ML050590060

Final Status Survey Release Record FR-0100 RCA Yard West Survey Unit 2

ML050590060
Person / Time
Site:	Maine Yankee
Issue date:	02/17/2005
From:	Donna Anderson, Cooper W, Dockins L, Packer J, Pillsbury G Maine Yankee Atomic Power Co
To:	Document Control Desk, NRC/FSME
References
FR-0100-02, Rev 0
Download: ML050590060 (27)

Text

MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-O100 RCA YARD WEST SURVEY UNIT 2 Prepared By: Ž c Date: .a / /as FSS Engineer - Signature 2). A~E75AJ Printed Name Reviewed By: d&c e Date: lv / o 5 l Spatlist - Signature Printed Name Reviewed By: __Datc: Date: 2_ 5-Independent Review - Signature Prited ame Approved By: Date:

d NmSignature Printed Varne Approved By: A , ,Date: -Zl 7Z.

FSS, MOP - Signature 7 Printed Name Revision 0

MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0100 RCA YARD WEST SURVEY UNIT 2 A. SURVEY UNIT DESCRIPTION FR-0100 RCA Yard West Survey Unit 2 occupied the southeast corner of the original Restricted Area "backyard." The 1,558 m2 area was previously excavated to remediate the contaminated soil and the remaining terrain surveyed under final survey packages FR-01 I I Survey Units 3, 4 and 7. Following final survey of the excavations, the area was backfilled to grade (approximate 20-ft. El.). The southwest portion of this survey unit slopes gently towards the old Forebay area. FR-0I 00 Survey Unit 2 is located at coordinates 407,400N and 623,800E, using Maine State Coordinate System (West Zone) NAD 1927. The location of the survey unit in relation to the former Containment Building and the surrounding FR-01 00 survey units is shown on Map FROI 00U2-SITE (Attachment 1).

B. SURVEY UNIT DESIGN INFORMATION The survey unit was designated a Class I land survey per the LTP (Table 5-1 C) and 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. A decision to use E-600/SPA-3 instrumentation for scan surveys in Survey Unit 2 affected the number of direct measurements to be performed due to the scan MDC of the instrumentation (5.9 pCi/g Cs-1 37, per LTP Table 5-6). The DCGL for soils inside the Restricted Area was limited to 2.39 pCi/g Cs-I 37. The data quality objective for the scan MDC of open land areas is to identify areas of significant elevated activity, i.e., those exceeding the DCGLE?,Mc. To obtain a DCGLEMc of 6 pCi/g Cs-1 37, which is greater than the E-600/SPA-3 scan MDC, an Area Factor of 2.5 (6 pCi/g --2.39 pCi/g DCGL = 2.5) is required. From LTP Table 6-12, the sample area corresponding to an area factor of 2.5 is approximately 11 m2 . Therefore, the total area of 1,558 m2 divided by a sample area of 11 m required a minimum of 142 samples.

Because the measurement locations were based on a systematic square grid with a random start point, the N=142 design led to a survey unit map with 154 locations. The direct point locations are illustrated on map FROIOOU2-DIRT (Attachment 1). Direct measurements (soil samples) were collected from required locations and analyzed with laboratory gamma spectroscopy instrumentation.

The Class I survey unit required scans covering 100% of the 1,558 m2 area in accordance with LTP Table 5-3. E-600/SPA-3 instrumentation was used to perform the gamma scans.

Equal size grids measuring 1.71 m by 5.83 m (approximately 10 in2 ) were established.

Configuration of the 156 survey scans are shown on map FROI OOU2-SCAN (Attachment 1).

Background values were established based on local scaler values in the survey unit. These background values were used to determine scan alarm setpoints and to divide the scan grids into 4 different background groups, as shown on FROIOOU2-Areas. The alarm setpoints were established to confirm the scan MDCs used were appropriate.

FR-0 100-02, Revision 0 Page 2 of 27

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 DCGLE1,C. As discussed above, an EMC sample size adjustment was made to provide a high level of confidence that elevated areas could be detected by the scan process.

TABLE I SURVEY UNIT DESIGN PARAMETERS Survey Unit Design Criteria Basis Area 1,558 m 2 Class 1,< 2,000m 2 Number of Direct Based on investigation level of Muments Reqr 142 6 pCi/g, AF 2of 2.5 and a sample Measurements Required area of 11 in .

