ML043640313

Maine Yankee Final Status Survey Release Record FR-0400 Forebay Survey Unit 7

ML043640313
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-0400-07, Rev 0
Download: ML043640313 (26)

Text

MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0400 FOREBAY SURVEY UNIT 7 ,;' Date: Prepared By: /2~ Z z //- e *FSS Engineer -Signature~/ e g 1 Il o /^i Pt~d Name Date: Reviewed By: // / a.f zXf 4j/ -a sec -Sig ature Printed Name Date:, Reviewed By: D eirdpcnnt Reviewer -Signature ZPrinted Nam~e Date: Approved By: , 1t pMrintendeO S ign ature' `- 'C/P/rinted Name.Date: Approved By: g ,/ /o PSS, MO0P -Signature Printed Name MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FR-0400 FOREBAY SURVEY UNIT 7 A. SURVEY UNIT DESCRIPTION Survey Unit 7 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 7 consists of the interior of the wvest dike of the Forebay. This is inclusive of a rip-rap layer, sediment and ledge. The area is bounded on its southern extent by the discharge canal, and by the weir to the north. The area includes both above water and submerged portions from the top to the bottom (toe) of the slope. The Survey Unit has a total surface area of approximately 1,550 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 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-0400-07, Revision 0 Page 2 of 26 The survey unit design parameters are shown in Table 1. The values shown in this table reflect those used for the design and implementation of the survey'. Changes to several key parameters (i.e., DCGL and AF) occurred after the survey was complete.

These changes were used to evaluate the data, are discussed in Sections G and 1-1. and shown in Table 2-2.Given a relative shift of 1.6, a minimum number of 17 direct samples were required per the Sign Test. The survey design was based on 20 samples. Twventy-one actually fell within the survey unit. Each sample measurement location was determined using a random start point and a square grid. These locations are presented on survey maps FR 0400-7, FR 0400-07e, and FR 0400-07f (Attachment 1). Direct measurements located above the waterline consisted of soil samples analyzed with laboratory gamma spectroscopy instrumentation.

Measurements located below the water were obtained with in situ gamma spectroscopy (ISOCS).In situ gamma spectroscopy was used to conduct a 100% scan of the area. The survey unit design used the ISOCS portable high purity germanium detector system to perform both underwater and above water scans. Scan grids below water wvere 4m 2.Scan grids above water and below the "bath tub ring" were 12m 2.Grids above the "bath tub ring" were 28 i 2.The "bath tub ring" was the area of high water in the Forebay during plant operation.

The ISOCS detector was positioned with the aid of a prefabricated track and trolley system for measurements below water. Above water measurements were located utilizing a pre-established grid system. This scan survey ensured there were no unevaluated areas exceeding the DCGLEMC limit. The survey instruments used, their MDC values, and investigation levels are provided in Attachment 2.TABLE 1 SURVEY UNIT DESIGN PARAMETERS

[ Survey Unit Design Criteria Basis Area 1,550 mi Based on an LBGR of 3.5 pCi/g Number of Direct 17 20 d Co-60, a sigma 2 of 2.18 pCi/g Measurements Required ( used) Co-60, and a relative shift of 1.6.Type I = Type II = 0.05 Sample Area 77.5 MIn 1,550 rn' / 20 samples Sample Grid Spacings 8.5 m, (77.5)-Area Factor (AF) 10 Scan Survey Area 1,550 m' 100%Background N/A In Situ gamma spec used Scan Investigation Level See Table 2-2 Less than DCGLENIC DCGL 7.0 pCilg Co-60 Forebay Technical Basis Document (Reference 4)DCGLENIC 70 pCi/g Co-60 Area Factor x DCGL 2 Sigma was determined using post remediation survey results.3 Sample spacing of 8.5 was used in the final design. This is conservative and generated 21 direct points when the grid was laid out on the SU map.FR-0400-07, Revision 0 Page 3 of 26 C. SURVEY RESULTS As designed, 21 direct measurements were obtained.

