ML043640272

Maine Yankee Final Status Survey Release Record FR-0400 Forebay Survey Unit 1

ML043640272
Person / Time
Site:	Maine Yankee
Issue date:	12/22/2004
From:	Pillsbury G, Randall D B Maine Yankee Atomic Power Co
To:	NRC/FSME
References
MN-04-060, RA-04-118 FR-0400-01, Rev 0
Download: ML043640272 (24)

Text

MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0400 FOREBAY SURVEY UNIT 1 Prepared By: t I/c Date: // -/0 -FSS Engineer -Signature FSSi pe t. *,gat/ u Reviewed By: -IV, Z-1e Date: /n}pFSSendent Re e Signature Printed Nanme Reviewed B y: Date:// C, deendent Re 'ew- Signature Approved By: X___ ___ ___Date: ///"3 ccritendt,+7 Signature/Printed Name 7 Approved By: Ah a MDate: /t/2 FSS, MOP -Signature-4.0' t- L:<w Printed Name Revision 0 MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0400 FOREBAY SURVEY UNIT I A. SURVEY UNIT DESCRIPTION Survey Unit I is located within Survey Area FR-0400, the Forebay. The Forebay is located south of the radiologically Restricted Area of the site at coordinates 407,250 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.

Twvo 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 forn 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 I consists of the floor of the sealpit and its sloping walls up to an elevation of 4.5 feet. The sealpit consists of a rock and gravel floor, previously covered with sediment', and exposed ledge walls on the east and xvest sides. The weir forms the south end and the concrete support structure of the circ water pipes forms the north end. The Survey Unit has a surface area of approximately 640 m 2.B. SURVEY UNIT DESIGN INFORMATION The Forebay received the liquid radioactive discharges from the plant. It wvas 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 wvere 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)2 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.A large amount of the sediment was removed during remediation; some sediment remained which was ued for volumetritcsampling.

2 LTP, Revision 3 refers to the LTP submitted in October 2002 (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-0400-01, Revision 0 Page 2 of 24 A technical basis document outlining the proposed Forebay survey plan was submitted to the NRC prior to commencing the surveys. One aspect of the Technical Basis document was to describe the use of underwater in situ gamma spectroscopy for performing some of the Forebay survey measurements.

The sealpit was chosen as one of the test areas to demonstrate the use of in situ surveys. As a result, many measurements were made, both in situ and volumetric, of the residual activity in the sealpit. The in situ measurements were used as characterization data for the survey unit; the volumetric measurements were used for the survey unit direct measurements.

The survey unit design parameters are shown in Table 1. Given a relative shift of 3.0, it was determined that 14 direct measurements were required for the Sign Test. Each sample measurement location was determined using a random start point and a square grid. These locations are presented on survey map FRO400-03 (Attachment.

1). All direct measurements consisted of soil samples obtained at the required locations.

The samples are analyzed with laboratory gamma spectroscopy.

The survey unit design also included 179 individual scan grids of approximately 2 m by 2 m (see map FRO400-04, Attachment 1). Each grid was scanned by Nal detector.

The survey instruments used, their MDC values, and alarm setpoints are provided in Attachment

2. The design DCGLEMC is greater than the scan MDC. The investigation level was established at approximately DCGLEMc plus background.

Background values were established for the scan measurements, based on local scaler values in the survey unit. These background values were used to establish scan alarm setpoints, and to confirm the scan MDCs used were appropriate.

Due to the different media that exists in the survey unit, a wide range of backgrounds was encountered.

The scan grids were arranged into five background groups based on similar readings.

