ML043640293

Maine Yankee Final Status Survey Release Record FR-0400 Forebay Survey Unit 4

ML043640293
Person / Time
Site:	Maine Yankee
Issue date:	12/22/2004
From:	Cooper W J, Pillsbury G, Randall D B, Tozzie N Maine Yankee Atomic Power Co
To:	NRC/FSME
References
MN-04-060, RA-04-118 FR-0400-04, Rev 0
Download: ML043640293 (23)

Text

MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0400 FOREBAY SURVEY UNIT 4 Date: Prepared By: , / -og -ate FSS Engineer -Signature D1 l e A4 AtI" IIa ,PrnYd Name Date: Reviewed By: I / ( Dae/FSS Sp6igatigurature S nnzn ,/Printed Name Date: Revieved By: Signature/,Printed

!]lc Approved By: l~X 3 Iate//Stipi inienden+

e intr Printed Name i'Date: Approved By:is 2 /Zo/SS, AIOP -Signature Printed Name MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0400 FOREBAY SURVEY UNIT 4 A. SURVEY UNIT DESCRIPTION Survey Unit 4 is located within Survey Area FR-0400, the Forebay. The Forebay is located south of the radiologically Restricted Area of the site at coordinates 407,000 N and 623,600 E (see map FR 0400 SITE, Attachment 1). The Forebay is a large, rock-lined basin in which condenser cooling water collected prior to its release through the diffuser system out to the ocean. During plant operation the Forebay/Diffuser System was the licensed discharge path for liquid, radiological effluent.

After plant shutdown, stop logs were set in place at the Forebay end of the diffuser to isolate the Forebay in order to prevent the release of Forebay sediment into the river during remediation activities.

Two earthen dikes make up the north-south running walls of the Forebay with concrete walls at the extreme north and south ends to support the circulating water and diffuser pipes. The dike walls form a V at the southern end of the Forebay (adjacent to Foxbird Island). The diffuser discharge pipes originate at the notch of the V. A concrete dam, or weir, runs in the east west direction at the northern end of the Forebay and creates a small, water-filled area called the sealpit. The sealpit maintained a water seal over the circulating water pipes to prevent loss of flow with tidal fluctuations.

Survey Unit 4 consists of the North floor of the Forebay basin, bounded to the south by Survey Unit 5. The survey unit is bounded to the West by Survey Unit 7(at the toe of the Forebay dike's slope) and to the East by Survey Unit 8. Its northern boundary is the concrete weir. Survey Unit 4 consists of rock ledge and sediment media. The Survey Unit has a surface area of approximately 1,410 m 2.B. SURVEY UNIT DESIGN INFORMATION The Forebay received the liquid radioactive discharges from the plant. It was known to have been contaminated to levels in excess of the release limits and extensive remediation activities including underwater dredging, underwater vacuuming, and dry surface vacuuming were performed.

Given the high probability of residual contamination, the Forebay was classified as Class 1.Revision 3 of the Maine Yankee License Termination Plan (LTP) l states that the Forebay dose from residual radioactivity "is so insignificant and the probability so low that an individual would be able to successfully place a viable well within the Forebay, survey measurements of the Forebay surfaces including rip-rap will be limited".

As a result, the survey design for the Forebay is a reasonable approach to demonstrate compliance with the release criteria while not necessarily meeting all of the requirements for a "MARSSIM" survey.LTP, Revision 3 refers to the LTP submitted in October2002 (Reference I) as amended by the MY's addenda of November 2002 (Reference 2). LTP, Revision 3 was approved by the NRC in February 2003 (Reference 3).FR-0400-04, Revision 0 Page 2 of 23 A technical basis document outlining the proposed Forebay survey plan was submitted to the NRC prior to commencing the surveys (Reference 4). The Technical Basis document described and established the technical sufficiency of the underwater in situ and Nal(TI)techniques for use in the Forebay. Attachment 21I of the LTP describes the characterization data obtained from the Forebay. This data formed the basis for the Forebay survey design.The survey unit design parameters are shown in Table 1. This table reflects the current design parameters, some of which have been revised since the survey was completed as discussed in Section H. The survey unit design was not based on sigma and relative shift (per Reference 4). A minimum number of 50 direct samples were planned for the Survey Unit. This number was determined based on the Survey Unit size and was selected to attain a design area factor of 10 per the Forebay Technical Basis Document.

