative shift of 1.5, eighteen direct measurements would be required for the Sign Test, but 40 were prescribed as a conservative measure. The 40 measurement locations were based on a systematic square grid with a random start point which are illustrated on map FRO200-6b (Attachment 1).

Direct measurements (soil samples) were collected from required locations and analyzed with laboratory gamma spectroscopy instrumentation.

In accordance with the LTP, scans covering 100% of the 1907 m2 area were required for the Class 1 survey unit. This was accomplished by use of an in situ gamma spectroscopy detector (ISOCS) configured at a 3-meter distance from the surface to obtain overlapping 28-m2 fields of view. The ISOCS detector was positioned perpendicular to the surface.

Locations of the 102 survey scans are shown on maps FRO200-6a and 6c (Attachment 1).

The ISOCS scans were configured to ensure 100% scan coverage of all exposed surfaces within Survey Unit 6. The survey instruments used are listed by model and serial number in Attachment 2 (Table 2-1). Scan MDCs are also listed in Attachment 2 (Table 2-2) and are compared to the DCGL, the investigation level, and the DCGLENIc. The scan MDC is less than the scan investigation level, thus providing high confidence (95% or higher) that an elevated area would be detected in the scanning process. Furthermore, since the investigation level was always less than the design DCGLEr1C, no EMC sample size adjustment was necessary.

FR-0200-06, Revision 0 Page 2 of 21

TABLE I SURVEY UNIT DESIGN PARAMETERS Survey Unit Design Criteria Basis Area 1907 m 2 Class 1, < 2,000 m 2 Based on an LBGR of 2.1 Number of Direct pCi/g, sigma' of 1.33 pCi/g Measurements Required 18 (40 used for design) and a relative shift of 1.5, 18 were required, 40 obtained.

Type I = Type 11 = 0.05 Sample Area 48 m2 1907 M2 / 40 = 48 m2 Sample Grid Spacing 6.9 m (48)12 Scan Grid Area ISOCS scan at 3 meters See Section B Area Factor 1.5 Class I Area, LTP Table 6-12 Scan Area 1907 m2 Class I Area- 100%

Scan Investigation Level 1.0 pCi/g Cs-137 ISOCS investigation levels Scan Inves___t___ Level 0.36 pCi/g Co-60 (Reference 3) 4.2 pCi/g Cs-137 DCGL applied to land outside DCGL 1.52 pCi/g Co-60 the Restricted Area (Reference 1) 6s4 p~i/g Cs-137 DCGL x Area Factor for Design DCGLEMC 6.4 pCifg Co-607 Class I survey unit, per LTP 2.3o-60Section pi/g 5.6.3 C. SURVEY RESULTS A total of 40 direct measurements were performed in Survey Unit 6. Four samples contained detectable Cs-137 with levels of activity greater than the MDA but below the DCGL. One sample contained detectable Co-60 activity above the MDA but below the DCGL. All other.

measurements were below the MDA. The results are presented in Table 2. No investigations were necessary as a result of the direct measurements.

ISOCS gamma scans were performed at 102 locations using an investigation level of 1.0 pCi/g Cs-137 and 0.36 pCi/g Co-60. The gamma scans were performed for a sufficient count time to achieve a Minimum Detectable Activity (MDA) of approximately 16% of the DCGL.

All identified scan activity levels and MDAs were below the investigation levels. Therefore, no investigation surveys were performed as a result of the scan surveys.

LTP Revision 4, Table 5-IC for RCA Yard West, ROI00 (conservative).

