ML050590111

Final Status Survey Release Record FR-0900 Balance of Plant Areas Survey Unit 3

ML050590111
Person / Time
Site:	Maine Yankee
Issue date:	02/17/2005
From:	Donna Anderson, Dockins L, Madison G, Packer J, Pillsbury G Maine Yankee Atomic Power Co
To:	Document Control Desk, NRC/FSME
References
FR-0900-03, Rev 0
Download: ML050590111 (19)

Text

MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0900 BALANCE OF PLANT AREAS SURVEY UNIT 3 Prepared By: __ Date:  ?/* /

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MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0900 BALANCE OF PLANT AREAS SURVEY UNIT 3 A. SURVEY UNIT DESCRIPTION Survey Unit 3 is located in Survey Area FR-0900 in the buffer area adjacent to the Restricted Area (RA) west of FR-0I 1I SU9 and southwest of FR-0I 00 SUl . It is approximately bounded by407,380N/623,680E, 407,410N/623,540E and 407 710N/623,600E using Maine State Coordinate System (West Zone) NAD 1927. This 282 mi Class 2 Survey Unit is a 2-meter wide buffer area (strip) between the Class I RA Backyard and the adjacent Class 3 open land area. Since this area resides adjacent to Class I areas with extensive remediation histories, its classification was increased from Class 3 to Class 2. The increase in classification provides higher confidence that remediation efforts in adjacent Class I areas or past plant operations did not impact the survey unit. The location of the survey unit in relation to the restricted area is shown on map FRO900U3-SITE (Attachment 1).

B. SURVEY UNIT DESIGN INFORMATION Survey Unit 3 met the LTP Revision 3 definition for a Class 3 survey unit, however, was reclassified as a Class 2 survey unit from a history of enhanced materials (elevated Cs-I 37 activity exceeding natural fallout levels) from MY operations and its proximity adjacent to Class 1 areas with extensive remediation histories. The survey unit design parameters are shown in Table 1. Given a relative shift of 1.5, it was determined that 18 direct measurements were required for the Sign Test. Because the measurement locations were based on a systematic square grid with a random start point, the N=1 8 design led to a survey unit map with 19 locations which are illustrated on map FR0900U3-DIRT (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 10-100% of the 282 m2 area were required for the Class 2 survey unit. This was accomplished by use of an in sitll gamma spectroscopy detector (ISOCS) configured at a 2-meter distance from the surface to obtain overlapping 12-m 2 fields of view. The ISOCS detector was positioned perpendicular to the surface.

Locations of the 48 survey scans are shown on map FRO90OU3-SCAN.

The ISOCS scans were configured to ensure 100% scan coverage of all exposed surfaces within Survey Unit 3. Some small areas were obscured with rocks, trees, or brush.

However, the affected areas represented a small fraction of the total scan area and are therefore judged to be acceptable. 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 and the investigation level. The scan MDC is less than the scan investigation level, thus providing high confidence that an elevated area would be detected in the scanning process.

FR-0900-03, Revision 0 Page 2 of 19

TABLE I SURVEY UNIT DESIGN PARAMETERS Surey Unit Design Critcria Basis Area 282m 2 Class 2, < 10,000 m2 Based on an LBGR of 2.1 pCi/g, Number of Direct 18 sigma1 of 1.33 pCi/g, and a relative Measurements Required shift of 1.5.

Type I = Type 1I = 0.05 Sample Area 15.6 m2 282 m2/ 18 = 15.6 m2 Sample Grid Spacing 3.9 m (15.6)112 Scan Grid Area ISOCS scan at 2-meters See Section B Area Factor NA Only required for Class I areas Scan Area 282 m2 Class 2 Area- 10-100%

1.0 pCi/g Cs-l 37 ISOCS investigation levels with Scan Investigation Level 0.36 pCi/g Co-60 detector at 2-meter height

______2____________37 (Reference 6)

DCGL 1.52 pC i/g Co-630 References 4 and 7 C. SURVEY RESULTS A total of 19 direct measurements were performed in Survey Unit 3. Fourteen samples contained Cs-I 37 with levels of residual activity below the DCGL. No samples identified Co-60. An evaluation was performed on one sample with low sample net weight (- 795 grams) and determined to have no significant impact on the original data. No investigations were needed based on the direct measurement results since all measurements were below the DCGL.