Since the data assessment is unitized, the Sign Test Summary in Attachment 4 uses a value of sigma obtained from volumetric samples from FR 0400 Survey Unit 1. Sample measurement locations wvere determined using a random start point and a square grid. These locations are presented on survey map FR 0400-04a in Attachment

1. The direct measurements consisted of in sit i measurements obtained with the ISOCS detector.The survey unit design also included 170 individual scan grids of 3 m by 3 m (see map FR 0400-4b in Attachment 1). Each grid was scanned using a Nal detector with an alarm setpoint established at background plus 4,000 c/m. This scan survey ensured there were no unidentified areas exceeding approximately 1/2 of the DCGLErc limit. The survey instruments used, their MDC value, and alarm setpoints are provided in Attachment 2.In order to establish the alarm setpoint for the E-600 used for scanning, the underwater background of the Forebay must be known. Due to the varied materials of composition and the bottom topography of the Forebay, background can only be approximated.

As such, two approaches were used to estimate a background for this survey. The first approach consisted of an analytical model based on compiled volumetric sample data from several types of Forebay samples. The next approach consisted of an evaluation of actual Forebay scan data.Based on an evaluation of the results from the two approaches, the generic background value for the Forebay was set at 16,000 cpm. Adding 4,000 cpm to this value provided an alarm setpoint of 20,000 cpm which is equivalent to a scan MDC of approximately 180,000 dpm/100 cm 2.FR-0400-04, Revision 0 Page 3 of 23 TABLE 1 SURVEY UNIT DESIGN PARAMETERS

[ Survey, Unit J Design Criteria l Basis Area 1,41 0 rml Number of Direct 50 Selected based on the design basis of Measurements Required 5 the Forebay Sample Area 28.2 m 1,410 / 50 samples Sample Grid Spacing 5.25 m (28.2)~" Area Factor 10 (conservative)

Design value from the ScanGridSurveyAra__9___

Forebay Technical Basis Document Scan Grid Survey Area 9 mL Background i .-..SSPA-3 (scan) 16,000 cpm DI 6-150 ISOCS (direct) N/A d Provides a scan MDC of Scan Investigation Level Background

+ 4,000 cpm approximately 180,000 dpm/l OOcm See Table 2-2 Source: Forebay Technical Basis Document DCGL" 1.62E6 pCi/mnI Forebay Technical Basis Document DCGLE1C I.62E7 pCi/r 2 Area Factor x DCGL C. SURVEY UNIT RESULTS As required, 50 direct measurements were obtained.

The direct measurement data are presented in Table 2 below. The ISOCS measurements are presented in units of pCi/mi 2.Five direct measurement results were greater than the DCGL, but less than the DCGLENIC.These measurements were evaluated as discussed in Section D.The scan survey was designed for 170 scan grids. Nine grids were deemed inaccessible and could not be scanned due to the proximity of the weir and/or shallow areas along the waterline.

The scan process identified 25 grid locations for investigation.

These grids, plus one additional, were investigated.

The investigated grids are indicated on survey map XR 0400-04b.

The investigation results are discussed in Section D.It should be noted that during early stages of this survey, the alarm setpoint was adjusted daily based on a once-daily background measurement.

The once-daily background was taken at the shoreline which differed greatly in local geometry and/or material composition from the scan geometry/material composition away from the shore. This resulted in an underestimation of background and led to an unacceptable amount of investigations.

