ML043290285

Final Status Survey Release Record FA-1900 Heating & Ventilation 7 & 9 Area Footprint Survey Unit 1

ML043290285
Person / Time
Site:	Maine Yankee
Issue date:	11/17/2004
From:	Randall D Maine Yankee Atomic Power Co
To:	NRC/FSME
References
FA-1900-01, Rev 0
Download: ML043290285 (18)

Text

I MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FA-1900 HEATING & VENTILATION 7 & 9 AREA FOOTPRINT SURVEY UNIT 1 Prepared By: , e5l-) ) Date: //-/(-Ot(

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MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FA-1900 HV 7 & 9, AREA FOOTPRINT SURVEY UNIT I A. SURVEY UNIT DESCRIPTION Survey Unit I is located in Survey Area FA-1 900, the HV-7, 9 Area Footprint. HV-7, 9 was the heating and ventilation building located in the restricted area between the Containment Building and the Spray Building at site coordinates 407500 N and 623780 E. The HV-7, 9 Area is shown in relation to other major site structures in map FA 1900-01. All maps referenced in this release record are provided in Attachment 1, unless otherwise noted.

Survey Unit I consisted of the ventilation building footprint. The building was removed to Elevation 17' leaving the area with exposed rock ledge, a gravel/soil mixture, and some concrete foundation remnants. The survey unit has a surface area of approximately 101.4 in2 .

B. SURVEY UNIT DESIGN INFORMATION The HV-7/9 area was known to have been contaminated to levels in excess of the release limits during plant operation. Given the high probability of residual contamination, the survey unit was designated a Class I survey unit per the LTP.1 The survey unit design parameters are shown in Table 1. Given a relative shift of 1.4, it was determined that 20 direct measurements were required for the Sign Test. Each sample location was determined using a fixed square grid with a random start point. These locations are presented on survey map FA 1900-01a (Attachment 1). Direct measurements consisted of soil samples obtained at the required locations. The samples are analyzed with laboratory gamma spectroscopy.

The survey was also designed to include 6 scan grids each of approximately 50 in2 area. The scans were performed using in situ gamma spectroscopy (ISOCS) with the evaluation criteria set below the DCGL, as shown in Table 2-2 (Attachment 2). The scan locations are shown on map TA 1900-02 (Attachment 1).

The instruments used in this survey unit 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 also compared to the DCGL, the investigation level, and the DCGLEMC. As shown in this table, the scan MDC is less than the investigation criteria in all cases.

The survey unit could have been classified as a Class 2 survey unit in accordance with LTP Section 5.2.3. The higher classification was chosen for conservatism.

FA-1900-01, Revision 0 Page 2 of 18

TABLE 1 SURVEY UNIT DESIGN PARAMETERS Survey Unit J Design Criteria Basis Area 101.4 m' Section 5, LTP Based on an LBGR2 of 0.478 Number of Direct 20 pCi/g, sigma 3 of 1.33 pCi/g, Measurements Required and a relative shift of 1.4.

Type I = Type II = 0.05 Sample Area 5.07 m2 101.4 m' /20 samples Sample Grid Spacing 2.25 m (5.07)-2 Scan Grid Area - 50 m2 ISOCS field of view Area Factor 3.7 5.07 m' per LTP, Rev. 3 Scan Survey Area* - 101.4 mr 100% required B ackground e,______________^ _.' _____

N/A ISOCS used Scan Investigation Level 35% DCGL See Table 2-2 (Attachment 2)

DCGL 2.39 pCi/g LTP, Rev. 3 Design DCGLEN1C 8.84 pCi/g LTP, Rev. 3

• NOTE: ISOCS scans had significant overlap causing scan area to exceed 100%.

C. SURVEY RESULTS Twenty direct measurements were made in Survey Unit 1. All direct measurements were less than the DCGL. Direct measurement data are presented in Table 2. Scanning resulted in no measurements above the investigation level. Therefore, no investigations were required.