Thirteen measurements consisted of soil samples. Eight measurements were obtained in silve with the ISOCS detector.

The direct measurement data are presented in Table 2 belowv. One of the direct points was above the DCGL. This measurement (S002) was investigated as discussed in Section D.The scan process was performed in accordance with FSS requirements using in sitir gamma spectroscopy.

To achieve approximately 100% scan coverage, 221 ISOCS measurements were obtained.

One of the measurements exceeded the investigation level (i.e., > unitized DCGL). This measurement was evaluated as discussed in Section D.TABLE 2 DIRECT MEASUREMENTS 1Cs-137 Co-60 Unitized Value of Sample Number (pCig (Pci_____________

Unity Rl FRO40007 I SO001 SS 1 .38E-01 + 2.43E-02 < 3.96E-02 I1.82E-03 FRO40007I S002SS 3.25E+00 2.45E-01 5.89E+01 +/- 2.45E+00 1.25E+00 FRO4oo67ISOO3SS__

6.71 E-01 5 .51 E-02 9._73E_+f0h

+/-3.43E-01 1.8913-0 I FR04OOO7 1S004SS5 4.19E-02:h 1-.79E-02 9E02 .051-03 FR040007 1 SOO5S 2.29E-01~

2.94E-02 :h6+0 1.21 E-0OI 6.1 2E-02 FRO40007 I S006SS 1 .50E-01 + 2.57E-02 < 4.17 E-02 I 1.9513-03 F R 040 0 07 ISUPO7SS 3.46E-01 4i 5.OOE-02 3.81E+00+/-~

1.80E-01 8.18E-02 FRO40007ISOO8SS-2.69E-01 3.30E-02 6.111E-O1

+/- 4.06-02 1.48E-02 FR04OOO7 I SO9SS_ 2.47E-01 4.17E-02 I1.16E+00

+ 7.21E-02 2.5913-021 FR0400071ISO lOSS 3.36E-01 4.67E-02 1.61 E+0O + 8.65E-02 3.39E-_072 FR0400071 so0II SS 2.20E-01 ~2.66E.02 1.22E-01 + 1.81E-02 4.12&E-03 FRO40007 ISO I2SS 4.08E-02 1.80E-02 <33E0 .OOE-03 FRO400071SO13SS

< MDA 1.70E-O1 :1 2.38E-02 3.54 -03 FRO400071RO14IG

< MDA 1.88E+00 + 9.58E-01 3.92E-02 FRO400071RO15IG

< MDA 4.69E+00 + 1.25E+00 9.77E-02T FRO40007IRO16IG-

< MDA 7.03E+00 :L 1.90E+00 1.46 -01 F R04 0 0 07 I-RD 1G < MDA 1.91E+00 + 8.01E-01 3.9713-02 FRO400071RO1I 8G <MA< 4.96E-t00 1 .0313-01 FRO4 00071 RO19I G < MDA 9.27E+0O0+/-

1.91 E+0O I1.9313-0I FRO400071RO20IG

< MDA <386E-6 I 8.04E-03-FR040007TRU02 hG- < MDA 2.63E+00 ! 8.41E-0O1 5.47E-02 Mean 2.83E-01 5.28E+00 1.12E-01 Media15n ~4.1 9E-02 1 .88E+00 3.92 -02 Standard Deviation 7.01E-01 1 1.26E+01 2.68E-~1~Range O.OOE+00 -3.25E+00 339E-02 -5.89E+01 L.OOE-03 -1.25E+00 NOTES 1. All values in bold are positive detection values.2. "<" indicates MDA value for non-detect Co-60 results.3. "< MDA" indicates non-detect for Cs-137 results. Refer to Section E for additional discussion.

4. The unitized values were adjusted to account for the contamination depth used in the excavation scenario (60 cm). Refer to Section E for additional discussion.