ISOCS gamma scans were performed at 48 locations using an investigation level of 1.0 pCi/g Cs-137 and 0.36 pCi/g Co-60 which was conservative for the 2 m detector height when compared to typical investigation levels of 2.2 pCi/g Cs-137 and 0.80 pCilg Co-60. The lower investigation levels were used because Co-60 was not expected in the survey unit. The gamma scans were performed for a sufficient count time to achieve a Minimum Detectable Activity (MDA) of approximately 15% of the DCGL. Scan investigation levels were conservatively set at approximately 25% of the DCGL. All scan activity values were below the investigation levels. There were no positive detection results for Co-60. An evaluation was performed to determine the effect of 1 inch of water attenuation on the survey results with no significant impact found on the original data. Therefore, no investigation surveys were performed as a result of the scan surveys.

LTP Revision 3, Table 5-1C for RCA Yard West, RO 100 FR-0900-03, Revision 0 Page 3 of 19

TABLE 2 DIRECT MEASUREMENTS Cs-137 Uncertainty Sample Number (PCilg) (pCi/g)

FR0900032S001 < 3.79E-02 FR0900032S002 < 4.04E-02 FR0900032S003 1.08E+00 1.1lE-01 FR0900032S004 4.87E-01 6.37E-02 FR0900032S005 5.50E-01 6.52E-02 FR0900032S006 5.86E-01 7.52E-02 FR0900032S007 6.49E-01 6.92E-02 FR0900032S008 1.04E+00 1.23E-01 FR0900032S009 1.44E-01 3.31 E-02 FR0900032S010 1.73E-01 4.35E-02 FR0900032S01 I 4.17E-01 6.26E-02 FR0900032S012 3.71E-01 6.73E-02 FR0900032S013 3.79E-01 5.47E-02 FR0900032S014 1.10E-01 3.98E-02 FR0900032S015 3.40E-01 4.88E-02 FR0900032S016 < 9.24E-02 FR0900032S017 < 4.97E-02 FR0900032S018 2.02E-01 3.57E-02 FR0900032S019 < 4.12E-02 Mean 3.57E-01 Median 3.40E-01 Standard Deviation 3.18 E-01 Range 3.79E-02 to 1.08E+00

"<" indicates MDA value. Bold indicates positive detection value. No Co-60 was detected above MDA.

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

FR-0900-03, Revision 0 Page 4 of 19

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 19 soil samples collected, 14 identified Cs-1 37 activity below the DCGL value of 4.2 pCi/g. All other values were below the MDA. Identified sample activities or Minimum Detectable Activities are listed in Table 2. No Co-60 was detected above MDA. The mean and median activities 'were less than the DCGL for Cs-137.

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-1 37 value (0.19 pCi/g) 2 for disturbed soil from the survey unit sample mean activity (0.357 pCi/g). This would equate to an annual dose rate of 0.40 mrem/year 3 .

Also, for purposes of demonstrating compliance with the radiological criteria for license termination and the State of Maine enhanced 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 informnation. Based on survey unit direct measurement data, this attachment provides the Sign Test Summary, Quantile Plot, Histogram, and Retrospective Power Curve.

I. The Sign Test Summary provides an overall summary of design input (Table I) 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. As discussed in Section E, 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. The Quantile Plot was generated from the Cs-137 activity data listed in Table 2. Ile data set and plot are consistent with expectations for a Class 2 survey unit. All of the measurements are below the DCGL of 4.2 pCi/g for Cs-137 for land outside the restricted area. The two outliers for Cs-137 vere approximately 25% of the DCGL, and associated ISOCS 12 m2 scans of the area positively identified Cs-137. The two outliers were still within the distribution range of background Cs-137 soil levels found in the background reference area survey for undisturbed soil (Reference 8). The majority of this area is undisturbed soil.

