ML050590090
| ML050590090 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 02/17/2005 |
| From: | Dockins L, Madison G, Olsen C, Packer J, Pillsbury G Maine Yankee Atomic Power Co |
| To: | Document Control Desk, NRC/FSME |
| References | |
| FR-0100-03, Rev 0 | |
| Download: ML050590090 (20) | |
Text
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0100 RCA YARD WEST SURVEY UNIT 3 Prepared By: K MD yg S 1 ature Date: ______.___t nted Name Reviewed By: Date: ______ 2___
FSS pecialist - Signature P~bted Name Reviewed By: ___ Date:
Indpendenp Review - Signature
,f~-rinjddNapie Approved By: a l , ae ?/c/-OSA
- Signature Printed 0me Approved By: / Date:
FSS, MOP - Sgnature Printed Name Revision 0
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0100 RCA YARD WVEST SURVEY UNIT 3 A. SURVEY UNIT DESCRIPTION FR 0100 RCA Yard West Survey Unit 3 was located south of the former Containment Building and encompassed portions of areas that were originally surveyed under packages FR-0111-07, FR-1000-01, FR-0400-0I,and FR-0400-02. Additionally, a portion ofFR-0100 Survey Unit 3 was not originally included under any other survey package. The 1476 m2 area is located at coordinates 407,290 N and 623,761 E using Maine State Coordinate System (fVest Zone) NAD 1927. The location of the survey unit in relation to the Containment Building and the surrounding site features are shown on map FR 0100-3 SITE (Attachment 1).
Survey Unit 3 is an area composed primarily of soil and backfill, and is relatively flat or gently sloping. The southern portion is a sharp sloping ravine with exposed ledge walls.
Map FRO100-3 REF (Attachment 1) indicates the survey unit boundaries and gradients.
B. SURVEY UNIT DESIGN INFORMATION Survey Unit 3 met the LTP Revision 3 definition for a Class I survey unit. The survey unit design parameters are shown in Table 1. Given a relative shift of 0.8, it was determined that 40 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=40 design led to a survey unit map with 43 locations which are illustrated on map FRO I00-3 DP REF (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 1476 m2 area were required for the Class I 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-mi2 fields of view. The ISOCS detector was positioned perpendicular to the surface.
Locations of the 83 survey scans are shown on map FRO100-3a (Attachment 1).
The ISOCS scans were configured to ensure 100% scan coverage of all exposed surfaces within Survey Unit 3. 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 DCGLENC. 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. Further, since the investigation level was always less than the design DCGLEMC, no EMC sample size adjustment was necessary.
FR-0 100-03, Revision 0 Page 2 of 20
TABLE 1 SURVEY UNIT DESIGN PARAMETERS Surmey Unit Design Criteria Basis Area 1,476 m2 Class 1, < 2,000 m2 Number of Direct Based on an LBGR of 1.2 pCi/g, sigmal of Meaurembent Requi40 1.33 pCi/g and a relative shift of 0.8.
Measurements Required Type I = Type II = 0.05 Sample Area 37 m2 1,476 m2 / 40 = 37m 2 Sample Grid Spacing 6.1 m (37)1/2 Scan Grid Area ISOCS scan at 3 See Section B meters Area Factor 1.6 Class 1 Area, LTP Table 6-12 Scan Area 1,476 m2 Class 1 Area - 100%
1.0 pCi/g Cs-137 ISOCS investigation levels with detector Scan Investigation Level 0.36 pCi/g Co-60 at 3-meter height 0.36 ~ilg o-60 (Reference 6)
DCGL 2.39 pCi/g Cs-137 References 4 and 7
_____ _____ ____ 0.86 pC i/g Co-6O0_ _ _ _ _ _ __ _ _ _ _ _ _ _ _
Design DCGLENC1.38 3.82 pCi/g Cs-137 DCGL x Area Factor for Class I survey g pCi/g Co-60 unit, per LTP Section 5.6.3 C. SURVEY RESULTS A total of 43 direct measurements were performed in Survey Unit 3. Twelve samples contained Cs-137 with levels of residual activity below the DCGL. No samples contained Co-60. All other measurements were below the MDA. The results are presented in Table 2.
No investigations were necessary or performed as a result of the direct measurements.
ISOCS gamma scans were performed at 83 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 25% of the DCGL. All identified scan activity levels and MDAs were below the investigation levels. Co-60 was not detected above the MDA in any of the measurements. Therefore, no investigation surveys were performed as a result of the scan surveys.