A different alarm setpoint was developed for each group.FR-0400-01, Revision 0 Page 3 of 24 TABLE I SURVEY UNIT DESIGN PARAMETERS Survey Unit Design Criteria Basis Area 640 ml Based on an LBGR of 3.5 pCi/g, Number of Direct sigma 3 of 0.31 pCi/g, and a relative Measurements Required 14 shift (adjusted) of 3.0.Type I = Type 1I 0.05 Sample Area 45.7 mZ 640 m} / 14 samples Sample Grid Spacing 6.76 m (45.7)" Area Factor 1.5 LTP, Table 6-12 Scan Survey Area 640 ml Class I -100%Background I-2 'SPA-3 (scan) Varied DI 6-150, EC-009-01,______________14,570 to 22,650 LTP Section 5 Scan Investigation Level 20 pCi/g + background S DCGLE2tC____ ___ ____ ___ ___ ___ ___ ___ ____ ___ ___ See Table 2-2 (Attachm ent 2)DCGI. 7.0 pCi/g Co-60 Forebay Technical Basis Document Design DCGLENIc 10.5 pCi/g Co-60 Area Factor x DCGL____ ___ ____ ___ ___ _ __ ___ ____ ___ ___ (from Table 6-12 of the LTP)C. SURVEY RESULTS Fourteen direct measurements were required, sixteen were actually taken. The direct measurement data are presented in Table 2. All direct measurements were below the DCGL.Sample S001 also had detectable Sb-125 (not shown on Table 2) at less than 0.5% of the DCGL.All accessible areas were scan surveyed.

Portions of the survey unit could not be surveyed due to interferences, safety hazards, and/or water. Fifty-four grids within the survey unit were identified as needing investigation due to high background and/or verified alarm. The investigations are discussed in Section D.3 3 Sigma was determined using post remediation survey data.4 This DCGL was used for the survey design. The actual DCGLs listed in Table 2-2 were used for data evaluation.

Refer to Section 1- for additional discussion.

FR-0400-01, Revision 0 Page 4 of 24 TABLE 2 DIRECT MEASUREMENTS Samplc Number l Cs-137 (pCilg) l Co-60 (pCilg) l Unitized Values I I__________

I of Unity Rule FR0400-1-SSOOI 1.02E+00 + 6.98E-02 4.95E+00 + 1.96E-01 4.41E-01 FRO400-1-RS002 3.22E-02 + 1.33E-02 1.50E-01 + 1.59E-02 1.34E-02 FRO400-1-RS003

<2.9613-02 6.03E-02 + 1.36E-02 5.88E-03 FRO400-1-RS004

<3.59E-02

<3.8213-02 4.21 E-03 FRO400-1-SS005 1.88E+00 + 1.33E-01 7.76E-01 + 4.52E-02 1.19E-0I FRO400-1-RS006

<3.63 E-02 <3.79E-02 4.20E-03 FRO400-1-RS007

<3.83E-02 5.74E-02 + 1.71E-02 5.88E-03 FRO400-1-RS008

<3.73E-02

<4.29E-02 4.65E-03 FRO400-1-SSOO9 3.06E-01 + 3.21E-02 1.45E-01 + 1.79E-02 2.09E-02 FRO400-1-SSO10 3.30E-01 + 3.80E-02 6.2 1E-01 + 3.96E-02 6.1213-02 FRO400-1-SSO I1 5.30E-01 + 4.45E-02 1.06E+00 + 5.26E-02 1.04E-01 FRO400-1-SS012 6.31E-01 + 5.61E-02 5.85E-01 +3.92E-02 6.69E-02 FRO400-1-RS013

<3.57E-02

<4.23E-02 4.55E-03 FRO400-1-RSO14 1.82E-02 +7.37E-03 7.96E-02 + 1.64E-02 7.1513-03 FRO400-1-RS015

<2.95E-02 5.33E-02 + 1.63E-02 5.28E-03 FRO400-1-RS016

<2.77E-02

<2.62E-02 2.98E-03 Mean 3;14E-01 5.45E-01 5.44E-02 Med ian 3.68E-02 7.OOE-02 6.51 E-03 Standard Deviation 5.09E-01 1.22E+0O 1.1OE-01 Range 1.82E-02 -1.88+EOO 2.62E-2 -4.95E+00 2.98E-03 -4.41E-O1"<" indicates MDA value.D. SURVEY UNIT INVESTIGATIONS PERFORMED AND RESULTS The scan process identified 54 grid locations of potentially elevated activity.

These were investigated by survey investigation package XR0400-01.

Investigated grids were divided into four I m 2 x I m 2 grids, rescanned, and a sample collected from each I m grid at the highest scan location.