Sample Area im2 1,558 m 2 / 142 = 11 m 2 Sample Grid Spacing 3.3 in (1 lI2 Scan Grid Area I ml2 < lo m2

2. Based on investigation level of Area F6 pCi/g and a DCGL of 2.39 pCi/g Scan Area 1,558 m2 Class I Area - 100%

Background _______________________;_____________________

9,823 cpm Group I SPA-3 10,762 cpm Group 2 12,000 cpm Group 3

. 9,357 cpm Group 4 Scan Investigation Level 3 Sigma of Background Reference 7 Scan_______________Level plus Background See Table 2-2, Attachment 2 DCGL 20.86 pCi/g Co-60 l References 4 and 8 Design DCGLENIC 6.0 pCi/g Cs-137 DCGL x Area Factor for Class I Design ______ 2.15 pCi/g Co-60 survey unit, tion 5.6.3 C. SURVEY RESULTS A total of 154 direct measurements were performed in Survey Unit 2. The results are presented in Table 2. All direct measurements were below the DCGL.

E-600/SPA-3 gamma scans were performed in 156 grids. A total of 17 verified alarms were received during the soil scans. In addition, I grid (S024) with a higher than expected background measurement was not scanned during the initial survey. As a result, a total of 18 grids were investigated using survey investigation package XR 0100-02. The investigation results are discussed in Section D.

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TABLE 2 DIRECT MEASUREMENTS Cs-137 Uncertainty Co-60 Uncertainty Unitized Sample Number (pCi/g) (Pcilg) (pCilg) (pCilg) Unay uleo FRO100021SO0I < 4.101E-02 T < 4.7613-02 l 7.25E-02 FR0100021S002 < 4.76E-02 l < 5.311E-02 8.1713-02 FR0100021S003 < 4.2313-02 < 4.4513-02 6.94E-02 FRO100021SO04 < 3.90E-02 < 4.13E-02 6.43E-02 FR0100021S005 < 4.42E-02 _ < 4.6713-02 7.2813-02 FRO100021S006 < 4.5313-02 < 5.511E-02 8.3013-02 FRO100021S007 < 4.0613-02 l < 4.2 11E-02 6.5913-02 FRO100021SO08 < 3.81E-02 < 4.03E-02 6.2813-02 FRO100021SO09 < 4.1513-02 < 4.87E-02 7.4013-02 FRO100021SO10 < 3.7913-02 < 4.2513-02 6.53E-02 FR0100021SOII < 4.81 E-02 < 4.41E-02 7.1413-02 FR0100021S012 < 3.8013-02 < 4.15E-02 6.4213-02 FR0100021S013 < 3.7513-02 < 4.2613-02 6.52E-02 FR0100021SO14 < 3.511E-02 < 3.7813-02 5.8613-02 FR0100021S015 < 3.9813-02 l < 3.8513-02 6.1413-02 FRO100021SO16 < 3.57E-02 < 4.5013-02 6.7313-02 FRO100021SO17 < 4.3413-02 l < 5.2313-02 7.90E-02 FRO100021SO18 < 4.7013-02 < 5.03E-02 7.8213-02 FRO100021SO19 < 4.7613-02 l < 5.2513-02 8.10E-02 FRO100021S020 < 4.42E-02 < 4.1713-02 6.70E-02 FR0100021S021 < 4.0413-02 < 4.5013-02 6.9213-02 FRO100021S022 < 5.68E-02 < 6.711E-02 1.0213-0I FR0100021S023 < 3.7713-02 < 4.0513-02 6.2913-02 FR0100021S024 < 4.3813-02 < 4.2713-02 6.8013-02 FR0100021S025 < 3.6613-02 < 4.70E-02 7.0013-02 FRO100021S026 < 3.72E-02 < 4.87E-02 7.2213-02 FRO100021S027 < 3.6413-02 < 4.3013-02 6.52E-02 FR0100021S028 < 4.17E-02 l < 4.3213-02 6.77E-02 FRO100021S029 < 4.96E-02 < 5.2213-02 8.1513-02 FRO100021S030 < 3.99E-02 < 4.8013-02 7.2513-02 FRO100021S031 < 4.34E-02 < 5.1 IE-02 7.76E-02 FR0100021S032 < 4.78E-02 < 4.72E-02 7.49E-02 FR0100021S033 < 4.10OE-02 < 4.7413-02 7.2313-02 FRO100021S034 < 3.9413-02 l < 4.0913-02 6.4013-02 FR0100021SO35 < 4.1213-02 < 4.3913-02 6.83E-02 FR0100021S036 < 3.6813-02 < 3.4413-02 5.54E-02 FR0100021S037 < 4.3713-02 < 4.70E-02 7.29E-02 FR0100021SO38 < 3.9213-02 < 4.3213-02 6.6613-02 FR0100021S039 < 3.96E-02 < 4.69E-02 7.111E-02 FRO100021SO40 < 3.68E-02 < 4.25E-02 6.4813-02 FRO100021SO41 < 5.2213-02 < 5.36E-02 8.42E-02 FR-0100-02, Revision 0 Page 4 of 27