FR-0200-06, Revision 0 Page 3 of 21

TABLE 2 DIRECT MEASUREMENTS Cs-137 Uncertainty Co-60 Uncertainty Unitized Value Sample___Number_ (pCi/g) (pCi/g) _(Pci/g) (pCi/g) Unitized___Value_

FRO200061SO01 < 6.52E-02 < 7.25E-02 6.32E-02 FR0200061S002 < 4.47E-02_ < 5.09E-02 4.41E-02 FR0200061S003 l.OlE-O1 3.31E-02 < 6.61E-02 6.74E-02 FR0200061S004 _ 1.OlE-Ol 2.81E-02 < 5.58E-02 6.07E-02 FR0200061S005 < 4.58E-02 < 4.85E-02 4.28E-02 FR0200061S006 < 5.81E-02 < 6.15E-02 5.43E-02 FR0200061S007 < 4.39E-02 < 4.63E-02 4.09E-02 FR0200061S008 < 5.12E-02 < 5.1OE-02 4.57E-02 FR0200061S009 < 5.58E-02 < 5.41E-02 4.89E-02 FRO200061SO10 < 4.76E-02 < 5.28E-02 4.61E-02 FRO200061SO I < 5.15E-02 < 5.62E-02 4.92E-02 FRO200061S012 < 4.95E-02 < 5.75E-02 4.96E-02 FR0200061S013 < 5.71E-02 < 5.59E-02 5.04E-02 FR0200061S014 < 5.07E-02 < 4.83E-02 4.38E-02 FR0200061S015 _ 5.80E-02 3.32E-02 < 7.1OE-02 6.05E-02 FR0200061S016 < 4.64E-02 < 4.91E-02 4.34E-02 FR0200061S017 < 5.93E-02 < 6.64E-02 5.78E-02 FRO200061S018 < 4.18E-02 < 4.49E-02 3.95E-02 FR0200061SO19 < 4.36E-02 < 5.31E-02 4.53E-02 FR0200061S020 < 5.74E-02 < 5.89E-02 5.24E-02 FR0200061S021 < 6.08E-02 < 5.84E-02 5.29E-02 FR0200061S022 < 5.80E-02 < 5.76E-02 5.17E-02 FR0200061S023 < 4.91 E-02 < 5.6913-02 4.91 E-02 FR0200061S024 < 5.06E-02 < 5.21E-02 4.63E-02 FR0200061S025 < 6.99E-02 < 6.2613-02 5.78E-02 FRO200061S026 < 5.03E-02 < 5.48E-02 4.80E-02 FR0200061S027 < 5.61E-02 < 5.84E-02 5.18E-02 FR0200061S028 _ 2.25E-01 4.62E-02 _ 2.24E-O1 5.26E-02 2.01E-O1 FRO200061SO29 < 4.78E-02 < 5.OOE-02 4.43E-02 FRO200061S030 < 5.33E-02 < 5.19E-02 4.68E-02 FR0200061S031 < 5.7213-02 < 6.28E-02 5.4913-02 FR0200061S032 < 3.93E-02 < 4.1313-02 3.65E-02 FR0200061S033 < 5.98E-02 < 5.6913-02 5.17E-02 FR0200061S034 < 4.77E-02 < 5.34E-02 4.65E-02 FR0200061S035 < 5.44E-02 < 5.7413-02 5.0713-02 FR0200061S036 < 3.9913-02 < 4.32E-02 3.79E-02 FR0200061S037 < 5.6313-02 < 6.22E-02 5.4313-02 FR0200061S038 < 4.52E-02 < 4.81E-02 4.24E-02 FR0200061S039 < 5.20E-02 < 5.1413-02 4.62E-02 FRO200061S040 < 4.12E-02 < 4.77E-02 4.1213-02 Mean 5.86E-02 5.93E-02 5.3013-02 Median 5.1813-02 5.53E-02 4.9013-02 Standard Deviation 2.99E-02 2.76E-02 ____2.5013-02 Range 3.9313-02 to 2.25E-01 4.131E-02 to 2.24E-0I 3.6513-02 to 2.011E-0I

"<" indicates MDA value. Bold indicates positive detection value FR-0200-06, Revision 0 Page 4 of 21

D. SURVEY UNIT INVESTIGATIONS PERFORMED AND RESULTS Based on the scan results, no investigations were required.

E. SURVEY UNIT DATA ASSESSMENT An analysis of the direct sample measurement results, including the mean, median, standard deviation and sample result range, is provided in Table 2. Positively detected values are bolded in the table. Of the 40 soil samples collected, four identified Cs-137 activity below the DCGL value of 4.2 pCi/g and one sample identified Co-60 activity below the DCGL value of 1.52 pCi/g. All other values were below the MDA. Identified sample activities or Minimum Detectable Activities are listed in Table 2. The mean and median activities were less than the DCGLs for Cs-137 and Co-60. The average of the unity measurements was 0.053 indicating that the direct measurements averaged 5.3% of the DCGL limit.