Hence, the two step approach was developed to establish the estimated representative background used to evaluate the scan data.2 pCi dpm lpCi cm2 21.62E6 = 36,000 x x 10,000 2"2 100cm 2 2.22dpm 2 FR-0400-04, Revision 0 Page 4 of 23 TABLE 2 DIRECT MEASUREMENTS Cs-137 1 Co-60 1 Unitized Value of Sample Number (pCi/m 2) (pCi/M 2) Unity Rule FR0400041ROO1 O.OOE+00 <6.22E+05 0.384 FR0400041R002 O.OOE+00 <2.55E+04 0.016 FR0400041R003 O.OOE+O0 3.40E+05+11.03%

0.210 FR0400041R004 0.OOE+OO 4.84E+04 + 35.00% 0.030 FR0400041R005 0.OOE+00 <3.65E+05 0.225 FR0400041R006 5.65E+04 + 115.91% 4.19E+05+

9.59% 0.294 FR040004 I R007 O.OOE+00 7.37E+05 + 24.35% 0.455 FR0400041R008 0.OOE+00 <1.I E+04 0.007 FR0400041RO09 0.OOE+00 9.62E+03 + 29.65% 0.006 FR0400041RO10 0.OOE+00 1.62E+05 + 8.85% 0.100 FRO400041ROI I 0.OOE+00 5.40E+05 + 10.36% 0.333 FR0400041R012 4.50E+04 + 94.28% 9.42E+05+

6.50% 0.609 FR0400041R013 1.40E+05 + 56.18% 1.29E+06 + 6.74% 0.885 FR0400041R014 0.OOE+00 5.41E+05+

10.10% 0.334 FR0400041R015 O.OOE+00 2.49E+05+

15.62% 0.153 FR0400041R016 O.OOE+00 3.67E+05+

10.93% 0.227 FR0400041R017 1.22E+05 + 37.66% 3.83E+05 + 8.33% .0.312 FR0400041R018 O.OOE+00 6.77E+05 + 8.13% 0.418 FR040004 IRO 19 O.OOE+00 2.91E+05+13.02%

0.179 FR0400041R020 2.39E+04 + 70.20% 2.23E+05 + 7.46% 0.152 FR040004 I R021 0.OOE+00 1.16E+06 + 7.17% 0.715 FR0400041 R022 4.28E+05 +29.00% 1 .57E+06 + 6.63% 1.231 FR0400041 R023 2.24E+05 +35.89% 1.80E+06 + 6.16% 1.249 FR0400041R024 1.32E+05+

67.19% 5.76E+05+

9.07% 0.437 FR040004 I R025 2.18E+05 + 21.51% 4.72E+05 + 7.02% 0.426 FR0400041R026 7.12E+04+38.95%

3.30E+05+

7.69% 0.248 FR0400041R027 0.OOE+00 4.27E+05+

10.87% 0.263 FR0400041R028 2.97E+05 + 26.00% 5.68E+05 + 8.13% 0.534 FR040004 I R029 2.47E+05 +25.05% 6.88E+05 + 7.28% 0.577 FR0400041R030 1.73E+06 + 45.89% 6.05E+05 +21.56% 1.444 FR0400041R031 7.25E+05+

18.07% 9.86E+04+22.49%

0.508 FR0400041R032 2.88E+05 +30.94% 2.63E+06 +5.96% 1.803 FR0400041R033 0.OOE+00 3.56E+04 + 26.84% 0.022 FR0400041R034 4.87E+04 + 21.61% 1.80E+05 + 6.71 % 0.141 FR0400041R035 5.79E+05 + 74.04% <1.40E+05 0.444 FR0400041R036 6.32E+05 + 16.07% 1.49E+05 + 15.65% 0.482 FR0400041R037 1.17E+05 +27.74% 5.68E+04 +21.48% 0.107 FR0400041R038 2.OOE+05 +60.05% 5.18E+05 +9.54% 0.443 FR0400041R039 1.85E+05 +48.10% 4.33E+05 +9.79% 0.381 FR0400041R040 1.43E+04 + 41.64% 6.68E+04 + 8.56% 0.050 FR0400041R041 3.48E+05+

15.95% 6.23E+04+

18.13% 0.253 FR-0400-04, Revision 0 Page 5 of 23 Cs-137 Co-60 l Unitized Value of Sample Number (pCi/rn 2) (pCi/rn 2) I Unity Rl FR0400041 R042 5.19E+06 + 22.89% 4.78E+05 + 27.43% 3.501 FR0400041R043 1.76E+05 + 26.92% 5.98E+04 + 24.22% 0.145 FR0400041R044 2.91E+05+19.25%