Cs-137 Uncertainty Co-60 Uncertainty Unitized Samplc Number (pCi/g) (pCi/g) (pCi/g) (pCi/g) Unity Rule FR0100021S042 < 4.07E-02 < 4.54E-02 6.98E-02 FR0100021S043 < 4.19E-02 < 4.90E-02 7.45E-02 FR0100021S044 < 4.46E-02 < 5.02E-02 7.70E-02 FR0100021S045 < 4.28E-02 < 4.41E-02 6.92E-02 FR0100021S046 < 4.14E-02 < 4.72E-02 7.22E-02 FR0100021S047 < 4.37E-02 < 5.06E-02 7.71E-02 FR0100021S048 < 4.41E-02 < 4.91E-02 7.55E-02 FR0100021S049 < 5.35E-02 < 5.31E-02 8.41E-02 FRO100021SO50 1.24E-01 3.42E-02 < 5.77E-02 l.19E-01 FRO100021SO51 < 5.28E-02 < 5.51E-02 8.62E-02 FR0100021S052 < 4.24E-02 < 4.83E-02 7.39E-02 FR0100021S053 < 4.94E-02 < 4.49E-02 _ 7.29E-02 FR0100021S054 < 4.02E-02 < 4.1OE-02 6.45E-02 FR0100021S055 1.41E-01 3.611E-02 < 5.1OE-02 1.18E-01 FR0100021S056 1.22E-01 3.41 E-02 < 4.96E-02 1.09E-01 FR0100021S057 < 4.39E-02 < 4.84E-02 7.46E-02 FR0100021S058 < 3.97E-02 < 4.78E-02 _ 7.22E-02 FR0100021S059 < 4.3 11E-02 < 5.2013-02 7.85E-02 FR0100021S060 < 4.75E-02 < 4.87E-02 7.65E-02 FR0100021S061 < 4.40E-02 < 4.80E-02 7.42E-02 FR0100021S062 < 4.86E-02 < 4.28E-02 7.0 1E-02 FR0100021S063 < 5.48E-02 < 5.2213-02 8.36E-02 FR0100021S064 6.83E-02 2.80E-02 < 5.46E-02 9.21E-02 FR0100021S065 1.21E-01 3.4413-02 < 5.76E-02 1.17E-01 FR0100021S066 < 4.50E-02 < 4.55E-02 7.17E-02 FR0100021S067 < 4.15E-02 < 4.66E-02 _ 7.1613-02 FR0100021S068 9.24E-02 3.35E-02 < 5.56E-02 1.03E-01 FR0100021S069 1.23E-01 3.48E-02 < 5.10E-02 1.1 E-01 FRO100021S070 7.58E-02 2.58E-02 < 4.99E-02 8.98E-02 FRO100021SO71 < 4.53E-02 < 4.49E-02 7.12E-02 FR0100021S072 < 4.73E-02 < 6.23E-02 9.22E-02 FR0100021S073 < 4.58E-02 < 4.56E-02 7.22E-02 FR0100021S074 < 4.23E-02 < 4.45E-02 6.94E-02 FR0100021S075 < 4.93E-02 < 5.22E-02 8.13E-02 FR0100021S076 < 5.28E-02 < 5.99E-02 9.17E-02 FR0100021S077 6.86E-02 3.43E-02 < 4.91E-02 8.58E-02 FR0100021S078 1.11E-01 2.56E-02 < 4.77E-02 1.02E-01 FR0100021S079 8.98E-02 2.85E-02 < 4.84E-02 9.39E-02 FRO100021SO80 1.51E-01 3.19E-02 < 4.80E-02 I.19E-01 FRO100021SO81 < 4.20E-02 < 4.36E-02 6.83E-02 FR0100021S082 < 4.511E-02 < 6.08E-02 8.96E-02 FR0100021S083 8.44E-02 2.81E-02 < 4.64E-02 _ 8.93E-02 FR0100021S084 < 5.61E-02 < 4.75E-02 7.87E-02 FR0100021S085 < 3.85E-02 < 4.41E-02 6.74E-02 FR0100021S086 < 4.17E-02 < 4.57E-02 7.06E-02 FR0100021S087 < 4.17E-02 < 4.43E-02 6.90E-02 FR-O100-02, Revision 0 Page 5 of 27

