ML051750711
| ML051750711 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 06/07/2005 |
| From: | Olsen C Maine Yankee Atomic Power Co |
| To: | NRC/FSME |
| References | |
| FR-0200-09, Rev 0 | |
| Download: ML051750711 (21) | |
Text
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0200 YARD EAST SURVEY UNIT 9 Prepared By: __ _ Date4Ut 0 2 2005 FLS Engincer - Signature Printed Name Reviewed By: _ Date: 'JUN 0L2 2005' npdS Rfcst - Signature
%-d=-T lo22ztr Printed Name Reviewed By: Date:IJN'O2,05 Independent Rcevicovi - Signature
/7/-Pri,n'tedan/
Approved By: . Date: G/7/6 9eritenqe, -/ignature, Printed Name/
Approved By: hi a tDate: 6/7, w FSS, MOP - Signature Printed Name Revision 0
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0200 YARD EAST SURVEY UNIT 9 A. SURVEY UNIT DESCRIPTION FR-0200 Yard East Survey Unit 9 was located in the southeast corner of the site, mostly residing in the former "Industrial Area" yard. The 1413 m2 area was bordered on the north by FR-0200 Survey Unit 5, on the west by FR-0200 Survey Unit 4, on the south by FR-0200 Survey Unit 3, and on the east by FR-0200 Survey Unit 1. As shown on map FRO200-9 SITE, this survey unit is approximately centered by the coordinates 624183E and 407489N using the Maine State Coordinate System (West Zone) NAD 1927. The location of the survey unit in relation to the Service Building and the surrounding FR-0200 and FR-01 11 survey units is shown on map FRO200-9 REF (Attachment 1). The survey unit is located within the expanded Restricted Area boundary.
Survey Unit 9 is an area composed primarily of soil and backfill. There is a large depression in the survey unit which is approximately two meters deep. It is the former holding pond used to support water removal from FSS and remediation areas during decommissioning.
B. SURVEY UNIT DESIGN INFORMATION Survey Unit 9 was originally classified per the LTP Revision 4 as a Class 3 survey unit, but was reclassified to Class I given its history during decommissioning activities.
The survey unit design parameters are shown in Table 1. Given a relative shift of 1.5, eighteen direct measurements would be required for the Sign Test, but 40 were prescribed as a conservative measure. 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 45 locations which are illustrated on map FR0200-9b (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 1413 m2 area were required for the Class 1 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-rn2 fields of view. The ISOCS detector was positioned perpendicular to the surface.
Locations of the 100 survey scans are shown on map FRO200-9a and 9c (Attachment 1).
The ISOCS scans were configured to ensure 100% scan coverage of all exposed surfaces within Survey Unit 9. 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. Furthermore, since the investigation level was always less than the design DCGLEMC, no EMC sample size adjustment was necessary.
FR-0200-09, Revision 0 Page 2 of 21
TABLE I SURVEY UNIT DESIGN PARAMETERS Survey Unit Design Criteria Basis Area 1413M 2 Class 1, < 2,000m 2 Based on an LBGR of 2.1 pCi/g, Number of Direct sigma' of 1.33 pCi/g, and a relative Measurements Required 18 (40 used for design) shift of 1.5, 18 were required, 45 obtained.
Type I = Type I = 0.05 Sample Area 35 m 2 1413 m2 / 40=35 m 2 Sample Grid Spacing 5.9 m (35)Ifz Scan Grid Area ISOCS scan at 3 meters See Section B Area Factor 1.7 Class 1 Area, LTP Table 6-12 Scan Area 1413 m 2 Class I Area - 100%
1.0 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
~i/g 3)
DCGL4.2 pCi/g Cs-137 DCGL applied to land outside the 1.5 pCi/g Co-60 Restricted Area (Reference 1)
Den DCGL 6.9 pCi/g Cs-137 DCGL x Area Factor for Class 1 DeinDGEC2.5 pCi/g Co-60 survey unit, per LTP Section 5.6.3 C. SURVEY RESULTS A total of 45 direct measurements were performed in Survey Unit 9. Five samples contained detectable Cs-137 with levels of activity greater than the MDA but below the DCGL. Four samples contained detectable Co-60 activity above the MDA but below the DCGL. All other measurements were below the MDA. The results are presented in Table 2. No investigations were necessary as a result of the direct measurements.