2 The LBGR was based on an assumed survey unit mean activity of 20% of the DCGL.

3 Sub-slab soil contamination was assumed to be consistent with surrounding soil. Sigma taken from LTP Table 5-1 C, ROI00, RCA Yard West.

FA-1900-01, Revision 0 Page 3 of 18

TABLE 2 DIRECT MEASUREMENTS Sample Number Cs-137 (pCi/g) Co-60 (pCi/g) Unitized Values FAI900-1-SOO1 2.11E+00 + 1.31E-01 4.27E-02 + 1.05E-02 0.932 FA1900-1-S002 1.06E+00 + 7.73E-02 5.99E-02 + 1.15E-02 0.513 FAI900-1-S003 5.95E-01 + 4.39E-02 1.84E-02 + 1.78E-02 0.270 FA1900-1-S004 2.08E-01 +2.51 E-02 4.11E-02 + 1.93E-02 0.135 FA1900-1-S005 1.36E+00 + 8.81E-02 3.38E-02 + 9.99E-03 0.608 FA1900-1-S006 6.78E-01 + 5.24E-02 6.85E-02 + 1.22E-02 0.364 FAI900-1-S007 1.18E-01 + 2.29E-02 2.12E-02 + 8.70E-03 0.074 FAI900-1-S008 2.30E-01 +2.46E-02 9.06E-02 + 1.40E-02 0.201 FAI900-1-S009 2.70E-02 + 1.16E-02 2.07E-02 + 1.72E-02 0.035 FA1900-1-S010 4.55E-02 + 1.60E-02 2.34E-02 + 1.76E-02 0.046 FA1900-1-S01 1 4.04E-02 + 9.24E-03 3.11E-02 + 1.31E-02 0.053 FA1900-1-S012 <1.1413-01 <1.32E-01 0.201 FAI900-1-S013 3.22E-02 + 8.13E-03 < 2.95E-02 0.048 FAI900-1-S014 <1.38E-01 <1.37E-01 0.217 FA1900-l-S015 3.95E-02 + 1.51E-02 1.12E-01 + 1.38E-02 0.147 FAI900-1-S016 <1.15E-01 <1.26E-01 0.195 FAI900-1-S017 <9.65E-02 <1.07E-01 0.165 FAI900-1-S018 2.38E-02 + 1.14E-02 1.96E-02 + 1.27E-03 0.033 FA1900-1-S019 4.87E-02 + 1.41E-02 3.33E-02 + 1.08E-02 0.059 FAI900-1-S020 <1.26E-01 <1;44E-01 0.220 Mean 3.60E-01 6.46E-02 2.26E-01 Median 1.17E-01 4.19E-02 1.80E-01 Standard 5.54E-01 4.57E-02 2.28E-01 Deviation I Range 2.38E-02 -2.11E+00 1.84E-02 - 1.44E-O1 - 3.28E-02-9.32E-01 NOTE: Bold values indicate nuclides positively detected, "<" indicates MDA values.

D. SURVEY UNIT INVESTIGATIONS PERFORMED AND RESULTS The scan process identified no locations of potentially elevated activity. Therefore, no investigations were performned.

FA-1 900-01, Revision 0 Page 4 of 18

E. SURVEY UNIT DATA ASSESSMENT An analysis of the direct sample measurement results, including the mean, median, standard deviation, and sample range, are provided in Table 2. The direct measurements were all below the unitized DCGL. The maximum result is equivalent to a unity fraction of 0.932.

When adjusted for background (disturbed soil fallout Cs-1 37 of 0.19 pCi/g), the mean unitized residual contamination level (net Cs-137 activity plus Co-60 unitized activity) is 0.147. This is equivalent to an annual dose rate of 0.8264 mrem/y.

No scan measurements exceeded the investigation criteria and no investigations were performed.

F. ADDITIONAL DATA EVALUATION Attachment 4 provides additional data evaluation associated with Survey Unit I, 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.