Eight of the 54 investigated grids had fewer than the typical 4 investigation samples due to grid geometry, interferences, safety hazards, etc. These investigation results were evaluated against the DCGLEMC criteria and determined to be in compliance.

This assessment is included as Attachment 3, Table 3-1. Investigation data is presented in Table 3-1 as the average of the multiple samples from the investigated grids.FR-0400-0l, Revision 0 Page 5 of 24 E. SURVEY UNIT DATA ASSESSMENT An analysis of the direct sample measurement results, including the mean, median, standard deviation, and sample result range, are provided in Table 2. All sample measurement results were less than the DCGL. Positively detected values are bolded in Table 2. The mean value of the DCGL unity column in Table 2 indicates that the direct samples were at 5.44% of the DCGL limit. This is equivalent to an annual dose rate of 0.49 mrem/y 5.The maximum direct sample result was equivalent to 44% of the DCGL. The sample standard deviation is larger than the design sigma, however, no additional measurements were required (the survey had sufficient power -refer to Section F).Fifty-four areas were identified for investigation while surveying and were investigated as shown in Table 3-1 of Attachment

3. The potential elevated area size was limited to a 2m x 2m grid with an Area Factor of more than 4.1. One of the 54 verified alarms was determined to be greater than the DCGL. When this is added to the SU mean, the result equals 36.7% of the Elevated Measurement Comparison unity limit, thereby satisfying the EMC criterion.

F. ADDITIONAL DATA EVALUATION Attachment 4 provides additional data evaluation associated with this Survey Unit, including relevant statistical informnation.

Based on survey unit direct measurement data, this attachment provides the Sign Test Summary, Quantile Plot, Histogram, and Retrospective Power Curve..1. 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 unitized 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, except for the final sigma, were clearly satisfied for the FSS of this survey unit. Based on the results of the Sign Test and the magnitude of the final sigma, it is evident that the increase did not adversely affect the survey design and a sufficient number of samples were obtained.2. The Quantile Plot was generated from unitized direct measurement data listed in Table 2.The data set and plot are consistent with expectations for a Class 1 survey unit. All of the measurements are below the DCGL of 12.01 pCi/g Co-60 and 34.76 pCi/g Cs-137.3. A Histogram Plot was also developed based on the unitized direct measurement values.This plot shows that the direct data were essentially 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.5 This annual dose equivalent is based on the Forebay technical basis document (Reference 4), which shows that the excavation scenario DCGL is equivalent to 9 mrem/y.FR-0400-01, Revision 0 Page 6 of 24 G. CHANGES IN INITIAL SURVEY UNIT ASSUMPTIONS ON THE EXTENT OF RESIDUAL ACTIVITY Due to remediation activities, the source term appears to have increased Cs-137 to Co-60 ratios. This was addressed by separately evaluating Cs-1 37 and performing data analysis on unitized values.The distribution of contaminant activity was not uniform across the survey unit.Contamination tended to be in the highest concentrations in small pockets of a few square inches between boulders or in recesses along the ledge. Since these small pockets were the only locations with soil media available for sampling, the results likely overstate the extent of remaining activity, as the media volume is very small.H. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit I was designed and performed using the criteria of the approved Forebay Technical Basis Document (Reference

5) and LTP Revision 3 Addenda (Reference 1 and 2). Subsequent LTP changes have been evaluated and have no impact on the design, conduct, or assessment of the final status survey of Survey Unit 1.However, a change was made to the soil excavation scenario (due to the challenge to the EMC criteria in SU 7 and SU 8) which increased the Forebay soil DCGL from a value equal to the RA soil dose limit to one which incorporated the entire 10 (9 actually used) mrem/y-limit allowed for soil outside the RA. This change raised the DCGLs for Co-60; C:s-I 37, and Sb-125 to 12.01 pCi/g, 34.76 pCi/g, and 69.52 pCi/g respectively.

The surface soil area factois were applied to these values to derive the appropriate DCGLEMC values which were also applied to SU-1.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 12.01 pCi/g Co-60 and 34.76 pCi/g Cs-l 37.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 due to power of sign test.FR-0400-01, Revision 0 Page 7 of 24 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 LTP with significant aspects of the design discussed in Section B and Table 1. Scanning resulted in a number of verified alarms (Section C) and grids with high background for evaluation.