4.60E+05 + 7.53% 0.463 FR0400041R045 1.68E+05 + 36.59% 8.47E+04 + 21.46% 0.156 FR040004IR046 0.OOE+00 < 7.13E+04 0.044 FR0400041 R047 9.84E+04 + 44.95% 3.01E+04 + 27.21% 0.079 FR0400041 R048 1.83E+05 +40.75% 4.11E+05+8.23%

0.367 FR0400041R049 1.38E+05 + 52.77% 5.43E+05 + 8.50% 0.421 FR040004 I R050 0.OE+00 8.28E+05 + 7.21% 0.511 Mean N/A N/A 4.56E-01 Median N/A N/A 3.33E-01 Standard Deviation N/A N/A 5.75E-01 Range N/A N/A 5.94E-03 -3.50E+0"<" indicates MDA value for non-dectect Co-60 result D. SURVEY UNIT INVESTIGATIONS PERFORMED AND RESULTS The scan process identified 25 grid locations for investi ation. These grids, plus one additional, were evaluated using investigation package XR 0400-04. All investigations consisted of in situ measurements with the ISOCS detector.

The investigation results were combined with the five direct measurement results which exceeded the D CGL for comparison with the DCGLEMC criteria.

The aggregate results wvere determined to be in compliance with the Elevated Measurement Comparison limit. This assessment is included as Attachment 3 (Table 3-1).E. SURVEY UNIT DATA ASSESSMENT An analysis of the direct measurement results, including the mean, median, stand~ard deviation, and sample result range, are provided in Table 2. Positively detected values are bolded in the table. Since Cobal t-60 is the primary radionuclide of concern, non-detect values wvere assumed present at the MDA. Non-detected values for Cesium-137 wvere assumed not to be present. However, some Cs-137 values were reported positive with high uncertainties that were less than the post-priori MDA. These have been included in Table 2 and 3-1 as positive results. The column to the right is the DCGL unity column. Five values exceeded the DCGL. The five values were evaluated using the EMC criteria (Table 3-1) and found to be acceptable.

The mean value of this column indicates that the direct sample's were at 45.6% of the DCGL limit. This is equivalent to an annual dose rate of 8.5E-3 mrem .The maximum direct sample result was equivalent to 35% of the design DCGLENC. The sample standard deviation is larger than the design sigma, however, no additional measurements were required due to the results of the Sign Test..Twenty-five SSPA-3 scan alarms were encountered while surveying.

Since the scan grids were 3m x 3m squares, an Area Factor of 35 was used. This area factor was also conservatively applied to direct measurements since the area extent for the ISOCS in sitz gamma spectroscopy measurement geometries is approximately 8 m>.The 25 verified scan alarms, along with one additional grid and the five direct measurements that were above the DCGL, were investigated as shown in Table 3-1 of Attachment 3, and determined to be approximately 58.5% of the DCGLENIC.This number is calculated by multiplying the mean value for direct measurements (0.456 of the DCGL) by 1 .87E-2 mrem/y, the highest dose scenario outcome for the Forebay area.FR-0400-04, Revision 0 Page 6 of 23 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 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 %vell as a listing of the key release criteria.

As shown in the Table, several attributes required further evaluation.

As discussed in Section E, the subject release criteria have been satisfied.

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 I survey unit. Five of the direct measurements exceeded the DCGL but were less than the DCGLE?,c.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 with variance consistent with expectations for a Class I survey unit.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 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 Due to remediation activities which removed Co-60 contaminated sediment, the source term appears to have an increased Cs-137 to Co-60 ratio. This was addressed by separately including the Cs-I 37 results (positive detects) in the data evaluation.

As stated in the LTP, the Forebay survey was anticipated to be a "limited" survey with"limited" never defined. The intent was to demonstrate adequate remediation of the Forebay source term using the new survey techniques described in the Technical Basis Document.Because Co-60 was the predominant nuclide in terms of both abundance and dose contribution, the measurements focused on detection of Co-60 activity.

Some instances of high Cs-137 activity were found in FR-0400 SU 4 and SU 5 which challenged the EMC unity calculation.