Cs-137 Uncertainty Co-60 Uncertainty Unitized Samle Number (pCi/g) (pCi/g) (pCilg) (pCi/g) Valun ofu FRO100021SO88 < 4.41E-02 < 4.21E-02 _ 6.74E-02 FR0100021S089 < 4.72E-02 < 4.67E-02 7.41E-02 FRO100021SO90 1.07E-01 3.33E-02 < 4.56E-02 9.79E-02 FR0100021S091 < 4.47E-02 < 4.66E-02 7.29E-02 FR0100021S092 1.48E-01 2.99E-02 < 4.98E-02 1.20E-OI FR0100021S093 1.03E-01 3.07E-02 < 5.04E-02 1.02E-OI FR0100021S094 1.12E-01 3.08E-02 < 5.82E-02 1.15E-OI FR0100021S095 1.41E-01 3.07E-02 < 4.65E-02 1.13E-OI FR0100021S096 1.86E-01 3.70E-02 < 5.92E-02 1.47E-OI FR0100021S097 1.49E-01 3.51E-02 < 5.06E-02 1.21E-OI FR0100021S098 < 5.26E-02 < 4.78E-02 7.76E-02 FR0100021S099 < 3.90E-02 < 4.66E-02 7.05E-02 FRO10002IS100 < 4.43E-02 < 4.72E-02 7.34E-02 FRO100021S101 < 3.77E-02 < 4.06E-02 6.30E-02 FRO100021S102 < 4.26E-02 < 4.19E-02 6.65E-02 FRO10002IS103 < 4.52E-02 < 4.37E-02 6.97E-02 FRO10002IS104 < 4.57E-02 < 4.22E-02 6.82E-02 FRO100021SIOS < 6.1IE-02 < 5.12E-02 8.51E-02 FRO100021SIO6 8.09E-02 3.1 1E-02 < 5.44E-02 9.71E-02 FRO10002IS107 1.O1E-O1 2.86E-02 < 4.39E-02 . 9.32E-02 FRO100021S108 1.51E-01 3.80E-02 < 6.03E-02 . 1.33E-Ol FRO10002IS109 1.20E-01 2.60E-02 < 4.72E-02 . l.05E-O1 FRI00021 SIIO 1.92E-01 3.6613-02 < 5.66E-02 1.46E-01 FRI000021SI il 1.94E-01 3.47E-02 < 5.5213-02 1.4513-01 FR0100021S1 12 < 4.6013-02 < 5.26E-02 8.04E-02 FR0100021S1 13 1.66E-01 4.40E-02 1.57E-01 3.2613-02 2.5213-01 FRO 100021S1 14 2.51 E-01 3.8313-02 1.85E-01 2.70E-02 3.20E-O0I FR0100021S115 8.94E-02 3.57E-02 < 6.71 E-02 1.15E-O1 FR0100021S1 16 < 4.69E-02 < 4.42E-02 7.10E-02 FRO100021S117 < 5.56E-02 < 5.18E-02 8.35E-02 FRO10002IS118 8.52E-02 2.59E-02 < 5.0813-02 9.47E-02 FRO10002ISI19 < 5.0213-02 < 4.6613-02 7.52E-02 FRO10002IS120 1.04E-01 3.27E-02 < 5.82E-02 1.1IE-O1 FRO10002IS121 1.63E-01 3.2913-02 < 5.21E-02 1.29E-01 FR0100021S122 1.16E-01 3.28E-02 < 5.4813-02 1.12E-OI FR0100021S123 1.22E-01 3.65E-02 < 4.75E-02 1.06E-OI FR0100021S124 3.72E-01 4.83E-02 < 5.16E-02 2.16E-01 FR0100021S125 2.14E-01 3.6413-02 < 4.67E-02 1.44E-O1 FR0100021S126 1.25E-01 2.9813-02 < 5.05E-02 1.1 IE-OI FR0100021S127 134E-01 3.27E-01 < 6.33E-02 1.30E-01 FR0100021S128 1.48E-01 3.48E-02 < 5.99E-02 1.32E-01 FR0100021S129 1.51E-01 3.29E-02 < 5.07E-02 1.22E-01 FRO100021S130 < 5.99E-02 < 4.7213-02 7.99E-02 FRO10002IS131 6.84E-02 2.39E-02 < 4.50E-02 8.1OE-02 FR0100021S132 < 5.98E-02 < 5.23E-02 8.5813-02 FR0100021S133 1.15E-01 3.33E-02 < 5.86E-02 1.613-01I FR-O 100-02, Revision 0 Page 6 of 27