Attachment 3 shows the areas identified for investigation 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 at 37% of the DCGLEMC criteria limit.It is concluded that FR-0400 Survey Unit I 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 Calculation EC-041-01, Revision I 5. Maine Yankee letter to the NRC, MN-03-051, Forebay Technical Basis Document, dated September 3, 2003 FR-0400-01, Revision 0 Page 8 of 24 Attachment I Survey Unit Maps FR-0400-01, Revision 0 Page 9 of 24 D Maine YianKeeam Alaine Yankee Deconinnssioning Project Sun'ey ForM Map ID #: FR 0400-SITE Decommissioning Team I Survey Type: [. Remediation

[-I Turnover U Final Status Survey Survey Area Name: Forebay Seal Pit Site Map SURVEY AREA, FR 0400-01l______ _ FO) 31RD -623,000E FOXBIRD ISLAND 624.500 E 625,000 E o o o o 0 o (3' 0 C' b. .S 8 o 0 0 a 0 0 z z z z z z MN 4--- EzD N Note: Grid based on Maine State Coordinate System (West Zone) NAD 1927 FR-0400-01, Revision 0 Page 10 of 24 Maine Yankee Decommssionig Team Maine Yankee Decommissioning Project Survey Form Map ID #: FR 0400 REF Decommissioning Team Ma ID#FR00RE Survey Type: El Investigation 0 Turnover 1 Final Status Survey I Survey Area Name: FRO400 -FOREBAY SEAL PIT Seal Pit FSS Survey Unit Reference

1. 1 -3 Maine Yankee Decommissioning Team Ainaeojecms Proe y Form IMap ID #: FRO400-03 Survey Type: O Characterization 0 Turnover

• Final Status Survey I Survey Area Name: FOREBAY SEAL PIT FR 0400: FOREBAY, SEAL PIT Survey Unit I -SOIL/SEDIMENT SAMPLE LOCATIONS

1. S001 -S016 Surface Area is approximately 640 sq-m-A=- --\S\0L\S41\LkLEIOCATKI N\\\ \A\RandomStart -x321 \1\.14 /FOREBAY g 31.2.1066) \\ \\\\\\g01.)10.66) 0,0 i b 00--39)(21.58, 1Bu)-~FR-0400-01, Revision 0 GAHCSAE Page 12 of 24 0

• 0 20 30 ,4*0 SMIt Maine Yankee mAMaine Yankee Decommissioning Project Survey For,,: Map ID #: FRO400-04 Decommissioning Team I Survey Type: 0 Characterization O Turnover U Final Status Survey Survey Area Name: ForeBay Seal Pit FR 0400: FOREBAY, SEAL PIT Survey Unit 1, Sediment Area Gamma Scans Grids # S046 -S224 Surface Area is approximately 640 sq-m N, X\KK\\\ \>2v@\/W\\\\\U

\\ Vo\N S// /S059 \S052\ \\ \\\/ S0745 S06\S076 /073 S061 Grid = approx. 2m X 2m S077 S072S062//100 / /08 / 071 /S070 t \\X \S 1 S098 S080 56 5@/127 S10C096 S08 67 8126/ S104 095 S0083S06 S128 /S125 S105 0943 S084---- 0 S1 1207 S2, S191/\ S178 /\S093 /\S16 S\\\\\\\\/ S2155 S13 S176 S1l9o g\\S4/13 S121S175 S170 \4 ,(S185/ 160 / \ 153/\ 14\s1 S1/ S4\\\\\ z 187 S'llli/ >/S1o/\/188/\/181