Had these high Cs-137 values been anticipated, the investigation criterion could have been adjusted to better account for them.FR-0400-04, Revision 0 Page 7 of 23

11. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit 4 was designed and performed using the criteria of the approved Forebay Technical Basis Document (Reference

4) and LTP (Revision 3 Addenda).

In order to deal with the initial failure to meet thq EMC unity criteria, a change to the DCGL for the Forebay floor from 18,000 dpm/I 00 cm to 36,000 dpm/I 00 cm was processed under 1 OCFR50.59 as allowed by the LTP. The dose remained within the 10 mrem/y and 4 mrem/y drinking pathway limits as shown above. The annual dose from the Forebay floor, with contamination levels at the new DCGL, remains very low with a value of 1.87E-02 mrem/y.No other LTP changes have been made that would affect the survey results or conclusions for this survey unit.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. Five direct measurements exceeded the DCGL, while the survey unit mean was less than the DCGL. The Sign Test and Elevated Measurement Comparison test were performed and found satisfactory as discussed below.A Sign Test Summary analysis demonstrated that the Sign Test criteria were satisfied.

The sample standard deviation is larger than the design sigma. However, no additional measurements were required because the number of samples was increased during initial survey design to achieve a higher area factor, and the survey unit passed the Sign Test.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 I survey unit.The scan survey design for this survey unit was developed in accordance with the Forebay Technical Basis Document with significant aspects of the design discussed in Section B and Table 1. Scanning resulted in a number of verified alarms (Section C) for evaluation.

Attachment 3 provides the areas identified by verified alarms and provides the results of the investigation actions. The areas under investigation were evaluated using the appropriate area factor. The survey unit was determined to satisfy the elevated measurement comparison unity rule per LTP methodology (approximately 58.5% of the DCGLEMC criteria limit.).It is concluded that FRO400 Survey Unit 4 meets the release criteria of I OCFR20.1402 and the State of Maine enhanced criteria.J. REFERENCES

1. Maine Yankee License Termination Plan, Revision 3, October 15, 2002 2. Maine Yankee letter to the NRC, MN-02-061, dated November 26, 2002 3. NRC letter to Maine Yankee, dated February 28, 2003 4. Maine Yankee letter to the NRC, MN-03-51, "Forebay Technical Basis Document," dated September 3, 2003 5. Maine Yankee Calculation EC-041-01 6. Maine Yankee Calculation EC-003-04 FR-0400-04, Revision 0 Page 8 of 23 Attachment I Survey Unit Maps FR-0400-04, Revision 0 Page 9 of 23 Maine Yankee I Map ID #: FR 0400 SITE Decommissioning Team Maine Yankee Decommissioning Project Survey Form Revised: 12-17-04 Survey Type: [ Remediation 0 Turnover U Final Status Survey Survey Area Name: Forebay Site Map 623,000 E 623,500 E 624,000 E 624,500 E 625.000 E o a.A 8 Q 9A z z z z z z SCALE 0 400 800 1200 Note: Grid based on Maine State Coordinate System (West Zone) NAD 1927 MN E N FR-0400-04, Revision 0 Page IO of 23 Maine Yankee Map ID #: FR 0400-4a Decommissioning Team I Mainte I'ankee Decomniissionitig Project Survey3 Forni I Revised. 11-04-03 Survey Type: 0 Characterization O Turnover I Final Status Survey I Survey Area Name: Forebay Floor FR 0400: FOREBAY Survey Unit 4, North End Forebay Floor Direct Points R001 -R050 sfh( e 5'IV_I'r/EBAY I I I.- /D.WO I I*R050, ., 90j5 : 'R9 R.27 R016.nnA ._R03 R028 eRO4l0 -R2 , ~ 1..... W03 7

• 04 -, -RO1 2)48 O3, ' bfO1 7 R F0239 -~1 R03 , -- 0 82't- "03 ---I02 ,. 'M 8'I ..-R004/)47 GRAPHIC SCAJL 9 .1,P .2O 3,0, 4,0, S6)LEGEND v*Rip-Rap Extents (Forebay Bottom)Concrete...............

