ML051050099
| ML051050099 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 04/04/2005 |
| From: | Ambrose J, Olsen C, Packer J, Pillsbury G, Tozzie R Maine Yankee Atomic Power Co |
| To: | NRC/FSME |
| References | |
| FR-0200-03, Rev 0 | |
| Download: ML051050099 (20) | |
Text
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0200 YARD EAST SURVEY UNIT 3 Prepared By: __ Date: sJar:,.P SEnginrSignature Printed Name Reviewed By: Date: 33 o0w HS fiQgnAnature Printed Name Reviewed By: W e? G v Date: 3 ° 0si~
Independent Review nature
//7Printed arne Approved By: Date: _____
PSSnted -Signature Printed Name Revision 0
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0200 YARD EAST SURVEY UNIT 3 A. SURVEY UNIT DESCRIPTION FR-0200 Yard East Survey Unit 3 was located in the SE corner of the site, residing in the former "Industrial Area" yard. The 1687 m2 area was bordered on the north by FR-0200 Survey Units 9 and 4 and on the west by FR-01 11 Survey Unit 17. Survey Unit 3 is bounded by FR-0200 Survey Unit I to the South and East. The survey unit is located within the current Restricted Area (RA) and includes a 4 meter wide buffer zone outside the RA. This survey unit is contained within the triangular coordinates 623965E, 407343N; 623992E, 407469N; and 624228E, 407418N using the Maine State Coordinate System (West Zone)
NAD 1927. The location of the survey unit in relation to the Turbine Building and the proximate FR-0200 survey units is shown on map FR0200 REF (Attachment 1).
Survey Unit 3 is an area composed primarily of soil and backfill, and is relatively flat.
B. SURVEY UNIT DESIGN INFORMATION Survey Area FR-0200 was originally designed as a Class 3 area per LTP Revision 3. During decommissioning, the RA boundary was expanded to include a portion of FR-0200 including Survey Unit 3. Thus, Survey Unit 3 was reclassified to Class 1. 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. (It was later realized that a higher DCGL for areas with only surface soil contamination could have been used, resulting in a requirement for only 18 direct measurements.) 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 42 locations which are illustrated on map FR0200-3b (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 1687 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-m2 fields of view. The ISOCS detector was positioned perpendicular to the surface.
Locations of the 90 survey scans are shown on map FRO200-3a (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 DCGLEMC. 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-0200-03, Revision 0 Page 2 of 20
TABLE I SURVEY UNIT DESIGN PARAMETERS Survey Unit j Design Criteria l Basis Area 1687 m2 Class 1, < 2,000 m2 Based on an LBGR of 1.2 Number of Direct 40 pCi/g, sigmal of 1.33 pCi/g and Measurements Required a relative shift of 0.8.
2_ 1 Type = Type 11 = 0.05 Sample Area 42 m2 1687 m /40 = 42 m Sample Grid Spacing 6.5 m (42)1/2 Scan Grid Area ISOCS scan at 3 meters See Section B Area Factor 1.6 Class I Area, LTP Table 6-12 Scan Area 1687 m2 Class I Area - 100%
Background 2>K§ _7, 77'1?'-i -
SPA-3 (scan)
..10 pCi/g Cs-137 ISOCS investigation levels with Scan Investigation Level 0.36 pCi/g Co-60 detector at 3-meter height 0.36 o-60(Reference
~ifg 6)
DCGL 2.39 pCi/g Cs-137 (References 4 and 7)
_____ _____ _____ 0.86 pC i/g C o-60_ _ _ _ _ _ _ _ _ _ _ _ _
3DCGL x Area Factor for Class Design DCGLENMc 3.8 pCi/g Cs-137 1 survey unit, per LTP Section 5.6.3 C. SURVEY RESULTS A total of 42 direct measurements were performed in Survey Unit 3. One sample contained Cs-1 37 with levels of residual activity greater than the MDA but below the DCGL. No samples contained detectable Co-60 activity. All other measurements were below the MDA.
The results are presented in Table 2. No investigations were necessary or performed based on the direct measurement results.
ISOCS gamma scans were performed at 90 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. Therefore, no investigation surveys were performed as a result of the scan surveys.