FR-0400-07, Revision 0 Page 4 of 26 D. SURVEY UNIT INVESTIGATIONS PERFORMED AND RESULTS The scan grid measurement exceeding the investigation level was evaluated to assess compliance with the DCGLEMC unity rule criteria.

This wvas done in conjunction with the direct measurement which exceeded the DCGL. The evaluation is presented in the Investigation Table (Attachment 3). The survey unit passed the EMC test at 32% EMC unity.Following activity adjustment as discussed in Section E, one of the direct points in Survey Unit 7 was above the DCGL of 12.01 pCi/g (S002 was 58.9 pCi/g). The average of the 21 direct measurements wvas 5.3 pCi/g Co-60 and the survey unit passed the Sign Test using unitized values to include the Cs-137. The one location exceeding the DCGL was evaluated using the EMC test.The sample result for S002 was more than three standard deviations above the mean value for the survey unit direct measurements.

The sample was collected from three adjacent, small sediment deposits within an area of approximately 2 feet square. S002 is considered to be an outlier. Based on that determination, an investigation was developed for S002. The sample location was subjected to a long in silz count using a survey area geometry of a I m by 8m rectangle 15 cm thick with gravel placed under rip-rap. The in sitll count result gave a value of 31 pCi/g. The Area Factor for 8 m 2 is 2.8. Re-evaluating the EMC test with an area factor of 2.8 for sample S002 results in a satisfactory result for the unity calculation.

The conclusion is that Sample S002 was an outlier of small size which, when evaluated with its area factor, meets the EMC unity criteria.E. SURVEY UNIT DATA ASSESSMENT RESULTS The Forebay dike soil DCGL was developed assuming that a 2-foot (24") band of soil contamination at the DCGL exists underneath the rip-rap in the Forebay dikes. This 2-foot assumption was arbitrarily made based upon a minimum amount of data. In order to determine the actual extent of contamination within this band of soil, Maine Yankee performed extensive characterization using samples obtained from incline core bores beneath the rip-rap, as close to the rip-rap as possible.

Overall, the Forebay dike soil coring campaign showed that the radiological contamination had not penetrated into the Forebay dikes beyond the rip-rap to any substantial depth (likely less than several inches).ISOCS measurements of the Forebay dike soil through the rip-rap wvere geometrically configured such that the entire photon spectra was attributed to a contaminated soil band of 6 inches. Thus, this activity, attributed to a 6-inch band, should be divided by a factor of four.in order to appropriately compare the results to a DCGL which was developed assuming a 24-inch band of contaminated soil. This adjustment, also applicable to ISOCS measurements above the rip-rap and soil samples obtained at depths of 0" to 6", is justified since the Forebay dike core boring campaign demonstrated that the contamination had not penetrated into the Forebay dike beyond the rip-rap to any significant extent. Therefore, the results for FR-0400 Survey Unit 7 were evaluated as discussed above.FR-0400-07, Revision 0 Page 5 of 26 An analysis of the direct sample measurement results, including the mean, median, standard deviation, and sample result range are provided in Table 2. Positively detected values are bolded in the table. Since Co-60 is the primary radionuclide of concern, non-detect values were assumed to be present at the MDA. Non-detect values for Cs-I 37 were assumed not be present.The sampling results yielded eight measurements with both Co-60 and Cs-1 37, four measurements with only Cs-137, seven measurements with only Co-60, and two samples with no plant-derived activity.

The right hand column in Table 2 is the DCGL unity column.The survey unit mean value in this column indicates that the direct measurements were at 11.2% of the DCGL limit. One direct measurement exceeded the unitized DCGL by approximately 25%. This location (S002) was investigated and found to be acceptable.

The sigma for the direct measurements was also evaluated.

If the sigma is calculated without the sample outlier (S002), the result is 2.9 pCi/g as compared to a design sigma of 2.2 pCi/g.Using the new standard deviation and revised Co-60 DCGL, the revised relative shift would be 2.0 verses a design value of 1.6. Therefore, the increase has no impact on the survey design and a sufficient number of samples were obtained.One scan (ISOCS) location and one direct measurement were investigated/evaluated, as shown in Attachment 3, and determined to be less than 32% of the Elevated Measurement Comparison unity limit, thereby satisfying the EMC criterion.