ISOCS gamma scans were performed at 100 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 16% 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 4, Table S-IC for RCA Yard West, RO100 (conservative)
FR-0200-09, Revision 0 Page 3 of 21
TABLE 2 DIRECT MEASUREMENTS Sample Number Cs-137 (pCilg) Uncetint Cg0)pcg Uncertainty Unitized Value IIUnertaintY Co-60 (pCi/g) l (pCitg) I FRO200091SO01 < 5.09E-02 < 5.31 E-02 4.75E-02 FR0200091S002 < 4.46E-02 < 4.52E-02 4.08E-02 FR0200091S003 < 5.62E-02 < 6.42E-02 5.62E-02 FR0200091S004 < 5.52E-02 < 6.05E-02 5.35E-02 FR0200091S005 < 5.02E-02 < 5.32E-02 4.74E-02 FR0200091S006 < 4.86E-02 < 5.9 1E-02 5.1OE-02 FR0200091S007 < 4.09E-02 < 4.42E-02 3.92E-02 FR0200091S008 1.36E-01 3.24E-02 1.45E-01 4.93E-02 1.29E-01 FR0200091S009 < 6.03E-02 < 7.28E-02 6.29E-02 FRO200091SO10 < 5.21 E-02 < 5.67E-02 5.02E-02 FR02000915011 < 4.86E-02 < 5.25E-02 4.66E-02 FR0200091S012 4.14E-01 5.85E-02 4.86E-01 5.03E-02 4.23E-01 FR0200091S013 < 6.70E-02 < 6.48E-02 _ 5.92E-02 FR0200091S014 < 5.18E-02 < 5.87E-02 5.15E-02 FR0200091S015 < 6.26E-02 < 7.29E-02 6.35E-02 FR0200091S016 7.04E-02 3.55E-02 < 9.08E-02 7.73E-02 FR0200091S017 < 6.85E-02 < 8.34E-02 7.19E-02 FR0200091S018 < 6.01 E-02 < 6.68E-02 5.88E-02 FRO200091SO19 < 5.54E-02 < 5.71 E-02 5.131E-02 FR0200091S020 < 5.53E-02 < 5.93E-02 5.27E-02 FR0200091S021 < 6.231E-02 < 5.16E-02 4.92E-02 FR0200091 S022 I .04E-01 3.05E-02 2.83E-01 3.41E-02 2.14E-01 FR0200091S023 4.61E-02 2.50E-02 1.48E-01 3.88E-02 1.09E-01 FR0200091S024 < 4.45E-02 < 4.94E-02 4.35E-02 FR0200091S025 < 6.41 E-02 < 7.21 E-02 6.33E-02 FR0200091S026 < 5.65E-02 < 5.76E-02 5.19E-02 FR0200091S027 < 6.24E-02 < 6.97E-02 6.13E-02 FR0200091S028 < 4.65E-02 < 4.29E-02 3.97E-02 FR0200091S029 < 6.66E-02 < 5.71 E-02 5.39E-02 FR0200091S030 < 5.81 E-02 < 6.06E-02 5.42E-02 FR0200091S031 < 4.55E-02 < 5.15E-02 4.52E-02 FR0200091S032 < 7.36E-02 < 8.43E-02 7.37E-02 FR0200091S033 < 4.86E-02 < 5.65E-02 4.92E-02 FR0200091S034 < 4.91 E-02 < 5.56E-02 4.88E-02 FR0200091S035 < 5.1 IE-02 < 4.82E-02 4.43E-02 FR0200091S036 < 5.91 E-02 < 6.74E-02 5.90E-02 FR0200091S037 < 4.43E-02 < 4.63E-02 4.14E-02 FR0200091S038 < 5.28E-02 < 5.34E-02 4.82E-02 FR0200091S039 < 4.63E-02 < 5.43E-02 4.72E-02 FR0200091S040 < 4.87E-02 < 5.44E-02 4.79E-02 FR0200091S041 < 5.67E-02 < 5.24E-02 4.84E-02 FR0200091S042 < 5.98E-02 < 6.14E-02 5.52E-02 FR0200091S043 < 4.482-02 < 4.882-02 4.32E-02 FR0200091S044 < 5.04E-02 < 6.25E-02 5.37E-02 FR0200091S045 < 4.78E-02 < 5.47E-02 4.78E-02 Mean 6.53E-02 7.76E-02 6.73E-02 Median 5.52E-02 5.76E-02 5.15E-02 Standard Deviation 5.56E-02 7.34E-02 6.14E-02 Range 4.09E-02 to 4.14E-01 4.29E-02 to 4.86E-01 3.92E-02 to 4.23E-01
"<" indicates MDA value. Bold indicates positive detection value FR-0200-09, Revision 0 Page 4 of 21
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 45 soil samples collected, five identified Cs-137 activity below the DCGL value of 4.2 pCi/g and four samples identified Co-60 activity below the DCGL value of 1.5 pCi/g. 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 DCGLs for Cs-137 and Co-60. The average of the unity measurements was 0.067 indicating that the direct measurements averaged 6.7% 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-i 37 value (0.19 pCifg)2 for disturbed soil from the survey unit sample mean activity (0.065 pCi/g). This would equate to an annual dose rate of 0.0 mrem/year.