Ledge 525m (L) Square Grid eF01 6 Direct Point Location N y X FR-0400-04, Revision 0 Page I I of 23 L = 5.25, N =50 SA = 1410 sq-rn Scale :1"=30' Maine Yankee Map ID #: FR 0400-b Decommissioning Team Afainc Yankee Decommissioning Project Survey Form M Revised: 11-1003 Survey Type: 0 Characterization O Turnover 0 Final Status Survey Survey Area Name: Forebay Floor FR 0400: FOREBAY Survey Unit 4, North End Forebay Floor Survey Scans R051 -R220 R210 ,R146 R122 R211 RI90' R1 R145., R12 R1 00/2*2 R208 R189 R169 R 16R R123 r7120 RI0t -P078 -060/R2077 R44 8 R8005 /P23 R207 R.'1 70 R148., .P124,

• R102 R085 R20R'18 70 6 R4 19R097 R077a,/1303 *.R081 P6 BAY R24 P19 R11664 ~ 15 E P05 R86R16 P4 2 /R125 ---. R 0963 R076/ R058.215k ,R17 R 18 P 'P062... .R214 P1..8. 5 16 5 R141 /R1 -095' R. L082g N .R-_ Y _R20 5_ R 3mSqu R12 6 R I4 , FR-0400-04 R v i n R 0R7 6R150 S e a6 P g 1R09 5 RO

• 0 P056 P 217 RP19 4! /R174 1-/R5. !P!14 R106704 .'R064 .P "202 R 185i R127P39'~-R11 0593 aR0565 .P28P9 R7 .. R15 1 .' / 19 'R 17 057406-P0 12 .../RP173 / -. R18/OP14 ~ P 92 ' P02 f.P5 200 PR18 P13 ..4 1 P168 RP8 066 4 R1638 P176 PR134 P09/R178 /R174P110 R0P093O5Z 17/RI39/.

/ /R 0 1 C /R16257'R8 Lel4d/e -N4 173mSqae ndF-0000, evs on90 980 It~an um e Page 1373 -e l,-II- * -%-Jm- I-& lwzP4-111

%11-0110 .I -.1w Maine Yan~e aieYnkee eomsinn rjc uvyF i Map ID #: XR 0400-04b Decommissioning Team Alne Yankee Decommissioning Project Stiri'ey ForIii Revised: 11-24-03 Survey Type: = Characterization 1U Turnover X Final Status Survey Survey Ar6a Name: Forebay Floor XR 0400: FOREBAY Survey Unit 4, North End Forebay Floor Investigation Grids cS0,4e 16 r-= Investigation Grids fK = Inaccessible Grids LEGEND to GRAPHIC SCAJLE- Rip-Rap Extents (Forebay Bottom) 9 p 1 0 0 40 S0ft)Concrete...............

I. Ledge 3m Square Grid FR-0400-04, Revision 0 R150 Survey Scan Number Page 13 of 23 Y i SA= 1410 sq-m Scale: 1 "=30' Attachment 2 Survey Unit Instrumentation FR-0400-04, Revision 0 Page 14 of 23 TABLE 2-1 INSTRUMENT INFORMATION SCAN INSTRUMENTATION 1929 l 726557 (SSPA-3) 180,000 dpm/100 cm'1928 2056 (SSPA-3) 180,000 dpm/100 cm'2619 2253 (SSPA-3) 180,000 dpm/100 em'ISOCS DETECTORS (in siftl measurements)

ISOCS Detector I MDC (pCi/mn')7607 1 See Table 2-2 TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, INVESTIGATION LEVEL, AND DESIGN DCGLENMC Detector SSPA-3 J ISOCS Scan MIDC -180,000 dpm/100 cm 2 5.0E5 pCi/m'Co-60 nominal 36,000 dpm/100 cm' 36,000 dpm/100 cm'DCGL Co-60, Cs-137 Co-60, Cs-1 37 Investigation Level 20,000 cpm (Alarm Setpoint) (Background

+ 4,000 cpm) N 360,000 dpm/100 cm' 360,000 dpm/100 cm'Design DCGLEMe 1 .62E7 pCi/M 2 1.62E7 pCi/M 2 FR-0400-04, Revision 0 Page 15 of 23 Attachment 3 Investigation Table FR-0400-04, Revision 0 Page 16 of 23 TABLE 3-1 INVESTIGATION RESULT TABLE Co-60 Cs-137 Cbl eim DGEI Grid Co-60 Cs-137 Minus Minus Csbalt I'Cesium DCGLI Grd(pCi/rn