/ 164//19,/

1 8'/ 1 5llllll\//S209S89

\S S165 \/148 t/139//14l\llll 1- / S21 \S20/ 4S190 \ 17 S171-21 S201 S 819= -/7/ S23S- S1 2r4r&-/ /-,-- ,----------\S1 4\/ 1 5// 17 y 14 ( mS1/ S23S9S7 /\/11>/ r /FR-0400-01, Revision 0/~ /// ,_ _ =Page 13 of 24 Attachment 2 Survey Unit Instrumentation FR-0400-01, Revision 0 Page 14 of 24 TABLE 2-1 INSTRUMENT INFORMATION E-60U S/N J Probe SIN (type)2489 2055 (SSPA-3)2491 725328 (SSPA-3)2490 726560 (SSPA-3)2488 725332 (SSPA-3 2490 725332 (SSPA-3)2617 726560 (SSPA-3)2491 725328 (SSPA-3)2490 2055 (SSPA-3)2488 725328 (SSPA-3)1622 725332 (SSPA-3)1929 726560 (SSPA-3)HPGe Detectors for Lab Analysis of Volumetric Sample Detector Number MDC (pCi/g)I (nominal)0.15 Co-60 FSS-1 0.15 Cs-137 0.1 Sb-125 0.15 Co-60 FSS-2 0.15 Cs-137 0.1 Sb-125 0.15 Co-60 DET-2 0.15 Cs-137 0.1 Sb-125 0.15 Co-60 DET-3 0.15 Cs-137 0.1 Sb-125 TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, INVESTIGATION LEVEL, AND DESIGN DCGLEM1C Detector SSPA-3 Scan MDC 5.9 pCi/g____ ___ ___ ____ ___ ___ (N ote 1)12.01 pCi/g Co-60 DCGL 69.52 pCi/g Sb-125_34.76 pCi/g Cs-137 Investigation Level 9500 c/rn + background Alarm Setpoint (20 pCi/g + background) 18 pCi/g Co-60 Design DCGLElIC 104.28 pCi/g Sb-125 52.14 pCi/g Cs- 1 37 Note 1: Design Scan M /DC, LTP 1 able 5-6 FR-0400-01, Revision 0 Page 15 of 24 Attachment 3 Investigation Table FR-0400-01, Revision 0 Page 16 of 24 TABLE 3-1 INVESTIGATION TABLE FSS SURVEY RESULTS _ INVESTIGATION RESULTS Alarm Scan Area Co-60 Sb-125 Cs-137 DCGLENtC Grid Reason Setpoint Maume Factor (pCi/g) (pCi/g) (pCi/g) Fraction_____ _____ _ __ _____ ____ (c p m ) (cp m )__ _ _ _ _ _ __ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _46 High BK N/A N/A 4.1 5.80E-02 1.04E-01 5.55E-02 < DCGL 47 Alarm 28,220 47,900 4.1 4.29E-02 1.05E-01 3.84E-02 < DCGL 49 Alarm 28,220 32,000 4.1 3.80E-02 8.86E-02 4.08E-02 < DCGL 50 Alarm 32,150 34,900 4.1 6.39E-02 1.21 E-01 5.30E-02 <DCGL 53 Alarm 30,080 33,600 4.1 4.50E-02 9.26E-02 4.18E-02 < DCGL 55 Alarm 28,220 29,800 4.1 1.12E-01 1.07E-01 4.68E-02 < DCGL 56 Alarm 28,220 29,100 4.1 4.94E-02 8.50E-02 3.02E-02 < DCGL 57 Alarm 28,220 28,900 4.1 3.92E-02 9.32E-02 3.07E-02 < DCGL 58 High BK 26,180 N/A 4.1 5.04E-02 8.28E-02 3.54E-02 < DCGL 59 Alarm 30,080 34,100 4.1 4.83E-02 9.18E-02 3.62E-02 < DCGL 62 Alarm 28,220 31,700 4.1 1.18E-01.

1.12E-01 4.30E-02 < DCGL 63 Alarm 28,220 43,200 4.1 1.23E-01, 1.03E-01 3.70E-02 < DCGL 65 High BK N/A N/A 4.1 1.51E+01 2.46E-01 2.70E+00 3.13E-01 66 High BK N/A N/A 4.1 1.75E-01.

