ML051050106
| ML051050106 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 03/31/2005 |
| From: | Ambrose J, Packer J, Pillsbury G, Randall D Maine Yankee Atomic Power Co |
| To: | NRC/FSME |
| References | |
| FR-0220-01, Rev 0 | |
| Download: ML051050106 (21) | |
Text
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0220 SPARE TRANSFOMER PAD FOOTPRINT SURVEY UNIT I Prepared By: , . 2Cf<
,, f Date: - 3 FSS Engineer - Signature b/Printed Name Reviewed By: ,M- h Date:______
pe1Sinecn e Signature Printed Name Reviewed By: 1W0" ( m, Date: Z-5 Independent Review - Signature Yriv;§ame Approved By: _ Date: /
) ,/_,perinten t Signature
/"'FSS, MOP - Signature Printed Name Revision 0
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0220 SPARE TRANSFORMER PAD FOOTPRINT SURVEY UNIT I A. SURVEY UNIT DESCRIPTION Survey area FR-0220 Survey Unit 1, Spare Transformer Pad Footprint, consists of the subsurface soils below the demolished spare transformer pad. The soil within this shallow excavation is a mix of native soils, gravel and ledge. The area is a near surface excavation with slight sloping that permitted accessibility. Survey Unit I is located around grid coordinates 407,450 N and 624,200 E using the Maine State Coordinate System (West Zone),
NAD 1927.
The survey unit area is shown in relation to other major site structures in map FR0220-01.
All maps referenced in this release record are provided in Attachment 1, unless otherwise noted. The survey unit total area is approximately 183 m 2 .
B. SURVEY UNIT DESIGN INFORMATION The area was designated a Class 3 land survey unit per the LTP (Table 5-1 C) for R0200 (Yard East). Since the survey unit was surrounded by FR-0200, the design sigma value for that area was applied. The survey unit design parameters are shown in Table 1. Given a relative shift of 3.0, it was determined that 14 direct measurements were required for the Sign Test. Measurement locations were randomly determined and are illustrated on map FR-0220-
- 02. All direct measurements consisted of soil samples obtained at the required locations.
The samples were analyzed with laboratory gamma spectroscopy.
Scan grids of 1 m by 1 m and I m by 2m were established as indicated on survey map FR-0220-03. A 1% to 10% scan coverage of the area was required. The 16 scan grids provided a total scan area of approximately 18 mi2 , meeting the scan requirement. The survey instruments used, their MDCs, and alarm setpoints are provided in Attachment 2.
Background values were established for the scan measurements based on local scaler values in the survey unit. These background values were used to establish scan alarm setpoints.
Due to variability in background between soil and ledge media within the survey unit, the grids were divided into two different background groups based on the predominant media at the scan grid location. Specific values are specified in Table 1.
FR-0220-01, Revision 0 Page 2 of 21
TABLE 1 SURVEY UNIT DESIGN PARAMETERS Survey Unit l Design Criteria Basis Area 183 m2 No limit for Class 3 Area Based on an adjusted LBGR of Number of Direct 14 3.69 pCi/g, sigma' of 0.17 Measurements Required pCi/g, and a relative shift of 3.0.
Type I= Type II= 0.05 Sample Area N/A Class 3 Area Sample Grid Spacing N/A Class 3 Area Scan Grid Area Im x Im and Im x2m Class 3 Area Area Factor N/A Class 3 Area Scan Survey Area 18 m2 Class 3 Area 1% - 10%
Background 7 4
SPA-3 (scan) 13,056 cpm Soil 13,744 cpm Ledge / Rock Scan Investigation Level 3 Sigma of Directed by then current Rev of ScanInvestigationLevel Background plus DCGL Procedure PMP 6.7.8 Rev (G)2 DCGL 4.2 pCi/g LTP Revision 3
__ _ __ _ _ __ __ __ (Reference 4)
Design DCGLEMNc N/AClass 3 Area C. SURVEY RESULTS As required, 14 direct soil measurements were made and the results are presented in Table 2.
All direct measurements were below the DCGL. One verified alarm was received during the scans. The investigation of the verified alarm is discussed below.
Design sigma based on LTP Revision 2, Table 5-IC, East Yard, FR-0200.