LTP Revision 3, Table 5-1C for RCA Yard West, ROIOO FR-O100-03, Revision 0 Page 3 of 20
TABLE 2 DIRECT MEASUREMENTS Sample Number Cs-137 (pCi/g) l Uncertainty (pCi/g)
FRO1000301SOOIl < 5.26E-02 _ _ _
FR01000301S002 < 5.39E-02 FRO1000301SO03 < 5.98E-02 FRO1000301SO04 9.36E-02 2.82E-02 FR01000301S005 6.50E-02 2.651E-02 FR01000301SO06 1.12E-01 3.24E-02 FRO1000301S007 2.18E-01 3.78E-02 FRO1000301SO08 1.09E-01 3.29E-02 FRO1000301SOO9 1.27E-01 3.OOE-02 FR01000301SO10 < 6.38E-02 FR01000301SOII 7.61E-02 2.26E-02 FR01000301S012 < 6.14E-02 FR01000301S013 < 6.18E-02 FRO1000301SO14 < 5.04E-02 FRO1000301SO15 < 5.29E-02 FR01000301S016 < 5.22E-02 FR01000301S017 < 5.78E-02 FR01000301S018 1.17E+00 9.38E-02 FRO1000301SO19 < 6.58E-02 FRO1000301SO20 < 4.94E-02 FR01000301S021 1.22E-01 3.15E-02 FR01000301S022 < 5.79E-02 FR01000301S023 < 5.12E-02 FR01000301S024 7.75E-02 2.45E-02 FR01000301S025 < 4.53E-02 FR01000301S026 < 5.22E-02 FR01000301S027 < 5.57E-02 FR01000301S028 < 5.15E-02 FR01000301S029 < 4.98E-02 FRO1000301SO30 < 5.92E-02 FRO1000301SO31 < 5.92E-02 FR01000301S032 < 6.03E-02 FR01000301S033 < 5.20E-02 FR01000301S034 < 5.53E-02 FR01000301S035 < 4.94E-02 FR01000301S036 < 5.17E-02 FR01000301S037 < 5.90E-02 FR01000301S038 < 5.95E-02 _ _ _
FR01000301S039 1.63E-01 3.80E-02 FRO1000301SO40 < 5.42E-02 FRO1000301SO41 < 5.53E-02 FR01000301S042 < 5.46E-02 FRO1000301S043 1.25E-01 3.19E-02 Mean 9.70E-02 Median 5.90E-02 Standard Deviation 1.71E-OI Rance 4.53E-02 to 1.17E+OO
"<" indicates MDA value. Bold indicates positive detection value. No Co-60 detected above MDA.
FR-0100-03, Revision 0 Page 4 of 20
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 43 soil samples collected, 12 positively identified Cs-137 activity below the DCGL value of 2.39 pCi/g and no samples identified Co-60 activity. All other values were below the MDA. Identified sample activities or Minimum Detectable Activities for Cs-137 are listed in Table 2. The mean and median activities wvere less than the DCGL for Cs-137. The average of the Cs-137 measurements was approximately 0.10 pCi/g, indicating that the direct measurements averaged 4.1% of the DCGL limit.
Based on the Sign Test contained in Attachment 4, it is apparent that the general residual radioactivity within the survey unit is less than the DCGL and is in compliance with the release criteria. Because the S018 direct measurement is more than three standard deviations above the mean value for the survey unit direct measurements, it appears to be an outlier of small size.
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 (0.10 pCi/g). This would equate to an annual dose rate of 0.0 mrem/year.
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.
I. 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. 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 See Attachment E to Maine Yankee Procedure PMP 6.7.8 (Reference 5).
FR-0100-03, Revision 0 Page 5 of 20
- 2. The Quantile Plot was generated from the Cs-137 activity data listed in Table 2. The data set and plot are consistent with expectations for a Class 1 survey unit. All of the measurements are below the DCGL of 2.39 pCi/g for Cs- 137 for land inside the restricted area. The one outlier is due to the identification of Cs-137 at S018 at approximately 49%
of the DCGL.
- 3. A Histogram Plot was also developed based on the Cs-137 activity data values. This plot shows a log-normal distribution with one outlier (S018).
- 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 3 was designed, performed, and evaluated in the December 2004 to February 2005 time frame. The design was performed to the criteria of the LTP Revision 3 (References 2 and 4). Maine Yankee 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. This change had no impact on Survey Unit 3 since this survey only applied to surface soil and there were no Co-60 results above MDA. 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 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 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 2.39 pCi/g Cs-137. 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.
FR-0100-03, Revision 0 Page 6 of 20
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.