For illustrative purposes, as indicated in LTP Section 5.9.3, a simplified general retrospective dose estimate can be calculated from the average residual contamination level by subtracting the mean fallout Cs-137 value (0.19 pCi/g)2 for disturbed soil from the survey unit sample mean activity (0.059 pCi/g). This would equate to an annual dose rate of 0.0 mrem/year.

Taking into account the average residual contamination for Co-60, the annual dose rate would equate to 0.39 mrem/yr>. Also, for purposes of demonstrating compliance with the radiological criteria for license termination and the enhanced State of Maine criteria, background activity was not subtracted from the sample analysis activity values.

F. ADDITIONAL DATA EVALUATION Attachment 4 provides additional data evaluation associated with this Survey Unit, including relevant statistical information. Based on survey unit direct measurement data, this attachment provides the Sign Test Summary, Quantile Plot, Histogram, and Retrospective Power Curve.

1. The Sign Test Summary provides an overall summary of design input (Table 1) and resulting calculated values used to determine the required number (N) of direct measurements (per LTP Section 5.4.2). The Sign Test Summary is a separate statistical analysis that also calculates the mean, median, and standard deviation of the direct measurements.

The critical value and the result of the Sign Test are provided in the Sign Test Summary table, as well as a listing of the key release criteria. The direct measurements clearly pass the Sign Test. The subject release criteria have been satisfied. In addition, the sample standard deviation is smaller than the design sigma; therefore, no additional samples were required.

2 See Attachment E to Maine Yankee Procedure PMP 6.7.8 (Reference 2).

3 This annual dose is based on LTP Section 6.7, which shows the contaminated soil contribution (for soils contaminated at the DCGL) to be 10 mrem/y. Therefore, the annual Co-60 dose rate (using the Co-60 DCGL of 1.52 pCilg outside the RA and the mean Co-60 direct activity value of 0.059 pCi/g) would equate to Anneal Dose Rate =10 x( 52)=0.39mrem/y.

FR-0200-06, Revision 0 Page 5 of 21

2. The Quantile Plot was generated from the unity data listed in Table 2. The data set and plot are consistent with expectations for a Class I survey unit. All of the measurements are below the DCGLs of 4.2 pCi/g (Cs-137) and 1.52 pCi/g (Co-60) for land outside the Restricted Area.

3. A Histogram Plot was also developed. This plot shows a log-normal distribution with one outlier.

4. A Retrospective Power Curve was constructed, based on FSS results. The curve shows that this survey unit having a mean residual activity at a small fraction of the DCGL has a high probability ("power") of meeting the release criteria. Thus, it can be concluded that 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.

G. CHANGES IN INITIAL SURVEY UNIT ASSUMPTIONS ON EXTENT OF RESIDUAL ACTIVITY The survey was designed as a Class I land survey area; the FSS results were consistent with that classification. The direct measurement sample standard deviation was less than the design sigma. Thus, a sufficient number of sample measurements were taken and no additional measurements were required.

H. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit 6 was designed, performed, and evaluated in the June 2005 time frame. The design was performed to the criteria of the LTP Revision 4 (Reference 1). No subsequent LTP changes with potential impact to this survey unit need to be evaluated.