Taking into account the average residual contamination for Co-60, the annual dose rate would equate to 0.52 mrem/yrj. 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. 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 2).
3 This annual dose is based on LTP Section 6.7, which shows the contaminated soil contribution (for soils contaminated at the DCGL) to be 10 mremly. Therefore, the annual Co-60 dose rate (using the Co-60 DCGL of 1.5 pCifg outside the RA and the mean Co-60 direct activity value of 0.078 pCi/g) would equate to Annual Dose Rate = I 0lx 0 ')0.52 nirem /y.
1.5 FR-0200-09, Revision 0 PageS of2l
- 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 1 survey unit. All of the measurements are below the DCGLs of 4.2 pCi/g (Cs-137) and 1.5 pCi/g (Co-60) for land outside the restricted area.
- 3. A Histogram Plot was also developed. This plot shows a log-normal distribution with two outliers.
- 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 9 was designed, performed, and evaluated in the April 2005-May 2005 time frame. The design was performed to the criteria of the LTP Revision 4 (Reference 1). 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 designation as a Class 1 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 DCGLs of 4.2 pCi/g Cs-137 and 1.5 pCi/g Co-60. 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 two outliers.
FR-0200-09, Revision 0 Page 6 of 21
The scan survey design for this survey unit was developed in accordance with the LTP Revision 4 (Reference 1) 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-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 9 meets the release criteria of 10CFR20.1402 and the State of Maine enhanced criteria.
J. REFERENCES
- 1. Maine Yankee License Termination Plan, Revision 4, February 28th, 2005 provided by Maine Yankee letter to the NRC, MN-05-010
- 2. Maine Yankee Procedure PMP 6.7.8, FSS Data Processing and Reporting, Attachment E, Approach for Dealing With Background Radioactivity for Maine Yankee Final Status Surveys
- 3. Maine Yankee Calculation No. EC-003-04, Use of Canberra In Situ Object Counting System (ISOCS) for FSS Surveys FR-0200-09, Revision 0 Page 7 of 21
Attachment 1 Survey Unit Maps FR-0200-09, Revision 0 Page 8 of 21
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Maine Yankee lMap ID#:FRO200-9 REF Decommissioning Team Maine Yankee DecommissioningProject SuI'ey Form Date: 6/1/05 Survey Type: E Characterization l Turnover N3 Final Status Survey ISurvey Area Name: Yard East Final Status Survey FRO200 SU9 Reference Map
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FR-0200-09, Revision 0 Page IOof 21 FRO200 SU9 Total Survey Unit Area = 1413 sq-m
aine Yankee M. . . . Map ID #: FRO200-9a Decommissioning Team Maine Yankee Decommissionig Project SurbeytFor ae: 5/17/05 Survey Type: O Characterization C] Turnover X Final Status Survey Survey Area Name: Yard East Final Status Survey FRO200 SU9: Yard East ISOCS Scans S001 - S076 407,418.0 N co 2Z 0o I)
I FR-0200-09, Revision 0 Page 11 of 21 Typical ISOCS Spacing (Maximum)
Maine Yankee Map ID#:FRO200-9b Decommissioning Team Iaine Yankee DeconnissionngProjectSurvey ForIu: Date: 5/17105 Survey Type: C Characterization 0 Turnover 0 Final Status Survey I Survey Area Name: Yard East Final Status Survey FRO200 SU9: Yard East Direct Points S001 - S045 FR-0200-09, Revision 0 Page 12 of 21 Surface Area = 1413 sq-m N =40 L=5.9m