2 All changes with potential influence to the FSS results are evaluated in Section H.
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TABLE 2 DIRECT MEASUREMENTS Sample Number Cs-137 (pCilg)3 Uncertainty FR-0220-1-3-SOOI < 5.43E-02 N/A FR-0220-1-3-S002 < 5.87E-02 N/A FR-0220-1-3-S003 < 5.62E-02 N/A FR-0220-1-3-S004 < 5.70E-02 N/A FR-0220-1-3-S005 < 5.40E-02 N/A FR-0220-1-3-S006 < 6.12E-02 N/A FR-0220-1-3-S007 < 5.06E-02 N/A FR-0220-1-3-S008 < 6.14E-02 N/A FR-0220-1-3-S009 < 5.28E-02 N/A FR-0220-1-3-S010 < 5.50E-02 N/A FR-0220-1-3-SOI I < 5.33E-02 N/A FR-0220-1-3-S012 < 5.76E-02 N/A FR-0220-1-3-S013 < 5.80E-02 N/A FR-0220-1-3-S014 < 4.27E-02 N/A Mean 5.52E-02 __ __
Median 5.56E-02 Standard Deviation 4.75E-03 Range 4.27E-02 to 6.14E-02
"<" indicates values less than the MDA, MDA value is reported.
D. SURVEY UNIT INVESTIGATIONS PERFORMED AND RESULTS The scans identified one verified alarm location (scan grid 31) upon ledge. An investigation was conducted via survey investigation package XR0220-01. The investigation involved dividing the 1--m2 grid into nine equal area sub grids as shown on map XR0220-02. A scan
,was performed on each of the sub-grids. This process yielded five verified alarms. Each of these localized areas was then counted using the ExploraniumTM GR-130 to check the ledge for the presence of plant-derived nuclides.
All investigation results were less than MDA for Cs-137 and Co-60. The ExploraniumTm GR-130 MDAs were 0.423, and 1.16 pCi/g respectively (Reference 6). Investigation results are summarized in Attachment 3 (Table 3-1).
3 The samples were also analyzed for Co-60; all were less than an MDA of 0.1 pCi/g.
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E. SURVEY UNIT DATA ASSESSMENT An analysis of the direct sample measurement results, including the mean, median, standard deviation, and sample result range are provided in Table 2. Both the mean and median activities were less than the DCGL for Cs-i 37. The maximum direct measurement result was less than 1.5% of the Cs-137 DCGL. Further, since the activity is less than the action levels in LTP Table 5-7, no additional investigations or any reclassification is required.
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 established mean fallout Cs-137 background value (0.19 pCi/g per Reference 5) for disturbed soil from the survey unit sample mean activity (0.055 pCi/g). The result is a negative net activity value. This would equate to an annual dose rate of 0 mrem/y. However, for purposes of demonstrating compliance with the radiological criteria for license termination and the enhanced State criteria, background activity is not subtracted from the soil 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. As is shown in the table, all of the key release criteria were clearly satisfied for the FSS of this survey unit.
- 2. The Quantile Plot was generated from direct measurement data listed in Table 2. The data set and plot are consistent with expectations for a Class 3 survey unit. All of the measurements are well below the DCGL of 4.2 pCi/g.
- 3. A Histogram Plot was also developed based on the direct measurement values. This plot shows that the direct data were essentially a normal distribution.
- 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.
FR-0220-01, Revision 0 Page 5 of 21
G. CHANGES IN INITIAL SURVEY UNIT ASSUMPTIONS ON THlE EXTENT OF RESIDUAL ACTIVITY The survey was designed as a Class 3 area; the FSS results were consistent with that classification. The direct measurement sample total standard deviation was less than the design sigma, indicating that a sufficient number of sample measurements were taken.
H. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit I was designed and performed in the summer of 2002. The design was performed to the criteria of the LTP, Revision 2 (Reference 4). The following LTP changes and procedural changes with potential impact to this survey unit were evaluated and determined not to have an impact on the FSS results for this survey unit.
- 1. Requirement to check background + 1,000 cpm prior to scanning each grid (LTP Rev. 3 Addenda, 11-26-02).
- 3. Change in alarm setpoint methodology during the evolution of the use of E600 (use of scaler vs. peak values to establish the investigation level and deletion of the DCGL term).
- 4. LTP changes in the activated concrete license amendment (proposed in MY letter to the NRC, MN-03-049, 09/11/03).
- 5. The procedural commitment to the state of Maine of limiting grid size to 10 m2 (documented in MY letter to the NRC, MN-03-009, 2/26/03).