I. CONCLUSION The FSS of this survey unit was designed based on the designation as a Class I area. The survey design parameters are presented in Table 1. The required number of direct measurements was determined for the Sign Test in accordance with the LTP. As presented in Table 2, all direct measurements were less than the DCGLs of 4.2 pCi/g Cs-137 and 1.52 pCi/g Co-60. There were no investigations.

A Sign Test Summary analysis demonstrated that the Sign Test criteria were satisfied. The direct measurement sigma was determined to be less than that used for design, thus indicating that a sufficient number of samples was taken.

The Retrospective Power Curve shown in Attachment 4 confirmed that sufficient samples were taken to support rejection of the null hypothesis, providing high confidence that the survey unit satisfied the release criteria and the data quality objectives were met. Attachment 4 also revealed that direct measurement data represented essentially a log-normal distribution with one outlier.

FR-0200-06, Revision 0 Page 6 of 21

The scan survey design for this survey unit was developed in accordance with the LTP Revision 4 (Reference 1) with significant aspects of the design discussed in Section B and Table 1. ISOCS scans performed in a systematic grid pattern throughout the survey unit did not identify activity above the scan investigation levels of 1.0 pCi/g Cs-I 37 and 0.36 pCi/g Co-60. Therefore, no investigations were required as a result of the scan process.

It is concluded that FR-0200 Survey Unit 6 meets the release criteria of I OCFR20.1402 and the State of Maine enhanced criteria.

J. REFERENCES

1. Maine Yankee License Termination Plan, Revision 4, February 28, 2005 provided by Maine Yankee letter to the NRC, MN-05-010

2. Maine Yankee Procedure PMP 6.7.8, FSS Data Processing and Reporting, Attachment E, Approach for Dealing With Background Radioactivity for Maine Yankee Final Status Surveys

3. Maine Yankee Calculation No. EC-003-04, Use of Canberra In Situ Object Counting System (ISOCS) for FSS Surveys FR-0200-06, Revision 0 Page 7 of 21

Attachment 1 Survey Unit Maps FR-0200-06, Revision 0 Page 8 of 21

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Maine Yankee Map ID #: FRO200-6 REF Decommissioning Team Aintie Yatntkee DeconnimssioninhgProjectSurvey Forit IDate: 6/11/05 Survey Type: E Characterization Cl Turnover C Final Status Survey I Survey Area Name: Yard East Final Status Survey FRO200 SU6 Reference Map

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! < FROIII t-j u FRO200 SU6 Total Survey Unit Area = 1907 sq-m FR-0200-06, Revision 0 Page IOof 21

Maine Yankee Map ID#:FRO200-6a Decommissioning Team IMaine Yankee DeconnnissioningProjectSurvey ForiIDate: 5/04/05 Survey Type: O Characterization El Turnover 1 Final Status Survey Survey Area Name: RCA Yard East Soils Final Status Survey FRO200 SU6: RCA Yard East Soils ISOCS Scans S001 - S092 E

Typical ISOCS Spacing (MaXImum)

FR-0200-06, Revision 0 Page IIof 21

Maine Yankee Map ID #:FRO200-6b Decommissioning Team M Aainie Yankee Decommissioning Project Survey Formt IDate: 5104/05 Survey Type: O Characterization E Turnover CK Final Status Survey Survey Area Name: RCA Yard East Soils Final Status Survey FRO200 SU6: RCA Yard East Soils Direct Points S001 - S040 I,

C 624,OfS, 4'07'71S 6.r-Surface Area = 1907 sq-m N = 40 L= 6.9m FR-0200-06, Revision 0 Page 12 of 21

MMaine Yankee M Y D P Map ID#: FRO200-6C Decommissioning Team Afaite Yankee DecommissionitigProectSne ForIm IDate: 5117/05 Survey Type: [l Characterization E Turnover 1 Final Status Survey lSurvey Area Name: RCA Yard East Soils Final Status Survey FRO200 SU6: RCA Yard East Soils ISOCS Scans S093 - S102 z2 z~