1.12E-01 4.76E-02 < DCGL 67 Alarm 32,150 43,400 4.1 6.06E-01, 8.82E-02 2.03E-01 <DCGL 70 Alarm 30,080 35,300 4.1 4.80E-02 9.91 E-02 2.99E-02 < DCGL 71 Alarm 28,200 30,500 4.1 3.92E-02 8.25E-02 3.14E-02 <DCGL 75 Alarm 26,180 29,200 4.1 3.15E-02 7.60E-02 6.46E-02 < DCGL 80 High Bk N/A N/A 4.1 1.48E+00 1.02E-01 7.04E-01 < DCGL 82 High Bk 26,180 N/A 4.1 8.08E-01 8.80E-02 8.66E-01 < DCGL 86 Alarm 30,080 36,700 4.1 6.90E+00 2.64E-01 1.67E+00 <DCGL 89 Alarm 30,080 32,500 4.1 5.94E+00 1.70E-01 l.llE+OO <DCGL 112 High BK N/A N/A 4.1 1.32E-01 8.48E-02 1.18E-01 < DCGL 117 High BK 26,180 23,200 4.1 6.01E-02 1.02E-01 5.04E-02 < DCGL FR-0400-01, Revision 0 Page 17 of 24 FSS SURVEY RESULTS l INVESTIGATION RESULTS Alarm Scan Area Co-60 Sb-125 Cs-137 DCGLE,%lc Grid Reason Setpoint Measurement Factor (pCi/g) (pCi/g) (pCI/g) Fraction___ ___ ___ _ _ ___ ___ ___ (cpm ) (cpm )_ _ _ _ _ _ _ _ _ _ _ _ _ _140 High BK 26,180 22,100 4.1 7.73E-01 9.10E-02 9.50E-O1 < DCGL 142 High BK N/A N/A 4.1 4.59E-02 8.0 1E-02 3.17E-02 < DCGL 143 High BK N/A N/A 4.1 3.57E-02 6.94E-02 2.73E-02 < DCGL 144 High BK N/A N/A 4.1 3.3 1E-02 7.21E-02 3.25E-02 < DCGL 145 Water 26,180 N/A 4.1 3.14E-02 7.67E-02 3.28E-02 < DCGL 150 Alarm 28,220 29,800 4.1 3.99E-02 8.97E-02 3.55E-02 < DCGL 163 Alarm 26,180 33,600 4.1 6.22E-02 1.1OE-01 4.87E-02 < DCGL 166 High BK 32,150 25,000 4.1 4.43E-02 9.23E-02 3.74E-02 < DCGL 167 Water 26,180 N/A 4.1 4.06E-02 9.42E-02 3.45E-02 < DCGL 168 High BK 28,220 23,400 4.1 6.10E-02 1.14E-01 4.68E-02 <DCGL 169 High BK 28,200 22,500 4.1 2.44E-01 9.40E-02 2.44E-O1 <DCGL 170 High BK N/A N/A 4.1 3.01E-02 6.53E-02 2.9 1E-02 < DCGL 171 High BK N/A N/A 4.1 5.08E-02 1.12E-01 4.61E-02 < DCGL 172 LowBK 30,080 N/A 4.1 1.01E-01 1.IOE-01 5.48E-02 <DCGL 173 Alarm 28,220 30,400 4.1 6.31E-02 1.19E-01 5.47E-02 < DCGL 174 High BK 26,180 21,700 4.1 6.11E-02 1.03E-01 4.17E-02 < DCGL 175 High BK N/A N/A 4.1 5.82E-02 1.19E-01 5.46E-02 < DCGL 176 Unknown 32,150 30,400 4.1 5.1 lE-02 9.22E-02 3.69E-02 < DCGL 194 Alarm 30,080 32,500 4.1 2.93E-02 7.99E-02 3.11 E-02 < DCGL 195 High BK 30,080 29,900 4.1 3.52E-02 8.94E-02 3.63E-02 < DCGL 202 Alarm 32,150 36,200 4.1 4.67E-01 1.05E-01 6.97E-02 < DCGL 203 High BK N/A N/A 4.1 3.17E+00 1.83E-01 5.59E-01 < DCGL 204 Alarm 30,080 37,800 4.1 6.72E-02 1.09E-01 4.57E-02 < DCGL 207 Alarm 24,070 26,500 4.1 2.64E-01 8.97E-02 7.04E-02 < DCGL 215 Alarm 26,180 30,300 4.1 1.72E+00 9.98E-02 3.93E-O1 < DCGL 216 Alarm 26,180 30,500 4.1 1.68E+00 2.26E-01 1.96E-01 < DCGL 217 Alarm 30,080 46,600 4.1 1.53E-01 9.93E-02 5.32E-02 <_DCGL FR-0400-O1, Revision 0 Page 18 of 24 FSS SURVEY RESULTS INVESTIGATION RESULTS Grid Reason Alarm Sca n Area Co-60 Sb-125 Cs-137 DCGL3Mc Setpoin Meaurmen Factor (pCilg) (pCilg) (pCifg) Fraction 218 High BK N/A N/A 4.1 1.80E-01 1.03E-01 7.34E-02 < DCGL 219 Alarm 32,150 38,900 4.1 7.27E-02 1.06E-01 4.79E-02 < DCGL 224 High BK N/A N/A 4.1 3.10E+00 8.74E-02 1.42E+00 <DCGL ISU Mean 5.45E-01 0.OOE+00 3.14E-01 5.45E-02 L _ Total 3.67E-01 NOTES 1. Bolded values are positive detects. All other values are reported at the MDA.2. Activity values are composited results from the 4 m 2 scan grid.3. Area Factors are based on the 4 m 2 area of scan grids.4. Survey unit mean activity values have not been subtracted from investigation results, which is conservative.