I. CONCLUSION The FSS of this survey unit was designed based on the LTP designation as a Class 3 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 50% of the DCGL of 4.2 pCi/g (Cs-137).
A Sign Test Summary analysis demonstrated that the Sign Test criteria were satisfied. The direct measurement sigma was less than that used for design so no additional samples were required.
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 normal distribution, with variance consistent with expectations for a Class 3 survey unit.
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The scan survey design for this survey unit was developed in accordance with the LTP with significant aspects of the design discussed in Section B and Table 1. Scanning resulted in one verified alarm for evaluation. Attachment 3 shows the areas identified by verified alarms and provides the results, all of which were less than DCGL.
It is concluded that FR-0220 Survey Unit I meets the release criteria of 10CFR20.1402 and the State of Maine enhanced criteria.
J. REFERENCES
- 1. Maine Yankee Engineering Calculation, EC-009-01
- 2. Maine Yankee License Termination Plan, Revision 3 issued October 15, 2002
- 3. Maine Yankee letter to the NRC, MN-02-061, dated November 26, 2002
- 4. Maine Yankee License Termination Plan, Revision 2, issued August 13, 2002
- 5. Approach for Dealing with Background Radioactivity for Maine Yankee Final Status Surveys, Attachment E to Maine Yankee Procedure PMP 6.7.8, FSS Data Processing and Reporting
- 6. Maine Yankee Engineering Calculation, EC-004-04, submitted to the NRC under letter MN 05-002 in January 2005 FR-0220-01, Revision 0 Page 7 of 21
Attachment 1 Survey Unit Maps FR-0220-01, Revision 0 Page 8 of 21
Main IMap Yanee Mainte Yanktee Decommtissionintg ID#-
Ma ine Yankee ProjectSurvey Form IR0220-01 Decommissioning Team uSp TRaorrcvo Survey Type: El Characterization M Turnover
- Final Status Survey I Survey Area Name: Spare Transformer Excavation Pit 623,000 E 623,500 E 624,000 E 624,500 E 625,000 E l I I r r1UKU4 MN 0 400 8Go 1200 4ZOD N FR-0220-01, Revision 0 Page 9 of 21
Maine Yankee YankeapR-ID#:0 I Decommissioning Team IMaine YankeeDcomnnissioning ProjectSurvey FormlFR-022 Survey Type: 0 Characterization 0 Turnover X Final Status Survey ISurvey Area Name: Spare Transformer Excavation Pi Spare Transformer Excavation Pit H-- N Soil Sample Locations 15 10 5
0 0 5 10 15 FR-0220-01, Revision 0 Page 10 of 21
Maine Yankee DecMmisnin g Tneam IMaine Y"ankee DecommissioningProjectSurvey Form lFR-0-0 Map ID #.
Deypommissioning Team 0 TFrmrEcaini Survey Type: 0 Characterization 0 Tumnover 0 Final Status Survey I Survey Area Name: Spare Transformer Excavation Pit Spare Transformer Excavation Pit N Scan Locations 15 10 5
0 0 5 10 15 Denotes Soil Sample Locations
+o OF Denotes 1 Meter Square Scan Areas Except S019 and S021 Which Are 2 Meter Square Scan Areas FR-0220-01, Revision 0 Page 11 of 21
Maine Yankee Al *
- O S** F* Map ID #:
Decommissioning Team IMan Yatikee Decom;:nfsslo1:idgPboject Sun~~ey Foii XR 0220O02 Survey Type: E Characterization E Turnover N Final Status Survey ISurvey Area Name: Spare Transformer Pit Spare Transformer Pit Unit 1 Soil Scan 3}- N MN Grid 31 9 8 7 4 5 6 I 4 3 2 1 FR-0220-01, Revision 0 Page 12 of 21
Attachment 2 Survey Unit Instrumentation FR-0220-01, Revision 0 Page 13 of 21