I. The Sign Test Summary provides an overall summary of design input 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. As shown in the table, all of the key release criteria were clearly satisfied for FSS of this survey unit.

2. The Quantile Plot was generated from direct measurement data listed in Table 2 and indicates general symmetry about the median. The data set and plot are consistent with expectations for a Class I survey unit. There is no reason to conclude that the data set represents other than random variations in a Class I survey unit. It also should be noted that the maximum unitized activity (0.932 at location S001) is less than the unitized DCGL of 1.0.

3. A histogram plot was also developed on the direct measurement values. This plot shows that the direct data were essentially a log-normal distribution with 4 outliers.

4. A Retrospective Power Curve was constructed based on FSS results. The curve shows that the 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.

4 The annual dose equivalent was determined by multiplying the unitized net soil activity by 5.63 (the annual dose equivalent for surface soil) mrem.

FA-1900-01, Revision 0 Page 5 of 18

G. CHANGES IN INITIAL SURVEY UNIT ASSUMPTIONS ON EXTENT OF RESIDUAL ACTIVITY The survey was designed as a Class I area; the results were consistent with that classification. The post-remediation direct measurement sample standard deviation was less than the design sigma. The actual survey unit mean was slightly larger than the design LBGR. This has no impact on the survey design since the relative shift would be greater than 1.4 if the actual sigma was used. Thus, a sufficient number of sample measurements were taken.

II. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit I was designed and performed using the criteria of the approved LTP (Revision 3 Addenda). The only subsequent LTP changes (with potential impact to this FSS) were provided in the proposed license amendment related to modifications of the activated concrete remediation plan submitted September 11, 2003 (Reference 4). Changes represented in this later proposed license amendment have been evaluated and have no impact on the design, conduct, or assessment of the final status survey of Survey Unit 1.

1. CONCLUSION The FSS of this survey unit was designed based on the LTP designation as a Class I area.

The survey design parameters are presented in Table 1. The required number of direct measurements wvas determined for the Sign Test in accordance with the LTP. As presented in Table 2, all direct measurements were less than the unitized DCGL of 1.0.

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 were 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 variance consistent with expectations for a Class 1 survey unit.

The scan survey design for this survey unit was developed using in situ gamma spectroscopy with significant aspects of the design discussed in Section B and Table 1. The scan coverage was greater than 100% of the survey unit. No investigations were required.

It is concluded that FA-1900 Survey Unit 1 meets the release criteria of IOCFR20.1402 and the State of Maine enhanced criteria.

J. REFERENCES

1. Maine Yankee License Termnination Plan, Revision 3, October 15, 2002

2. Maine Yankee letter to the NRC, MN-02-061, dated November 26, 2002

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

4. Maine Yankee letter to the NRC, MN-03-049, dated September 11, 2003 FA-1900-01, Revision 0 Page 6 of 18

Attachment I Survey Unit Maps FA-1900-01, Revision 0 Page 7 of 18

Maine Yankee DecommLssionln Team I AMaine YankeeDecommissiorninzgProjectSurveyMap Map IMaplD#FA1900-01 Survey Type: j;-- Veriricaiion XJ Turnaver ,-!Final Status Survey Survey Area Name: HV 7&9 Footprint 623,700 E 623,800 E 623,900 E 624,000 E 624,100 E

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econmmssioanimTeam I lMaine Yankee DecommissioningProject Survey Map I MapID FA 1 900-01a Survey Tpe: Verification Turnover Final Status Survey Survey Area Name: HV 7&9 Sub Slab Footprint Sample Points

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R003 FA-1900-01, Revision 0 Overlapping Scan Area Page 10 of 18 I

Attachment 2 Survey Unit Instrumentation FA-1900-01, Revision 0 Page 11 of 18

TABLE 2-1 INSTRUMENT INFORMATION lIPGe Detectors for In Situ Gamma Spectroscopy I ISOCS SIN I Probe S/N (type)