FR-0400-01, Revision 0 Page 19 of 24 Attachment 4 Statistical Data FR-0400-01, Revision 0 Page 20 of 24 Survey Package FRO400 Unit 1 Soil Sign Test Summary t9<,-; BEAT -,,;'-e :Evaluation' input;-Valuq sS;A i4- >w !_ n r_ I e Survey Package: FR0400 Forebay I Seal Pit Survey Unit: 01 Evaluator:

DR DCGL,,: 1.OOE+0O DCGLemc: 1.50E+00 LBGR: 5.OOE-01 Sigma: 2.58E-02 (0.31 pCi/g 12.01 pCi/g) Unitized Type I error: 0.05 Type II error: 0.05 Nuclide: UNITY Soil Type: N/A Zap: .1.645 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..p _ _ _ _ ; C atxm itsY,.5 <.'X Number of Samples: 16 Median: 6.51 E-03 Mean: 5.44E-02 Net Sample Standard Deviation:

1.10E-01 Total Standard Deviation:

1.IOE-01 SRSS Maximum: , 4.41E-01 Adjusted N Value: 16 S+ Value: 16 Critical Value: 11 Sign test results: ' Pass Sufficient samples collected:

Pass Maximum value <DCGLw: Pass See Sections D&E of Release Record Median value <DCGL,: Pass Mean value <DCGLw ,- Pass Maximum value <DCGLen,:

Pass Total Standard Deviation

<=Sigma: Investigate See Section F of Release Record Criteria comparison results: ' .,;Investigate See Section I of Release Record ,<- -,t .'1:t,,n s The survey unit passes all conditions:l

5 investigate The SU passes FR0400-SUI-SoilSign 12/17/04 3:53 PM FR-0400-01, Revision 0 Page21 of 24 FR-0400 SU-1 Quantile Plot 0.5-0.45 -_-l C 0.35-o 0- .-_ 0-Activity (Unitized) 0.25-C -Median (Unitized) t-~ : .l0. ___OOl 0.1- __0.1-0.05- _ * *0~0 25 50 75 100 Percent Page/Date/Time Database Variable One-Sample T-Test Report 2 12/17/04 9:58:20 AM C:\Program Files\NCSS97\FR0400SU-1.S0 C2 Plots Section Histogram of FR-0400, SU-1 cm 0 C,.0 E Z 15.II: 8-4-,! .A ,:., , Iw OUt0 6.225 0.250 0.375 0.500 Activity (unitized)

FR-0400-01, Revision 0 Page 23 of 24 One-Sample T-Test Power Analysis Page/Date/Time 2 12/17/04 9:59:15 AM Chart Section Retrospective Power Curve 1.0--- --. --0.8---.*0.6.0.4 -...,. , (II 0.2-0.0 0.2 0.4 0.6 0.8 1.0 Survey Unit Mean (unitized)

FR-0400-01, Revision 0 Page 24 of 24