Cs-137 Uncertainty Co-60 Uncertainty Unitized Sample Number (pCi/g) (pCi/g) (pCi/g) (pCi/g) Unity fule FR0100021S134 9.08E-02 2.56E-02 < 4.69E-02 9.2513-02 FR0100021S135 1.61E-01 3.12E-02 < 4.86E-02 1.24E-01 FR0100021S136 *1.74E-01 3.7513-02 < 5.1813-02 1.33E-01 FR0100021S137 1.57E-01 3.7313-02 < 5.0513-02 1.24E-01 FR0100021S138 1.15E-01 2.98E-02 < 5.3613-02 1.IIE-OI FR0100021S139 1.32E-01 3.36E-02 < 6.99E-02 1.36E-01 FRO10002IS140 8.82E-02 3.1OE-02 < 5.53E-02 I.OIE-01 FRO10002IS141 < 6.05E-02 < 6.3413-02 9.90E-02 FR0100021S142 1.18E-01 3.43E-02 < 5.2813-02 .I1 E-01 FR0100021S143 1.59E-01 3.30E-02 < 5.7713-02 1.34E-0l FR0100021S144 3.OOE-01 4.28E-02 < 5.76E-02 1.93E-01 FR0100021S145 1.23E-01 3.12E-02 < 5.1313-02 1.1 IE-01 FR0100021S146 1.13E-01 2.85E-02 < 4.34E-02 9.79E-02 FR0100021S147 9.76E-02 3.36E-02 < 5.28E-02 1.03E-01 FR0100021S148 l.lOE-01 2.72E-02 < 4.93E-02 1.03E-01 FR0100021S149 1.28E-01 3.26E-02 < 5.20E-02 1.1413-01 FRO10002iS150 1.58E-01 3.2313-02 < 4.86E-02 1.23E-0I FRO10002IS151 1.24E-01 3.0513-02 < 4.5313-02 1.04E-01 FRO10002IS152 9.36E-02 3.37E-02 < 4.97E-02 9.69E-02 FR0100021S153 7.42E-02 2.93E-02 < 4.68E-02 8.5413-02 FR0100021S154 6.75E-02 2.89E-02 < 5.28E-02 8.96E-02 Mean 7.96E-02 5.08E-02 9.24E-02 Median 4.95E-02 4.84E-02 8.11E-02 Standard Deviation 5.48E-02 1.52E-02 3.42E-02 Range 3.51E-02 to 3.72E-01 3.44E-02 to 1.85E-O1 5.54E-02 to 3.20E-01

"<"indicates MDA value. Bold indicates positive detection value.

D. SURVEY UNIT INVESTIGATIONS PERFORMED AND RESULTS Soil scans performed with the E-600/SPA-3 during final surveys identified 17 scanned grids with verified alarms. In addition, one grid (S024) with a higher than expected background was not scanned during the initial final survey effort. An investigation package was written to perform additional scans within the identified grids with verified alarms, mark and log each verified alarm and collect a soil sample at the highest verified alarm location. Locations of grids that required investigations are provided on XROlOOU2-SCAN (Attachment 1).