2 See Attachment E to Maine Yankee Procedure PMP 6.7.8 (Reference 5).

3 This annual dose equivalent is based on LTP Section 6.7 which shows the areas outside the RA contaminated soil contribution (for soils contaminated at the DCGL) to be 10 mremly. Therefore, the annual dose rate would equate to Annual Dose Rate = 10 x (- 42.1*) =O.4Omremly FR-0900-03, Revision 0 Page 5 of 19

3. A Histogram Plot was also developed based on the Cs-137 activity values. This plot shows a log normal distribution with two outliers.

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 2 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.

HI. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit 3 was designed, performed, and evaluated in January and February 2005. The design was performed to the criteria of the LTP Revision 3 (References 2 and 4).

LTP Change No.05-001 (Reference 7) modified the Table 6-11, "Contaminated Material DCGL," to reflect an increased Deep Soil DCGL of 0.86 pCi/g for Co-60 for areas in the RA.

This change has no effect on the survey for FR-0900 Survey Unit 3. No subsequent LTP changes with potential impact to this survey unit need to be evaluated.

1. CONCLUSION The FSS of this survey unit was designed as a Class 2 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-I 37.

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 two outliers.

FR-0900-03, Revision 0 Page 6 of 19

The scan survey design for this survey unit was developed in accordance with the LTP Revision 3 Addenda (References 2 and 4) with significant aspects of the design discussed in Section B and Table 1. ISOCS scans performed at a distance of 2 meters in a systematic grid pattern throughout the survey unit did not identify activity above the scan investigation levels of 1.0 pCi/g Cs-1 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-0900 Survey Unit 3 meets the release criteria of I OCFR20.1402 and the State of Maine enhanced criteria.

J. REFERENCES

1. Maine Yankee License Termination Plan, Revision 3, October 15,2002 and Addenda provided by Maine Yankee letter to the NRC, MN-02-061, dated November 26, 2002

2. NRC letter to Maine Yankee, dated February 28, 2003

3. Maine Yankee letter to the NRC, MN-03-049, dated September 11, 2003 (LTP Supplement to LTP Revision 3)

4. Issuance of License Amendment No. 170, NRC letter to Maine Yankee, dated February 18, 2004

5. 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

6. Maine Yankee Calculation No. EC-003-04, Use of Canberra In Situ Object Counting System (ISOCS) for FSS Surveys

7. Maine Yankee LTP Change Number 05-001, Deep Soil Co-60 DCGL

8. FR-9800 Background Reference Area Soil Survey Unit I FR-0900-03, Revision 0 Page 7 of 19

Attachment I Survey Unit Maps FR-0900-03, Revision 0 Page 8 of 19

colmnnissioning Teom Maine Yankee Decommissioning Project SurveyMap I DnFlA 9OUITE Survey Type: ] Characterization [] Turnover

• Final Status Survey I SurveyArea Name: Site Location IPreporeds:y Larry N. Dockins Date: 1/1 7/05 407,300 N 407,400 N 407,500 N 407,600 N 407,700 N

. 407,800 N a.I

.407,900 N FR-0900-03, Revision 0 Page 9 of 19

DcoMmnssYnO l Maine Yankee Decommnissioning Project Survey Map I 0 Survey Type: EJ Charocferlation [ Turnover a rinol status Survey I SurveyAreaNarne: Direct Locations

_Prepared Byr Larry N. Dockins Date: 1/1 7/05 FR-0900-03, Revision 0 II I I I I I II I I I l I Page 10 of 19 0 50Om

Maine Yankee Maine YankeeDecommissioningProject Surveyap M apID#FRO900U3-SCAN Survey Type: [] Characterization [] Turnover

• Final Status Survey I SurveyAreaName: Scan Locations IPreparedBy. Larry N. Dockins Date: 1/17/05 z K z

_n Typ Suv.