2) (pCi/rn) SU Mean SU Mean Activity Activity Comparison

__ __ _ __ _ __ _ __ __ _ __ _ __ __ __ _ __ _ __ _ (pCi/rn 2) (pCi/rn 2) (Unitized) (Unitized)

FractionI 60 6.41E+04 + 26.88% 0.OOE+00-N/A N/A N/A N/A < DCGL 61 5.25E+05 + 16.12% O.OOE+00 N/A N/A N/A N/A < DCGL 62 7.47E+04 +/- 17.67% 0.OOE+00 N/A N/A N/A N/A < DCGL 63 <1.85E+06 O.OOE+00 <1.48E+06 N/A 0.0261 N/A 0.026 64 3.64E+05 +20.79% O.OOE+00 N/A N/A N/A N/A < DCGL 65 4.37E+05 +/-22.72% 0.00E+00 N/A N/A N/A N/A <DCGL 66 < 8.05E+05 0.OOE+00 N/A N/A N/A N/A <DCGL 77 2.54E+05 11.13% 0.OOE+00 N/A N/A N/A N/A < DCGL 78 1.20E+O5 +/- 14.86% 0.OOE+00 N/A N/A N/A N/A < DCGL 91 4.02E+05 + 19.28% 0.OOE+00 N/A N/A N/A N/A < DCGL 92 <1.42E+06 0.OOE+00 N/A N/A N/A N/A <DCGL 99 3.57E+05 + 8.92% 0.00E+00 N/A N/A N/A N/A < DCGL 100 <1.55E+06 O.OOE+00 N/A N/A N/A N/A <DCGL 101 4.41E+05 + 18.19% 0.OOE+00 N/A N/A N/A N/A < DCGL 106 1.OOE+06 + 17.25% 0.00E+00 N/A N/A N/A N/A <DCGL 108 1.14E+06 + 11.13% O.OOE+00 N/A N/A N/A N/A < DCGL 109 4.15E+05 + 18.76% O0.OOE+00 N/A N/A N/A N/A < DCGL FR-0400-04, Revision 0 Page 17 of23 ICo-60 Cs-137 Cobalt Cesium DCGLENIc Gr.dCo-60 I Cs-137 Minus Minus A Grid (pCi/m 2) (pCi/m 2) SU Mean SU Mean Activity Activity Comparison

_ ____(pCi/m________

_(Uniti/ed) (pCi/)Unitize)

Fraction 122 < 1.06E+06 O.OOE+O0 N/A N/A N/A N/A < DCGL 123 9.03E+05 + 12.64% 0.00E+00 N/A N/A N/A N/A < DCGL 133 4.65E+05 _ 7.76% 4.80E+04 + 45.05% N/A N/A N/A N/A < DCGL 134 3.68E+05 + 8.71% 0.OOE+00 N/A N/A N/A N/A < DCGL 135 1.14E+05 + 13.39% 5.43E+04 + 37.10% N/A N/A N/A N/A < DCGL 146 < 2.49E+06 O.OOE+O0 < 2.12li+06 N/A 0.0374 N/A 0.037 169 7.09E+05 + 15.48% 0.OOE+00 N/A N/A N/A N/A < DCGL 179 2.98E+05 O.OOE+00 N/A N/A N/A N/A < DCGL 220 < 8.I1 E+05 0.OOE+00 N/A N/A N/A N/A < DCGL FR0400041 R022 1.57E+06 f 6.63% 4.28E+05 + 29.00% 1.20E+06 3.11 E+05 0.021 0.005 0.027 FR0400041 R023 1.80E+06 _ 6.16% 2.24E+05 _ 35.89% 1.43E+06 1.07E+05 0.025 0.002 0.027 FR0400041R030 6.05E+05 + 21.56% 1.73E+06_