LTP Revision 3, Table 5-IC for RCA Yard West, R0100 FR-0200-03, Revision 0 Page 3 of 20
TABLE 2 DIRECT MEASUREMENTS Sample Number Cs-137 (pCi/g) Uncertainty (pCi/g)
FRO20003ISOOI < 5.97E-02 FR020003 1S002 < 3.53E-02 FR020003 I S003 < 4.36E-02 FR0200031S004 < 4.99E-02 FR0200031S005 < 4.76E-02 FR0200031S006 < 4.15E-02 FR0200031S007 < 4.66E-02_
FR0200031S008 < 5.63E-02 FR0200031S009 < 3.62E-02 FRO200031SO10 1.15E-01 3.82E-02 FRO200031SOII < 5.35E-02 FR0200031S012 < 5.40E-02 FR0200031S013 < 4.94E-02 FR0200031S014 < 4.42E-02 FR0200031S015 < 5.32E-02 FR0200031S016 < 4.89E-02 FR020003 1S017 < 3.84E-02 FR0200031S018 < 4.18E-02 FR0200031SO19 < 4.96E-02 FR020003 1S020 < 4.59E-02 FR020003 1S021 < 5.05E-02 FR0200031S022 < 5.15E-02 FR020003 1S023 < 5.55E-02 FR020003 1S024 < 4.441E-02 FR020003 1S025 < 3.84E-02 FR020003 1S026 < 3.89E-02 FR020003 I S027 < 4.23E-02 .
FR020003 1S028 < 4.84E-02 FR020003 1S029 < 4.53E-02 FR0200031S030 < 5.68E-02 FRO200031S031 < 5.49E-02 FRO200031S032 < 4.41E-02 FR0200031S033 < 4.74E-02 FR0200031S034 < 5.88E-02 FR0200031S035 < 6.70E-02 FR0200031S036 < 6.03E-02 FR0200031S037 < 6.51E-02 FR0200031S038 < 5.42E-02 FR0200031S039 < 4.1OE-02 FR0200031S040 < 5.67E-02 FR0200031S041 < 4.55E-02 FR020003 I S042 < 7.24E-02 Mean 5.12E-02 Median 4.92E-02 Standard Deviation 131E-02 Range 3.53E-02 to 1.15E-O1
"<" indicates MDA value. Bold indicates positive detection value.
No Co-60 detected above an MDA of 0.1 pCi/g.
FR-0200-03, 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. Ofthe 42 soil samples collected, one 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 are listed in Table 2. The mean and median activities were less than the DCGL for Cs-137. The average of the Cs-1 37 measurements was 0.051 pCi/g, indicating that the direct measurements averaged 2.1% of the DCGL limit.
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 (0.051 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. The Quantile Plot was generated from the unity data listed in Table 2. The data set and plot are consistent with expectations for a Class I survey unit. All of the measurements are below the DCGL of 2.39 pCi/g for Cs-137.
2 See Attachment E to Maine Yankee Procedure PMP 6.7.8 (Reference 5).
FR-0200-03, Revision 0 Page 5 of 20
- 3. A Histogram Plot wvas also developed. This plot shows a log-normal distribution with one outlier.
- 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 1 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 performed and evaluated in the March 2005 time frame. The design was performed to the criteria of the LTP Revision 3 (References 2 and 4). No subsequent LTP changes with potential impact to this survey unit need to be evaluated.
I. 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.
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 Table1. 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-137 and 0.36 pCi/g Co-60. Therefore, no investigations were required as a result of the scan process.
It is concluded that FR-0200 Survey Unit 3 meets the release criteria of IOCFR20.1402 and the State of Maine enhanced criteria.
FR-0200-03, Revision 0 Page 6 of 20
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-0200-03, Revision 0 Page 8 of 20
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llainp Yankee Decommissioning Team Maine Yankee DecommissioningProjectSurvey Forni IDate: 3/14/05 Survey Type: El Characterization El Turnover I Final Status Survey I Survey Area Name: RCA Yard East Soils Final Status Survey FRO200: RCA Yard East Soils Survey Units 3-9 Reference Map 7
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FR-0200-03, Revision 0 Page IOof20
Maine Yankee Map ID#: FRO200-3a Decommissioning Team Maine Yankee DecommissioningProjectSurvey Form Date: 2/21IO5 Survey Type: 0 Characterization 0 Turnover 1 Final Status Survey Survey Area Name: RCA Yard East Soils Final Status Survey FRO200 SU3: RCA YardEast Soils Survey Scans S001 - S090 2 40,n, -
4.8rnt Typical ISOCS Spacing (Naxkniq FR-0200-03, Revision 0 Page I1 of 20 Surface Area = 1687 sq-m
Maine Yankee Map ID#: FRO200-3b Decommissioning Team MAfaine Yankee DecontmissioningProjectSurvey Form Date: 1/11105 Survey Type: 0 Characterization L Turnover 1 Final Status Survey Survey Area Name: RCA Yard East Soils Final Status Survey FRO200 SU3: RCA YardEast Soils Direct Points S001 - S042 407,343.2.