Typ C Survey Unit Boundary ISOCS Typical Configuration _

FR-0900-03, Revision 0 Page 11 of 19

Attachment 2 Survey Unit Instrumentation FR-0900-03, Revision 0 Page 12 of 19

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

Detector No. MDC (pCi/g) 7780 ( 0.14 to 0.42 lIPGe Detectors (Laboratory Analysis)

Detector No. MDC (pCi/g)

FSS1 0.04 to 0.11 FSS2 0.04 to 0.07 TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, AND INVESTIGATION LEVEL Parameters Instrument: ISOCS Comments Scan MDC 0.14 to 0.42 pCi/g Cs-137 - 15% DCGL

_______________0. 15 to_0.24_pCi/gCo-60 Approved DCGL for DCGL 4.2 pCi/g Cs-137 land areas outside the 1.52 pCi/g Co-60 Restricted Area, (References 4 and 7)

Investigation Level 1.0 pCi/g Cs-137 (ISOCS Oa, 2 m) 0.36 pCi/g Co-60 (Reference 6)

FR-0900-03, Revision 0 Page 13 of 19

Attachment 3 Investigation Table (There were no investigations)

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Attachment 4 Statistical Data FR-0900-03, Revision 0 Page 15 of 19

Survey Package FRO900 Unit 3 CS-137 Soil Sign Test Summary

• ' < V.

jEaluation InputValiuet slr4: io';Cmm nt'sif*-'

Survey Package: FRO900 Balance of Plant Areas Survey Unit: 03 Evaluator: G. Madison DCGLw: 4.20E+00 Cs-137 DCGL DCGL,,,: 4.20E+00 LBGR: 2.1OE+00 50% of DCGL Sigma: 1.33E+00 LTP Rev 3, Table 5-1 C for RCA Yard West Type I error: 0.05 Type II error: 0.05 Nuclide: CS-1 37 Soil Type: N/A_

Z.,,: 1.645 Zt-P- 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 4' ;SarnpSle Data s ia. a; '

Number of Samples: 19 Median: 3.40E-01 Mean: 3.57E-01 Net Sample Standard Deviation: 3.18E-01 Total Standard Deviation: 3.18E-01 Maximum: 1.08E+00 Xwr:~O 5 JSign> est Resuls o'tvg 2'f..-rfYtOnment d

Adjusted N Value: 19 S+ Value: 19 Critical Value:l 13 Sign test results: Pass

.:~~-- ~~ Crte rla Si tIs ~ _ __ _ _ __ _ _

Sufficient samples collected: Pass Maximum value <DCGL,: Pass Median value <DCGL,: Pass Mean value <DCGL.: Pass Maximum value <DCGL,,.: Pass N/A for Class 2 Total Standard Deviation <=Sigma: Pass_

Criteria comparison results: Pass Thesuveuitp con'di tions:j all . PasSuv Unme ntss---'

The survey unit passes allconditions:l Pass Survey Unit Passes FRO900-SU3-Soil~ign-CS-1 37 2)15105 10:45 AM FR-0900-03, Revision 0 Page 16 of 19

FR-0900 SU-3 Quantile Plot 1.20E+OO -r 1.OOE+OO In 8.OOE-01 c)

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u I* Activity (pCi/g) w 6.OOE-01 - 4-O x0

- Median (pCi/g),

A:

I' 0 To 4.OOE-01 *

• 2.OOE-01 O.OOE+OO 0 25 50 75 100 Percent

One-Sample T-Test Report Page/Date/Time 2 2/3/05 8:56:13 AM Database Variable C2 Plots Section Histogram of FR-0900, SU-3 0)

E co

~D E

z Activity (pCilg)

FR-0900-03, Revision 0 Page 18 of 19

One-Sample T-Test Power Analysis Page/Date/Time 2 2/3/05 8:58:07 AM Chart Section Retrospective Power Curve

1. 0 . . -. _ _ _--- -- - - - -

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0.4- -- - - - X-

. . I 0.2 . - --- ,

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0.0 I 1 1 0 1 2 3 Survey Unit Mean (pCilg)

FR-0900-03, Revision 0 Page 19 of 19