[1 7607 l N/A IIPGe Detectors for Lab Analysis of Volumetric Samples I Detector Number I MDC (PCi/g)

FSS-I - 0.1 Cs-137 and Co-60 FSS-2 - 0.1 Cs-137 and Co-60 l_DET 2 - 0.15 Cs- 37 and Co-60 DET 3 - 0.15 Cs-137 and Co-60 TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, INVESTIGATION LEVEL, AND DESIGN DCGLENIC l Detector J ISOCS Scan MDC0.31 pCi/g Cs-137 Scan MDC 0. 17 pCi/g Co-60 DCGL 2.39 pCi/g Cs-137 0.86 pCi/g Co-60 Investigation Level 35% DCGL Design DCGLEcTC 8.84 pCi/g Cs-137 From Release Record Table 1 8.4pig sI3 FA-1900-01, Revision 0 Page 12 of 18

Attachment 3 Investigation Table (No investigations required)

FA-1900-01, Revision 0 Page 13 of 18

Attachment 4 Statistical Data FA-1900-01, Revision 0 Page 14 of 18

Survey Package FA-1900 Unit 1 UNITY Soil Sign Test Summary 5.d., iEInput

.'atlon Values rn'm' '

Survey Package: FA-1900 HV-7,9 Footprint Survey Unit: 01 Evaluator: GP DCGL,: 1.OOE+00 DCGL,.: 3.70E+00 LBGR: 2.OOE-01 Sigma: 5.56E-01 Unitized Type I error: 0.05 Type II error: 0.05 Nuclide: UNITY Soil Type: N/A X ?ff ~i;<-~-'4,';.-A iC' ci ~u 3/4i85......... i~ated ~ au ,; rs ; t _ -_ - _! _ _ _ _ _ _ _ _ _ _v _ _ _ _ _ _ _ _ _ _ _

1.645 1.645 Sign p: :0.919243 Calculated Relative Shift: 1.4 Relative Shift Used: 1.4 Uses 3.0 if Relative Shift is >3 N-Value: 16 N-Value+20%: 20 it + e~~- 7Sa..-s-;h-4Z .rple .g ,_/ol Data afues i.-i:*z}

Number of Samples: ;. 20 Median: 1.80E-01 Mean: 2.26E-01 Net Sample Standard Deviation: 2.28E-01 Total Standard Deviation: 2.28E-01 SRSS Maximum: 9.32E-01

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Adjusted N Value: 20 S+ Value: i 20 Critical Value: ;14 Sign test results: I Pass Sufficient samples collected: Pass Maximum value <DCGLw: Pass Median value <DCGLw: Pass Mean value <DCGL: . Pass Maximum value <DCGL,,,: Pass Total Standard Deviation <=Sigma: -Pass Criteria comparison results: b . Pass The sFuilv'uiatp c i_: .',,'- 1>E

-L ePm The survey unit passes all conditions:l J-N-4 Pass__________________

FA-1900-SUl-SoilSIgn-UNITY 10127/04 12:24 PM FA-1900-01, Revision 0 Page 15 of 18

FA-1900 SU-1 Quantile Plot I

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One-Sample T-Test Report Page/Date/Time 2 10/14/04 10:13:42 AM Database C:\Program Files\NCSS97\FA1900 SU-1.S0 Variable C2 Plots Section Histogram of FA-1900, SU-i 0.

E Y) to 20 C,

E z3 Activity (Unitized)

FA-1900-01, Revision 0 Page 17 of 18

One-Sample T-Test Power Analysis Page/Date/Time 2 10/14104 10:15:17 AM Chart Section Retrospective Power Curve 1.0 0.8 ---

0 . - - - - - - - - - - - - - - - - - -

0.6 0.4 0s 0 0.2-.-- * -;- IX SuvyUi Mea (Uity)

0. I I I I 0.2 0.4 0.6 0.8 1.0 1.2 Survey Unit Mean (Unity)

FA-1900-0I, Revision 0 Page 18 of 18