ML043500360
| ML043500360 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 12/07/2004 |
| From: | Pillsbury G, Randall D Maine Yankee Atomic Power Co |
| To: | NRC/FSME |
| References | |
| FR-0500-02, Rev 0 | |
| Download: ML043500360 (21) | |
Text
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0500 BAILEY POINT SURVEY UNIT 2 Prepared By: s-" z, Date: /7- Z-_0 FSS Engineer - Signature Printed Name Reviewed By: Fsgnintre Date: ILL."q Printed Name Reviewed By: ____________ Date: ;Z hi. @'
Independent Review-- Signature 1s, rn~d ..,/
Approved By: _/ ,Dae Z/7 Printed Name Approved By: __,_ _______ Date:
/ISS, MOP - Signature rinted Name Revision 0
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0500 BAILEY POINT SURVEY UNIT 2 A. SURVEY UNIT DESCRIPTION Survey Unit FR-0500 Survey Unit 2, Bailey Point, consists of the land area making up the peninsula to the south of the of the secondary side (east side) yard. It consists of open and wooded land areas. The survey unit is traversed from north to south by a gravel road. It is not inclusive of a small Class I area, which takes up an 8 m by 8m square near the center of the survey unit'. Survey Unit 2 is located around grid coordinates 407,000 N and 624,250 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 FR 0500 SITE.
All maps referenced in this release record are provided in Attachment 1, unless otherwise noted. The survey unit total area is approximately 14,400 in2 (3.5 ac).
B. SURVEY UNIT DESIGN INFORMATION The area was designated a Class 3 land survey unit per the LTP (Table 5-1 C). 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 0500 DP SU2. All direct measurements consisted of soil samples obtained at the required locations. The samples are analyzed with laboratory gamma spectroscopy.
Scan grids of nominally 2 m x 4 m were established as indicated on survey maps FR 0500 SS REF. A 1% to 10% scan coverage of the area was required. The 183 scan grids provided a total scan area of approximately 1464 m2 , exceeding the 10% 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 and to confirm the scan MDCs used were appropriate. Due to variability in background within the survey unit, the grids were divided into nine different background groups based on the location as shown on map FR 0500-02BK. These are specified in Table 1.
A small quantity of contaminated soil was discovered within this area during the site characterization. This area was remrediated as part of the characterization effort. In accordance with the License Termination Plan (LTP), (Reference 3) the subject area was classified into a Class I survey unit (FR-0500, Survey Unit 1).
The Class I unit was expanded to eliminate the need for a Class 2 buffer unit. However, scans for Survey Unit 2 were biased around the Class I area.
FR-0500-02, Revision 0 Page 2 of 21
TABLE 1 SURVEY UNIT DESIGN PARAMETERS Survey Unit Design Criteria Basis Area 14,400 m2 No limit for Class 3 Area Based on an adjusted LBGR of Number of Direct 14 3.36 pCi/g, sigma2 of 0.28 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 Approximately 2m x 4m Class 3 Area Area Factor N/A Class 3 Area Scan Survey Area 1464 m2 Class 3 Area 1% - 10%
Background i
- i2,'.
SPA-3 (scan) 9,090 cpm Group 8 9,565 cpm Group 5 9,795 cpm Group 9 10,335 cpm Group 7 10,345 cpm Group 4 10,645 cpm Group 2 10,880 cpm Group 6 11,015 cpm Group 3 11,520 cpm Group I Scan Investigation Level 3 Sigma of Background EC-009-01(Reference 1) plus Background See Table 2-2 DCGL 4.2 pCi/g LTP Revision 3 (Reference 2 and 3)
Design DCGLaIc N/A Class 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. Nineteen verified alarms were received during the soil scans. The investigation of verified alarms is discussed below.
2 Design sigma based on LTP Revision 3, Table 5-IC, Bailey Point, FR-0500.
FR-0500-02, Revision 0 Page 3 of 21
TABLE 2 DIRECT MEASUREMENTS Sample Number Cs-137 (pCilg)3 Uncertainty FR-0500-02-SOOI 1.48E+00 + 1.62E-01 FR-0500-02-S002 5.17E-01 + 6.72E-02 FR-0500-02-S003 <4.89E-02 N/A FR-0500-02-S004 <7.37E-02 N/A FR-0500-02-S005 3.23E-01 + 5.81E-02 FR-0500-02-S006 1.82E-01 + 5.32E-02 FR-0500-02-S007 <4.69E-02 N/A FR-0500-02-S008 3.90E-01 + 8.O1E-02 FR-0500-02-S009 1.49E+00 + 1.42E-01 FR-0500-02-S010 1.96E-01 + 5.10E-02 FR-0500-02-SOI I <5.44E-02 N/A FR-0500-02-S012 1.67E-01 + 4.02E-02 FR-0500-02-S013 7.98E-01 + 1.12E-01 FR-0500-02-S014 5.1 IE-02 + 2.48E-02 Mean 4.16E-01 Median 1.89E-01 Standard Deviation 5.O1E-01 Range 4.69E-02 to 1.49E+00
"<" indicates values less than the MDA, MDA value is reported.