FR-0 100-02, Revision 0 Page 7 of 27

During the investigation effort, 8 of the investigated grids received excessive E-600/SPA-3 alarms. A second investigation package was written to perform the gamma scans using an in situ gamma spectroscopy detector (ISOCS). Twvo ISOCS scans were performed within each scan grid that had received excessive alarms as well as grid S024, which was not previously scanned. The ISOCS detector was positioned perpendicular to the surface at a 2-meter distance, using a 90-degree collimator, to provide a 12 m 2 field of view. Configuration of the ISOCS scans are provided on XROIOOU2-SCAN2. ISOCS gamma scans were performed at 18 locations using an investigation level of 2.2 pCi/g Cs-137 and 0.80 pCi/g Co-60. The gamma scans were performed for a sufficient count time to achieve a Minimum Detectable Activity (MDA) of less than 25% of the DCGL. All scan activity levels were below the MDAs which were below the prescribed investigation levels. In addition to the ISOCS gamma scans, E-600/SPA3 scans were performed within each grid to identify the location of highest activity and a soil sample collected from that location.

As a result of the investigations, a total of 18 soil samples were collected. Results of the soil samples are presented in Table 3-1 (Attachment 3). Two samples identified Co-60 below the DCGL while 9 samples identified Cs-l 37 below the DCGL. All other sample activities were below the MDA. In addition, the maximum reported unity value was less than 35% of the unitized DCGL.

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. Of the 154 soil samples collected, 62 identified Cs-137 activity below the DCGL value of 2.39 pCi/g while only 2 samples identified Co-60 activity below the DCGL value of 0.86 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 DCGL for both Co-60 and Cs-l 37.

The average of the DCGL unity fractions was 0.0924 and the maximum reported unity value was less than 35% of the unitized DCGL.

Of the 18 investigation soil samples collected, 2 identified Co-60 below the DCGL while 9 identified Cs-137 activity below the DCGL. The average of the DCGL unity fractions was 0.119 and the maximum reported unity value was 34.8% of the unitized DCGL.

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)l for disturbed soil from the survey unit sample mean activity (0.0796 pCi/g). The net result is negative and would equate to an annual dose rate of 0.0 mrem/year. Taking into account the average residual contamination level for Co-60, the annual dose rate would equate to 0.33 mrem/year 2 . However, for purposes of demonstrating compliance with the radiological criteria for license termination and the enhanced State criteria, background activity was not subtracted from the sample analysis activity values.

See Attachment E to Maine Yankee Procedure PMP 6.7.8 (Reference 5).

2 This annual dose equivalent is based on LTP Table 6-11 which shows the RA contaminated soil contribution (for surface soils contaminated at the DCGL) to be 5.63 mrem/y. Therefore, the annual dose rate would equate (0.0508" to Annual Dose Rate = 5.63 x ) = 033mremly FR-0100-02, Revision 0 Page 8 of 27

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, llistogram, 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. 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 value 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 well below the DCGLs of 2.39 pCi/g for Cs-137 and 0.86 pCi/g for Co-60 for land inside the restricted area.,

3. A Histogram Plot was also developed based on the unity values. This plot shows a log-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.

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.

FR-0 100-02, Revision 0 Page 9 of 27

II. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit 2 was designed, performed, and evaluated in the December 2004 and January 2005 time frame. The design was performed to the criteria of the LTP Revision 3 (References 2 and 4). LTP Change No.05-001 (Reference 8) 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 resulted in an increased dose rate of 2.04 mrem.y from RA contaminated soils at depths greater than 15 cm. The LTP change directly impacted the retrospective dose calculation portion of release records dealing with Restricted Area excavations that were necessitated by radiological remediation.

FR-0100-02 consists of surface soils that cover the excavations previously surveyed under FR-01 11 Survey Units 3, 4, and 7. The Deep Soil dose for underlying soils was accounted for in the release records of the FR-01I I packages. As a result, the retrospective dose determination for FR-0100 Survey Unit 2 was based only on the contribution from surface soils within the top 15 cm. 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 DCGLs of 2.39 pCi/g Cs-137 and 0.86 pCi/g Co-60.

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.

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. An EMC sample size adjustment was made to provide a high level of confidence that elevated areas could be detected by the scan process. Scans performed with E-600/SPA-3 instrumentation resulted in 17 verified alarms. An investigation was conducted via package XR 0100-02 and 18 additional direct measurements were obtained. All direct measurements were less than the DCGLs of 2.39 pCi/g Cs-137 and 0.86 pCi/g Co-60.

It is concluded that FR 0100 Survey Unit 2 meets the release criteria of I OCFR20.1402 and the State of Maine enhanced criteria.