TABLE 2-1 FIELD INSTRUMENT INFORMATION E-600 S/N Probe SIN (type) 1927 726560 (SPA-3) 1625 725328 (SPA-3) 1641 726560 (SPA-3) 1648 726554 (SPA-3)
GR-130 SIN l IDC (pCi/g) l 11177 1177 l Cs-137 Co-60 0.423 1.16 j HPGe Detectors for Lab Analysis of Volumetric Samples Detector Number MDC (pCi/g)
FSS-1 0.04 - 0.10 FSS-2 1 0.04 -0.10 TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, AND INVESTIGATION LEVEL Detector J SPA-3 J Comments Scan MDC 5 Design Scan MDC, (pCi/g) . LTP Table 5-6 (Reference 3)
DCGL Approved DCGL for land areas (pCi/g) 4.2 outside the Restricted Area,
._ LTP Section 6.7 (Reference 2)
Investigation Level 15,800 Soil (Alarm Setpoint)
(cpm) 16,600 Ledge / Rock FR-0220-01, Revision 0 Page 14 of 21
Attachment 3 Investigation Table FR-0220-0 1, Revision 0 Page 15 of 21
TABLE 3-1 INVESTIGATION TABLE
__ __ FSS SURVEY RESULTS INVESTIGATION RESULTS Alarm Scan Sub-Grid Grid Reason Setpoint Measurement Scan Sample ID CS-137 DCGL GiRes Sepm e Measurement (GR-130) (pCi/g) Comparison (cpm) (cpm) (cpm) _ _ __ _
S031 ALARM 16,600 17,050 17,060 S031/2 <0.423 <DCGL 16,850 S031/3 <0.423 <DCGL 17,340 S031/5 <0.423 <DCGL 16,830 S031/7 <0.423 <DCGL i 17,370 S031/9 <0.423 <DCGL SU Mean / DCGL 0.013 Total 0.013 NOTES: 1. "<"indicates value less than MDA. MDA value is shown.
- 2. The samples were also analyzed forCo-60; all vere less than an MDA ofl.16pCi/g.
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Attachment 4 Statistical Data FR-0220-01, Revision 0 Page 17 of 21
Survey Package FR0220 Unit 1 Soil Sign Test Summary
'I .;-'-Evluatfc'2 orni-ents '
Survey Package: FR0220 Survey Unit: 01 Evaluator: DR DCGL^,: 4.20E+00 DCGLemc: NIA LBGR: 3.69E+00 Sigma: 1.70E-01 Type I error: 0.05 Type II error: 0.05 Nuclide: CS-137 Soil Type: N/A
> :. Calculated -'-!' oC.ts ZIt: 1.645 Z1.0: 1.645 Sign p: 0.99865 Calculated Relative Shift: 3.0 Relative Shift Used: 3.0 Uses 3.0 if Relative Shift is >3 N-Value: 11 N-Value+20%: 14 Number of Samples: 14 Median: 5.56E-02 Mean: 5.52E-02 Net Sample Standard Deviation: 4.75E-03 Total Standard Deviation: 4.75E-03 Sum of samples and reference Maximum: 6.14E-02 i X stS est < < _ _ __ _ _ __ o
_ _ __enults;4s, Adjusted N Value: 14 S+ Value: 14 Critical Value: . 10 Sign test results:, Pass Sufficient samples collected: Pass Maximum value <DCGL,: Pass Median value <DCGL,: Pass Mean value <DCGL:: Pass Maximum value <DCGLn,: Pass Total Standard Deviation <=Sigma: ; :Pass Criteria comparison results: l Pass
,lwu?
S'at _S.'K-P. %Iommo The survey unit passes all conditions:l - Pass FRo220-SUI-SoilSign 3r2105 1:40 PM FR-0220-01, Revision 0 Page 18of21
FR-0220 SU-1 Quantile Plot 0.07 .7 0.06 ,
0.05 0
4-
%._0
- ? t'J 0.04
- Activity (pCi/g) I b 100-a,
- <f
._U 4-a 0.03 -Median (pCi/g)
Ox 0
A: 0.02 0.01 **1 0
0 25 50 75 100 Percent
One-Sample T-Test Report Page/Date/Time 2 3/2/05 11:52:54 AM Database C:\Program Files\NCSS97\FR0220SU1.S0 Variable C2 Plots Section Histogram of FR-0220, SU-1 U) 0.C E
Cu E
z Activity (pCilg)
FR-0220-01, Revision 0 Page 20 of 21
One-Sample T-Test Power Analysis Page/Date/Time 2 312/05 11:55:24 AM Chart Section Retrospective Power Curve 1.0 0.8 I
L_
a, 0.6 .. \ ----- - - ----
0 EL * . *- - - - - I 0.4 7 -- - - - - - -. \ - - - - - -
0.2 0.0 I I I I sl 0
Survey Unit Mean (pCi/g)
FR-0220-01, Revision 0 Page 21 of 21