D. SURVEY UNIT INVESTIGATIONS PERFORMED AND RESULTS The soil scan identified nineteen verified alarm locations. An investigation was conducted via survey investigation package XR0500-02. Only environmental levels of Cs-137 (i.e., <
0.3 pCi/g) were detected, all Co-60 results were <MDA. 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.
FR-0500-02, Revision 0 Page 4 of 21
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-137. The maximum direct measurement result was less than 36% of the Cs-137 DCGL. Two samples in Table 2 (S001 and S009) had higher levels of Cs-I 37 than the other samples taken during this survey. However, a review of the measurement locations indicate they were located in wooded areas. The level of activity is not unexpected for undisturbed soil. Further, since the activity is less than the action levels in LTP Table 5-8, 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-1 37 background value (0.19 pCi/g) for disturbed soil from the survey unit sample mean activity (0.416 pCi/g). The result is a net activity value of 0.23 pCi/g. This would equate to an annual dose rate of 0.55 mrem/y. 4 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, except the final sigma was larger than the design value, were clearly satisfied for the FSS of this survey unit.
The direct measurement sample total standard deviation at 0.501 pCi/g was greater than the design sigma. Assuming an LBGR of 50% of the DCGL, and dividing it by the total standard deviation yields a relative shift of 4.2. Since this is greater than the value used of 3, there is no affect on the result.
4 See Attachment E to Maine Yankee Procedure PMP 6.7.8 (Reference 5). Annual dose rate = .23/4.2 x 10 mremly.
FR-0500-02, Revision 0 Page 5 of 2I
- 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 log-normal distribution *vith two outliers.
This result is typical for environmental measurements.
- 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 THE EXTENT OF RESIDUAL ACTIVITY The survey was designed as a Class 3 area; the FSS results were consistent with that classification. Although the direct measurement sample total standard deviation was greater than the design sigma, the evaluation in Section F demonstrates that a sufficient number of sample measurements were taken.
1I. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit 2 was designed, performed and evaluated in mid 2004. The design was performed to the criteria of the LTP, Revision 3 (Reference 4). No subsequent LTP changes with potential impact to this survey unit needed to be evaluated.
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 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 greater than that used for design, but the Section F evaluation indicates 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 variance consistent with expectations for a Class 3 survey unit.
FR-0500-02, Revision 0 Page 6 of21
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 19 verified alarms for evaluation. Attachment 3 shows the areas identified by verified alarms and provides the results, all of which wvere less than DCGL.
It is concluded that FRO500 Survey Unit 2 meets the release criteria of IOCFR20.1402 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 Addenda
- 3. Maine Yankee letter to the NRC, MN-02-06 1, dated November 26, 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.
FR-0500-02, Revision 0 Page 7 of 21
Attachment 1 Survey Unit Maps FR-0500-02, Revision 0 Page 8 of 21
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Attachment 2 Survey Unit Instrumentation FR-0500-02, Revision 0 Page 13 of 21
TABLE 2-1 INSTRUMENT INFORMATION I E-600 S/N I Probe SIN (type) 2489 725890 (SPA-3) 2490 2255 (SPA-3) 2490 726560 (SPA-3) 2621 726560 (SPA-3) 2618 725328 (SPA-3)
HPGe Detectors for Lab Analysis of Volumetric Samples I Detector Number I MDC (pCi/g) l S__S__
-1l_ 0.04 - 0.10 I _ _SS-2 l 0.04 - 0.10 TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, AND INVESTIGATION LEVEL
[ Detector SPA-3 l Comments l Scan MDC Design Scan MDC, (pCi/g) LTP Table 5-6 (Reference 2)
DClL Approved DCGL for land areas (PCilg) 4.2 outside the Restricted Areaa, l ____ ___ _ LTP Section 6.7 (Reference 2)