45.89% 2.34E+06 1.62E+06 0.004 0.029 0.033 FR0400041 R032 2.63E+06 +/- 5.96% 2.88E+05 + 30.94% 2.26E+06 1.71 E+05 0.040 0.003 0.043 FR0400041 R042 4.78E+05 + 27.43% 5.19E+06 + 22.89% 1.07E+05 5.08E+06 0.002 0.090 0.091 SU Mean 0.301 E4evated 0°284 0.284 Areas 0.585_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ T o ta l _ _ _ _ _ _NOTES 1. "<" indicates MDA value for non-detect Co-60 results.2. Non-detect Cs-137 results shown as 0.OOE+00 as discussed in Section E.3. The Co-60 and Cs- 137 mean values were calculated using Table 2 values except that the values for the five directs shown in Table 3-1 were excluded.4. A conservative area factor (AF) of 35 was used based on a scan grid area of 9 m 2.5. The unitized elevated activity was calculated as follows: (Investigation Result -SU Mean) / (AF)DCGL FR-0400-04, Revision 0 Page 18 of 23 Attachment 4 Statistical Data FR-0400-04, Revision 0 Page 19 of 23 Survey Package FRO400 Unit 4 Soil Sign Test Summary~A. u-, <., o~ .3'Evalauatonlntputvaiue rs-;, l .................

<K i gT -'d "Cmmnts '~4 sge Survey Package: FRO400 Forebay Survey Unit: 04 Evaluator:

DR DCGL,: 1.002+00 DCGLemc: 1.OOE+01 LBGR: 5.OOE-01 Sigma: 2.58E-02 (0.31 pCi/g I 12 pCi/g)Type I error: 0.05 Type II error: 0.05 Nuclide: UNITY Soil Type: N/A Z.<: 1.645'Za0: 1.645 Sign p: 0.99865 Calculated Relative Shift: 19.3 Relative Shift Used: 3.0 Uses 3.0 if Relative Shift is >3 N-Value: 11 N-Value+20%:

14 Sampe Data.Va usi2 3<,-Number of Samples: 50 Median: 3.33E-01 Mean: 4.56E-01 Net Sample Standard Deviation:

5.75E-01 Total Standard Deviation:

5.75E-01 SRSS Maximum: 3.50E+00 Adjusted N Value: 50 S+ Value: 45 Critical Value: 31 Sign test results: Pass Sufficient samples collected:

Pass Maximum value <DCGL,: Investigate See Sections D&E of Release Record Median value <DCGL,: Pass Mean value <DCGL,: Pass Maximum value <DCGLemc:

Pass Total Standard Deviation

<=Sigma: Investigate See Section F of Release Record Criteria comparison results: .,Investigate See Section I of Release Record The sur unit passes j-talcoiaust-iona Ie- Th-eSUpa-ss_____es

_ _____The survey unit passes all conditions:l Investigate The SU passes FRO400-SU4-SoilSign 12119/04 12:03 PM FR-0400-04, Revision 0 Page 20 of 23 FR-0400 SU-4 Quantile Plot 4 3.5-TI 0 4, w 0 CD0'..J g~.O 0" vb t.j W (A 5'40 0 N a-C.)._--SE 3 2.5 2 1.5 1-.4--- .- .4 I i i i! I I:1 t.il f* Activity (Unitized)-Median (Unitized)

I.... -.. _ .- ... ...... .0.5 0 l 0 25 50 75 100 Percent Page/Date/Time Database Variable One-Sample T-Test Report 2 12/21/04 7:24:47 AM C:\Program Files\NCSS97\FR0400SU-4.S0 C2 Plots Section Histogram of FR-0400, SU-4 50, u, 0, 0)C.E CD 0 E I 38 25 13-0 .00o0' 1 .0o0* 2.000 Activity (unitized 00 0 , 4.00l FR-0400-04, Revision 0 Page 22 of 23 One-Sample T-Test Power Analysis Page/Date/Time 2 12/21/04 7:26:33 AM Chart Section a)0~1.0- 0 0.8-0.6-0.4-0.2-0.0 0.4 Retrospective Power Curve...- -.... ...._ .I. I 0.6 0.8 1.0 Survey Unit Mean (unitized) 1.2 FR-0400-04, Revision 0 Page 23 of 23