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Maine Y'ankee Decomnmissioning .Map Survey Forn ID#:FRO200-9c Project M apI 1 R209 Decommissioning Team I IDate: 5/17/05 Survey Type: El Characterization 0 Turnover SFinal Status Survey Survey Area Name: Yard East Final Status Survey FRO200 SU9: Yard East ISOCS Scans S077 - S100 Excavation Walls 624,109.5E 407,443.5 N 407,418.0 N I
z FR-0200-09, Revision 0 Page 13 of 21
Attachment 2 Survey Unit Instrumentation FR-0200-09, Revision 0 Page 14 of 21
TABLE 2-1 INSTRUMENT INFORMATION ISOCS Detectors (Field Measurements)
Detector No. l MDC (pCi/g) 7607 0.13 to 0.37 7722 0.10 to 0.33 7780 0.14 to 0.38 HIPGe Detectors (Laboratory Analysis)
Detector No. l 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 0.23 to 0.38 pCilg Cs-137 16% DCGL
______ ______ 0.10O to _0.25 _pCilgC o-60 _ _ _ _ _ _ _ _ _ _ _ _ _
4C1.2 pCi/g Co-60 Approved DCGL for land DCGL 4. ~/ s 7 areas outside the Restricted 1.5 pCi/g Co-60 Area (Reference 1)
Investigation Level 1.0 pCi/g Cs-137 (Reference 3)
(ISOCS , 3 m) 0.36 pCi/g Co-60
.6.9 pCi/g Cs-137 DCGL x Area Factor for Class Design DCGLENIC 2.5 pCi/g Co-60 I survey unit, per LTP Section 2.5 pi/g o-60 5.6.3 FR-0200-09, Revision 0 Page 15 of 21
Attachment 3 Investigation Table (No Investigations Required)
FR-0200-09, Revision 0 Page 16 of 21
Attachment 4 Statistical Data FR-0200-09, Revision 0 Page 17 of 21
Survey Package FRO200 Unit 9 UNITY Soil Sign Test Summary
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Survey Package: FR0200 Survey Unit: 09 Evaluator: Andy Olsen DCGLW: 1.OOE+00 Unity DCGL=: 1.70E+00 AF = 1.7 LBGR: 5.OOE-01 Sigma: 3.20E-01 (1.33 pCilg /4.2 pCig)
Type I error: 0.05 Type II error: 0.05 Nuclide: UNITY Soil Type: N/A
~ ~ ~ ~~-~orments Zo: 1.645 ZI: -, 1.645 Sign p: 0.933193 Calculated Relative Shift: 1.5 Relative Shift Used: 1.5 Uses 3.0 if Relative Shift is >3 N-Value: 15 N-Value+20%: 18
' Sarp e,Data',Values i t ; ; ornments-t Number of Samples: 45 Median: . 5.15E-02 Mean: 6.73E-02 Net Sample Standard Deviation : 6.14E-02 Total Standard Deviation: ' :6.14E-02 Sum of samples and reference Maximum: - '4.23E-01
,n:,W,-l;.SnTdst ResuitX . AI a;i:'nns Adjusted N Value: - 45 S+ Value: 45 Critical Value: :.' : 28 Sign test results: ,:.: Pass rit i~s 'rCiterac-atis~-ton en<' 'I?,'
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Sufficient samples collected: - ;" Pass Maximum value <DCGL,: Pass Median value <DCGLW: Pass Mean value <DCGLg, -Pass Maximum value <DCGLe=:, -Pass Total Standard Deviation <=Sigma: Pass Criteria comparison results: a;ad .' .' Pass F;eialStatu- -
The survey unit passes all conditions: Pass Survey Unit Passes FRO200-SU9-SoilSign-UN1TY.xts FR-0200-09, Revision 0 5 8:35 AM Page 18 of 21
FRO200 SU-9 Quantile Plot 0.50 0.40 - I.
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- Activity WC (unitized)
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One-Sample T-Test Report Page/Date/Time 2 5/24/05 2:15:56 PM Database C:\Program Files\NCSS97\FRO200 SU-9.SO Variable C2 Plots Section Histogram of FR-0200, SU-9 50, Cu a) 38 E
cn o 25 E
Z 13 0.660 ' .1 13 .0.225 0.338 . . .450 Activity (unitized]
FR-0200-09, Revision 0 Page 20 of 21
One-Sample T-Test Power Analysis Page/Date/Time 2 5/24/05 2:16:51 PM Chart Section Retrospective Power Curve 1.0- .
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0.0 0.2 0'4 0'6 0.8 1.0 Survey Unit Mean (unitized)
FR-0200-09, Revision 0 Page21 of 21