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 3 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-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 0100 Survey Unit 3 meets the release criteria of IOCFR20.1402 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 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
Attachment 1 Survey Unit Maps FR-0100-03, Revision 0 Page 8 of 20
Decommissioning Team Maine Yankee DecommissioningProjectSurvey Form Map ID #: FR 0100-3 SITE Decomisionig Tam Revised: 12121104 Survey Type: 0 Characterization 0 Tumover
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Maine Yankee Map ID #: FRO100-3a D mn e Maine Yankee DeconzinissioningProjectSurvey Rorit Date: 2/16/05 Survey Type: 0 Characterization l Turnover Final Status Survey I Survey Area Name: RCA Yard West Soil Final Status Survey FR0100 Survey Unit 3: RCA Yard West Soil ISOCS Scan Map S001 - S083 I
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FR-0 100-03, Revisior 0 Page 12 of 20 ISOCS at 3m above ground level.
Field of view is approximately 06.0m. Total Surrace Area for SU3 is approx 1476 sq-m.
Attachment 2 Survey Unit Instrumentation FR-0100-03, Revision 0 Page 13 of 20
TABLE 2-1 INSTRUMENT INFORMATION ISOCS Detectors (Field Measurements)
Detector No. MDC (pCi/g) 7607 0.18 to 0.32 7722 0.15 to 0.33 7780 0.14 to 0.31 HPGe Detectors (Laboratory Analysis)
Detector No. MDC (pCi/g)
FSS1 0.04 to 0.07 FSS2 0.03 to 0.06 TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, INVESTIGATION LEVEL AND DCGLENIC Detector Instrument: ISOCS Comments Scan MDC 0.14 to 0.33 pCi/g - 25% DCGL 2.39 pCi/g Cs-137 Approved DCGL for land DCGL 0.86 pCi/g Co-60 areas inside the Restricted Area, (References 4 and 7)
Investigation Level 1.0 pCi/g Cs-137 (ISOCS ( 3 m) 0.36 pCi/g Co-60 (Reference 6)
Di1C-60 DCGL x Area Factor for Design DCGLE51C 3.82 pCilg Cs 3 Class I survey unit, per 1.38 pCi/g Co-60 LTPI Section 5.6.3 FR-0100-03, Revision 0 Page 14 of20
Attachment 3 Investigation Table (No Investigations Required)
FR-0100-03, Revision 0 Page 15 of 20
Attachment 4 Statistical Data FR-0100-03, Revision 0 Page 16 of 20
Survey Package FRO100 Unit 3 CS-137 Soil Sign Test Summary
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Survey Package: FROIOO Survey Unit: 03 Evaluator: Andy Olsen DCGL,,: 2.39E+00 Cs-137 DCGLem: 3.82E+00 AF = 1.6 LBGR: 1.20E+00 50% of DCGL Sigma: 1.33E+00 LTP Rev 3, Table 5-1C Type I error: 0.05 Type II error: 0.05 Nuclide: CS-1 37 Soil Type: NIA No material background is applied.
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Z *: 1.645 1.645 Sign p: 0.788145 Calculated Relative Shift: 0.8 Relative Shift Used: : 0.8 Uses 3.0 if Relative Shift is >3 N-Value: ' 33 N-Value+20%: . 40 Number of Samples: :43 Median: 5.90E-02 Mean: -- *9.70E02 Net Sample Standard Deviation: .. ; '11.711E-01 ________________
Total Standard Deviation: 1.71 E-01 Sum of samples and reference Maximum: - -. 1 17E+00 Adjusted N Value: -. 43 S+ Value: _ _ _ _ _ __43 Critical Value: ; -. 27 Sign test results: . ,-;Pass Sufficient samples collected: -. 2 Pass Maximum value <DCGL,: ; Pass Median value <DCGL..: Pass Mean value <DCGL,: Pass Maximum value <DCGL,,: 'Pass Total Standard Deviation <=Sigma: - Pass Criteria comparison results: v Pass_
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FThe survey unit passes all conditions:l*.' .. *Pass FR-0 100-03, Revision 0 Page 17 of 20
FR-0100 SU-3 Quantile Plot 1.40E+00 1.20E+00 1.OOE+00 0
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One-Sample T-Test Report Page/Date/Time 2 2/17/05 9:11:09 AM Database C:\Program Files\NCSS97\FRO100SU-3.SO Variable C2 Plots Section Histogram of FR-0100, SU-3 60-
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6.306 6.9o6 . .200 Activity (pClg)
FR-0100-03, Revision 0 Page 19 of 20
One-Sample T-Test Power Analysis Page/Date/Time 2 2/17/05 9:11:56 AM Chart Section Retrospective Power Curve 1.0- .
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0.0 0.5 1.0 1.5 2'0 2'5 Survey Unit Mean (pCi/g)
FR-01 00-03, Revision 0 Page 20 of20