Investigation Level 3 sigma of Background plus (Alarm Setpoint) Background, EC-009-01 (cpm) (Reference 1) 11,300 (Group 8) 11,840 (Group 5) 12,095 (Group 9) 12,700 (Group 7) 12,710 (Group 4) 13,045 (Group 2) 13,300 (Group 6) 13,450 (Group 3) l 14,010 (Group 1)
FR-0500-02, Revision 0 Page 14 of 21
Attachment 3 Investigation Table FR-0500-02, Revision 0 Page 15 of 21
TABLE 3-1 INVESTIGATION TABLE FSS SURVEY RESULTS INVESTIGATION RESULTS Alarm Scan Scaler CS-137 DCGL Grid Reason Setpoint Measurement Measurement Sample ID (pCi1g) Comparison
_Cpm) (cpm) (cpm) (pig)_ompaiso S016 ALARM 13,045 13,280 12,980 XR0500SO06SS <7.17E-02 <DCGL XRO500SO16RS <7.25E-02 <DCGL SO 17 ALARM 13,045 14,280 14,240 XR0500SO17SS 6.60E-02 + 3.41E-02 <DCGL S043 ALARM 11,840 20,500 20,300 XR0500SO43SS 7.26E-02 + 3.33 E-02 <DCGL S058 ALARM 11,840 12,230 10,680 XRO500SOS8SS <4.60E-02 <DCGL S062 ALARM 11,840 12,280 9,980 XRO500SO62SS <4.80E-02 <DCGL S063 ALARM 11,840 13,210 11,500 XRO500SO63SS <5.03E-02 <DCGL S078 ALARM 10,660 14,380 11,670 XROSOOS078SS <5.95E-02 <DCGL SI 14 ALARM 12,700 16,540 15,400 XROSOOSI 14SS 1.67E-01 + 3.80E-02 <DCGL Si 17 ALARM 12,700 12,950 11,320 XR0500SI 17SS <5.70E-02 <DCGL S 122 ALARM 12,700 14,640 12,620 XROSOOS 122SS 1.48E-01 + 3.75E-02 <DCGL XROSOOS 122RS <5.89E-02 <DCGL S 124 ALARM 12,700 13,860 13,670 XROSOOS 124SS 2.61E-01 + 6.19E-02 <DCGL XROSOOS 124RS <5.31 E-02 <DCGL S 125 ALARM 12,700 12,900 13,490 XR0500S 125SS <4.69E-02 <DCGL S 126 ALARM 12,700 15,010 13,600 XRO500S 126SS <6.60E-02 <DCGL XR0500S 126RS <5.50E-02 <DCGL S 128 ALARM 12,700 15,160 14,170 XR0500S 128SS 1.12E-01 + 5.36E-02 <DCGL XRO500SI28RS <8.95E-02 <DCGL S 129 ALARM 12,700 14,400 13,830 XROSOOS 129SS 6.86E-02 + 3.99E-02 <DCGL S130 ALARM 12,700 14,110 12,600 XRO50OS13OSS <7.58E-02 <DCGL XROSOOSI28RS <5.84E-02 <DCGL S133 ALARM 11,300 15,610 13,340 XR0500S133SS 2.10E-01 + 5.05E-02 <DCGL S 182 ALARM 12,095 12,260 10,290 XRO500SI82SS <4.48E-02 <DCGL S183 ALARM 12,095 12,330 10,140 XRO500SI83SS <4.79E-02 <DCGL SU Mean / DCGL 0.099 Total 0.099 NOTES: 1. "<" indicates value less than MDA, MDA value is reported.
FR-0500-02, Revision 0 Page 16of21
Attachment 4 Statistical Data FR-0500-02, Revision 0 Page 17 of 21
Survey Package FRO500 Unit 2 CS-137 Soil Sign Test Summary
. vaInLut nmep ato luat -l - s1/2*
Survey Package: FRO500 Bailey Point Class 3 Area Survey Unit: 02 Evaluator: DR DCGLw: 4.20E+00 DCGLemc: 4.20E+00 N/A -Class 3 Survey Unit LBGR: 3.36E+00 Sigma: 2.80E-01 Type I error: 0.05 Type II error: 0.05 Nuclide: CS-1 37 Soil Type: N/A
- -- alctulated.Va us' Zoo,
- 1.645 ZI-P: 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 2tAbe"i-,-Saffiold Data ai luesad_:;; dji.~ S imt r
Number of Samples: 14 Median: 1.89E-01 Mean: 4.1 6E-01 Net Sample Standard Deviation: 5.01 E-01 Total Standard Deviation: . 5.01 E-01 Sum of samples and reference Maximum: :. I.49E+00 gf6.S-,'iiT-Tes9t Results cme -
Adjusted N Value: 14 S+ Value: ;; 14 Critical Value: '-. 10 Sign test results: . : Pass L-,'k's:W ruiert'aSaits a ; ... , -.
Sufficient samples collected: . Pass Maximum value <DCGL,,: Pass Median value <DCGL,: Pass Mean value <DCGLW: Pass Maximum value <DCGLc: Pass Total Standard Deviation <=Sigma: per Section F of the RR Oka.ynvestigatO Criteria comparison results: ...f-..:'Investigate Satisfactory The survey unit passes all conditions Investigate SU Meets release Requirements FRO500-SU2-SoilSign-CS-1 37 FR-0500-02, Revision 0 12 /104 6:55 AM Page 18 of 21
FR-0500 SU-2 Quantile Plot 1.6 1.4 1.2 U-C 1
0 m c
- Activity (pCifg) ta .
C 0.8 To
!t :>
VSm - Median (pci/g)I "CD C *Ia 0.6 C.
0.4 ----.-.------.--------.-
0.2
- V 0
0 25 50 75 100 Percent
One-Sample T-Test Report Page/Date/Time 2 12/2/04 8:14:49 AM Database Variable C2 Plots Section Histogram of FR-0500, SU-2
'A EK0 co a)
.0 E
z Activity (pCVg)
FR-0500-02, Revision 0 Page 20 of 21
One-Sample T-Test Power Analysis Page/Date/Time 2 12/6/04 7:26:58 AM Chart Section Retrospective Power Curve 1.0-
- I 0.8-II a) 0.6-1.- - - - \
0 0L \ I 0.4- . I - \ .
0.2- - -I*
0.0 0 i A t Survey Unit Mean (pCi/g)
FR-0500-02, Revision 0 Page 21 of 21