FR-0200-06, Revision 0 Page 13 of 21

Attachment 2 Survey Unit Instrumentation FR-0200-06, Revision 0 Page 14 of 21

TABLE 2-1 INSTRUMENT INFORMATION ISOCS Detectors (Field Measurements)

Detector No. MDC (pCi/g) 7605 0.11 to 0.35 7607 0.17 to 0.36 7722 0.12 to 0.32 7780 0.15 to 0.33 HPGe Detectors (Laboratory Analysis)

Detector No. MDC (pCi/g)

FSSI 0.05 to 0.07 FSS2 0.04 to 0.07 TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, INVESTIGATION LEVEL AND DCGLENIC Parameter Instrument: ISOCS Comments Scan MDC 0.14 to 0.36 pCi/g Cs-137 - 16% DCGL

_____ _____ _____ 0.11I to_0.24_pCi/gCo-60 _ _ _ _ _ _ _ _ _ _ _

4.2 pCi/g Cs-137 Approved DCGL for land DCGL areas outside the Restricted 1.52 pCi/g Co-60 Area (Reference 1)

Investigation Level 1.0 pCi/g Cs-137 (Reference 3) I (ISOCS @ 3 m) 0.36 pCi/g Co-60 6.4 pC*/g Cs-I37 DCGL x Area Factor for Design DCGLEMC 2.3 pCi/g Co-60 Class 1 survey unit, per 2.3 pi/g o-60 LT`P Section 5.6.3 FR-0200-06, Revision 0 Page 15 of 21

Attachment 3 Investigation Table (No Investigations Required)

FR-0200-06, Revision 0 Page 16 of 21

Attachment 4 Statistical Data FR-0200-06, Revision 0 Page 17 of 21

Survey Package FRO200 Unit 6 UNITY Soil Sign Test Summary i 3-i*-,>iaut lum inpt ~<I' O'<-\-

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Survey Package: FRO200 Survey Unit: 06 Evaluator: Andy Olsen DCGL,: 1.OOE+00 Unity DCGL,,,: 1.50E+00 AF = 1.5 LBGR: 5.00E-01 Sigma: 3.17E-01 (1.33 pCi/g /4.2 pCi/g)

Type I error: 0.05 Type II error: 0.05 Nuclide: UNITY Soil Type: N/A

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io r- rns ei *sa 1.645 1.645 Sign p: 0.933193 Calculated Relative Shift: 1.5 Relative Shift Used: 1.5 Uses 3.0 if Relative Shift is >3 N-Value: 15 N-Value+20%: 18 Number of Samples: 40 Median: 4.90E-02 Mean: 5.30E-02 Net Sample Standard Deviation: 2.50E-02 Total Standard Deviation: 2.50E-02 Sum of samples and reference Maximum: 2.01E-01

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>iYl o;cmets Adjusted N Value: 40 S+ Value: 40 Critical Value: 25 Sign test results: Pass Sufficient samples collected: Pass Maximum value <DCGLw: Pass Median value <DCGL,: Pass Mean value <DCGLw: Pass Maximum value <DCGLemc: Pass Total Standard Deviation <=Sigma: Pass Criteria comparison results: .Pass_

The survey unit passes all conditions:l Pass Survey Unit Passes FRO200-SU6-Soil~ign-UNITY~xs 6/19105 6:37 PM FR-0200-06, Revision 0 Page 18 of 21

FRO200 SU-6 Quantile Plot 0.25 am N

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One-Sample T-Test Report Page/Date/Time 2 6/20/05 5:34:41 AM Database Variable C2 Plots Section Histogram of FR-0200, SU-6 35, CL 26-E a) o 18-4)

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0.000 . 60.63 ' 0.125 0.188 0.250 Activity (unitized)

FR-0200-06, Revision 0 Page 20 of 21

One-Sample T-Test Power Analysis Page/Date/Time 2 6/20/05 5:35:31 AM Chart Section Retrospective Power Curve 1.0-. .- .-.. - -

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0. 0 0.2 0.4 0.6 0.8 1.0 Survey Unit Mean (unitized)

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