FR-0100-02, Revision 0 Page 10 of 27

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 Procedure 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 (MY), Use of In Situ Object Counting System (ISOCS) for FSS Surveys

7. Maine Yankee Calculation No. EC 009-01 (MY), Instrumentation Selection and MDC Calculation

8. Maine Yankee LTP Change No.05-001, Deep Soil Co-60 DCGL FR-0100-02, Revision 0 Page 11 of 27

Attachment 1 Survey Unit Maps FR-0100-02, Revision 0 Page 12 of 27

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FR-01 00-02, Revision 0 Page 14 of 27

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[ Group 4: 8,357 to 10,357 cpm FR-0100-02, Revision 0 Page 16of27

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Attachment 2 Survey Unit Instrumentation FR-O100-02, Revision 0 Page 19 of 27

TABLE 2-1 INSTRUMENT INFORMATION E-600 S/N SPA-3 Probe S/N 2488 725890 2490 726554 1645 2253 2619 2254 2489 726554 2491 2254 ISOCS Detectors (Field Measurements)

Detector No. l MDC (pCi/g) 7780 l 0.14 to 0.3 HPGc Detectors (Laboratory Analysis)

Detector No. MDC (PCi/g)

FSSI 0.03 to 0.07 FSS2 0.03 to 0.07 TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, INVESTIGATION LEVEL AND DCGLENec Parameter Comments Scan MDC (E-600/SPA-3) 5.9 pCi/g Design Scan MDC,

___LTP Table 5-6 (Reference 1)

Scan MDC (ISOCS) 0.14 to 0.30 pCi/g < 25% DCGL 2.39 pCi/g Cs-137 Approved DCGL for Area, land areas DCGL DCGL0.8 p~ig Co-60 0.86 pCi/g C-60(References inside the Restricted 4 and 8)

E-600/SPA-3 12,126 (Group I)

Investigation Level 13,173 (Group 2)

(Alarm Setpoint) 14,546 (Group 3)

(cpm) 11,604 (Group 4)

Investigation Level 2.2 pCi/g Cs-137 Reference 6 (ISOCS i, 2 m) 0.8 pCi/g Co-60 l__eference_6 Design DCGLENc 6.0 pCi/g Cs-137 DCGL x Area Factor for Class I Design DCGL___c 2.15 pCi/g CO-60 survey unit, per LTP Section 5.6.3 NOTE: ISOCS scan MDCs were adjusted based on a thin layer of snow within the survey unit. As a conservative measure, a snow layer equivalent to 2 inches of water was added to the ISOCS configuration to determine the resulting instrument MDCs. The ISOCS MDCs in Tables 2-1 and 2-2 reflect the conservative adjustment.

FR-0100-02, Revision 0 Page 20 of 27

Attachment 3 Investigation Table FR-O 100-02, Revision 0 Page 21 of 27

TABLE 3-1 INVESTIGATION TABLE XRO100-02 INVESTIGATION SOIL SAMPLING RESULTS Initial Alarm Invest. Invest. Unitized Elevated Grin Scan Setpoint Scan Scaler Cs-137 Uncertainty Co-60 Uncertainty Value of DCGL Sample Location Value S(cpr) Value Value (pCi/g) (pCi/g) (pCi/g) (pCi/g) Vale Comparison (cpm) (cpm) (cpm)