HMN A D,4 FR-0200-03, Revision 0 Page 12 of 20
- urface Area = 1687 sq-m N=40 L=
Attachment 2 Survey Unit Instrumentation FR-0200-03, Revision 0 Page 13 of 20
TABLE 2-1 INSTRUMENT INFORMATION ISOCS Detectors (Field Measurements)
Detector No. MDC (pCi/g) 7605 0.11 to 0.30 7607 0.10 to 0.34 7780 0.1Oto 0.31 HPGe Detectors (Laboratory Analysis)
Detector No. MDC (pCi/g)
FSS1 0.04 to 0.08 FSS2 0.04 to 0.09 TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, INVESTIGATION LEVEL, AND DCGLENIC Parameter Instrument: ISOCS Comments Scan MDC 0.10 to 0.34 pCi/g - 25% DCGL 2.3 9 pCi/g Cs-i1 3 7 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)
DCGL x Area Factor for Design DCGLEMC 3.8 pCi/g Cs-137 Class I survey unit, per LTP 1.4 pilg o-60Section 5.6.3 FR-0200-03, Revision 0 Page 14 of 20
Attachment 3 Investigation Table (There were no Investigations)
FR-0200-03, Revision 0 Page 15 of 20
Attachment 4 Statistical Data FR-0200-03, Revision 0 Page 16 of 20
Survey Package FRO200 Unit 3 CS-137 Soil Sign Test Summary uation
-."-'Eva __nput__Iues__ 'en-ints-I- ornm Survey Package: FR0200 Survey Unit: 03 Evaluator: Andy Olsen DCGL,: 2.39E+00 Cs-137 DCGLe,: 3.76E+00 AF = 1.6 LBGR: 1.20E+00 50% of DCGL Sigma: 1.33E+00 LTP Rev 3, Table 5-1 C Type I error: 0.05 Type II error: 0.05 Nuclide: CS-137 Soil Type: N/A No material background is applied.
~ V Itc-T -- r~nmhts<:-
% 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
,, >,>,.S .' Samnplo Daa Value tz,,>S~ rnment t Number of Samples: 42 Median: 4.92E-02 Mean: : 5.12E-02 Net Sample Standard Deviation: 1.30E-02 Total Standard Deviation: 1.30E-02 Sum of samples and reference Maximum: 1.15E-01 Wgn Test esu on Adjusted N Value: 42 S+ Value: 42 Critical Value: 26 Sign test results:, Pass Sufficient samples collected: Pass Maximum value <DCGL,: Pass Median value <DCGLw: " Pass Mean value <DCGLW: Pass Maximum value <DCGLenc: Pass Total Standard Deviation <=Sigma: Pass Criteria comparison results: - Pass
_________________survey___u passes_______orn Peas The survey unit passes all conditions _______________Pass____
FR-0200-03, Revision 0 Page 17 of 20
FRO200 SU-3 Quantile Plot 0.14 0.12 0.1 0 0.
0.08 -I
- Activity (pCi/g) co 00' o
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0.06 ". .. -Median (pCi/g)I 50 ._
.... , . .,* * + 19, , 6 4*o 0.04 0.02 -I 0
0 25 50 75 100 Percent
One-Sample T-Test Report Page/Date/Time 2 3/22/05 4:02:03 PM Database Variable C2 Plots Section Histogram of FR-0200, SU-3 25, In
- 0. 19 E
tu 13
-0 U) z 6 0 020
. . - .. .Activity 0.045 .. .. .. ...
. . . .(pCilg) 0.070 0.095 0.120 FR-0200-03, Revision 0 Page 19 of 20
-I One-Sample T-Test Power Analysis Page/Date/Time 2 3/31/05 10:04:16 AM Chart Section Retrospective Power Curve 1.0 _ . .-
0.8- .. -.- *.-
a3 0.6- . ------..-..
0 0.4- .-. .------------
0.2-0.0 I 0.0 0.5 1.0 1.5 2.0 2.5 Survey Unit Mean (pCi/g)
FR-0200-03, Revision 0 Page 20 of 20