XR0100021SO05 13,400 13,173 < 13,173 10,810 1.16E-01 2.92E-02 < 4.96E-02 1.06E-0I < DCGL XR0100021S007 12,080 11,604 (ISOCS) N/A 3.77E-01 4.88E-02 < 5.19E-02 2.18E-0I < DCGL XR0100021S024 HB 13,173 (ISOCS) N/A 1.28E-01 2.95E-02 < 4.25E-02 1.03E-01 < DCGL XR0100021S027 13,250 11,604 (ISOCS) N/A 3.73E-01 4.97E-02 1.65E-01 2.72E-02 3.48E-01 <DCGL XR0100021S028 12,500 11,604 (ISOCS) N/A 1.71E-01 3.78E-02 1.71E-01 4.31E-02 2.71E-01 < DCGL XR0100021SO30 12,010 11,604 (ISOCS) N/A 1.28E-01 3.05E-02 < 5.84E-02 1.22E-01 < DCGL XR0100021S035 11,610 11,604 11,920 10,640 8.12E-02 2.51E-02 < 4.72E-02 8.89E-02 < DCGL XR0100021S053 18,600 12,126 13,080 11,210 < 4.52E-02 < 4.71E-02 7.37E-02 < DCGL XR0100021S054 13,990 12,126 11,220 10,820 < 3.97E-02 < 4.21E-02 6.56E-02 < DCGL XR0100021S072 12,090 11,604 (ISOCS) N/A 1.56E-01 3.09E-02 < 5.06E-02 1.24E-01 < DCGL XR0100021S095 12,440 12,126 12,280 10,490 1.19E-01 3.21E-02 < 5.51E-02 1.14E-01 < DCGL XR0100021S099 12,470 11,604 (ISOCS) N/A < 5.13E-02 < 5.45E-02 8.48E-02 < DCGL XR0100021S100 12,120 11,604 (ISOCS) N/A < 4.56E-02 < 5.27E-02 8.04E-02 < DCGL XR0100021S1O1 12,180 11,604 (ISOCS) N/A < 4.68E-02 < 4.83E-02 7.57E-02 < DCGL XR0100021S116 12,970 12,126 11,850 11,400 < 3.99E-02 < 4.18E-02 6.53E-02 < DCGL XR0100021S129 12,600 12,126 13,360 13,310 <4.32E-02 < 4.39E-02 6.91E-02 < DCGL XR0100021S143 13,510 12,126 11,990 10,170 <3.74E-02 j< 4.30E-02 _ 6.56E-02 < DCGL XR0100021S145 13,100 12,126 11,650 10,260 < 3.78E-02 I< 4.38E-021 6.67E-02 < DCGL

_ Survey Unit Mean / DCGL 0.0924 Total 0.0924 NOTE: l. "<" indicates value less than MDA, MDA value is reported.

2. HB indicates high background.

FR-0100-02, Revision 0 Page 22 of 27

Attachment 4 Statistical Data FR-0 100-02, Revision 0 Page 23 of 27

Survey Package FRO100 Unit 2 UNITY Soil Sign Test Summary "iibi~i~6 Values, Survey Package: FRO100 RCA Yard West Survey Unit: 02 Evaluator: DA DCGLw: 1.OOE+00 Unity DCGL.,n: 2.50E+00 AF x Unity LBGR: 5.00E-01 50% of DCGL Sigma: 5.56E-01 Unitized (1.33 pCi/g /2.39 pCi/g)

Type I error: 0.05 Type II error: 0.05 Nuclide: UNITY Soil Type: N/A Z,,- 1.645 ZI.P: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 f~~".: ~ "";Comments.f>fy4' Number of Samples: ' 154 Median: 8.11 E-02 Mean: 9.24E-02 Net Sample Standard Deviation: 3.42E-02 Total Standard Deviation: 3.42E-02 Maximum: 3.20E-01

+iis -SnTest Results'; 1-wWi!u. .. r;.W~tlt'; ^-9>Comments~t5 .r: :.1a>J Adjusted N Value: 154 S+ Value: 154 Critical Value: , -; . '87 Sign test results: - - . Pass Sufficient samples collected: Pass Maximum value <DCGL:; Pass Median value <DCGL,:, Pass Mean value <DCGLv,: ,Pass Maximum value <DCGLemc: Pass Total Standard Deviation <=Sigma: ,!;' i Pass Criteria comparison results: . I-, Y.. . Pass The survey unit passes all conditions: ;- . IPass urvey unit Passes FRO100-SU2-SoilSign-UNITY.xAs 1128/05 8:38 AM FR-0100-02, Revision 0 Page 24 of 27

FR-0100 SU-2 Quantile Plot 0.350 4-0.300 0.250

~j 0

0 0.200 tA- C.)

• Activity 0.150 -_~unitzed)

(edian "0 (unitized) 0.100 a"A=a1 111111160 ..

!!! mim" 0.050 0.000 i I i i I 0 25 50 75 100 Percent

One-Sample T-Test Report PagelDate/Time 2 1/26/05 11:12:05 AM Database Variable C2 Plots Section Histogram of FR-01 00, SU-2 120 U,

C) 90 E

co 60 0

E 30 I

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0.6iO5 0.125 .. 206 0.275 0.350 Activity (unitized)

FR-0 100-02, Revision 0 Page 26 of 27

One-Sample T-Test Power Analysis Page/Date/Time 2 1/26/05 11:13:18 AM Chart Section Retrospective Power Curve 1.0 - -

I I

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FR-0100-02, Revision 0 Page 27 of 27