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 established, mean fallout Cs-137 background value of 0.19 pCi/g (Reference

5) for distributed soil from the survey unit mean (0.28/4 = 0.07 pCi/g) yields a negative value which is equivalent to 0.0 mrem/y. Since there is no background value for Co-60, the annual dose contribution from this radionuclide is 1.0 mrem/y (= 5.28 pCi/g /4 x 1 /12 pCi/g x 9 mrem/y). However, for the purposes of demonstrating compliance with the radiological criteria for license termination and the enhanced State criteria, background activity is not subtracted from the sample analysis activity values.FR-0400-07, Revision 0 Page 6 of 26 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.1. The Sign Test Summary provides an overall summary of design input (Table I) 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 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. All but one 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 direct measurement values. -This plot shows that the direct data were essentially a skewed 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 fraction of the DCGL has an adequate probability

("power")

of meeting the release criteria.

Thus, it can be concluded that the direct measurement data support rejection of the null hypothesis, providing 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 TIHE EXTENT OF RESIDUAL ACTIVITY The dose model originally assumed 24 inches of contaminated soil behind the rip-rap on the dike walls. Based on data from the core boring campaign, the depth was 2 inches or less.The ISOCS values were divided by a factor of four to adjust depth to 6 inches. In addition, the entire 10 mrem/y was assumed because there wvere no other contributing sources.FR-0400-07, Revision 0 Page 7 of 26

11. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit 7 was designed and performed using the criteria of the approved Forebay Technical Basis Document (Reference

4) and LTP Revision 3 Addenda (Reference I and 2). Subsequent LTP changes have been evaluated and have no impact on the design, conduct, or assessment of the final status survey of this Survey Unit. However, during final data evaluation, Survey Unit 7 had issues related to the EMC unity rule criteria.

As a result the Forebay soil excavation scenario was modified to increase the Forebay soil DCGL to a value which was equivalent to the entire 10 mrem/y (9 actually used) limit allowed for soil outside the RA. This change raised the DCGLs for Co-60, Cs-137, and Sb-125 to 12.01, 34.76, and 69.52 pCi/g, respectively.

These changes are documented in Reference

6.1. 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. The direct measurement results pass the Sign Test.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.The Retrospective Power Curve shown in Attachment 4 confirmed that-sufficient samples wvere 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 a skewed distribution with one outlier, with variance consistent with expectations for a Class 1 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 one verified alarm. Attachment 3 shows the elevated areas identified and provides the results of the investigation actions. The areas under investigation were evaluated using the appropriate area factor. Elevated measurements were evaluated and determined to satisfy the elevated measurement comparison unity rule per LTP methodology.

It is concluded that FRO400 Survey Unit 7 meets the release criteria of IOCFR20.1402 and the State of Maine enhanced criteria.FR-0400-07, Revision 0 Page 8 of 26 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-03-05 1, "Forebay Technical Basis Document," dated September 3, 2003 5. Approach for Dealing with Background Radioactivity for Maine Yankee Final Status Surveys, Attachment E to Maine Yankee Procedure PMP 6.7.8, FSS Data Processing and Reporting 6. Maine Yankee Calculation EC-041-01, Diffuser and Forebay Dose Assessment

7. Maine Yankee Calculation EC-003-04, Use of Canberra In Situ Object Counting System (ISOCS) for FSS Surveys FR-0400 07, Revision 0 Page9of26 Attachment I Survey Unit Maps FR-0400-07, Revision 0 Page 10 of 26 Maine Yankee Alaine Yankee DeconPntissioningProjectVurvey Fo Map ID #: FRO400 SITE Decommissioning Team Name: FRevised:

11-0-03 Survey Type: 17l Rernediation El Turnover U Final Status Survey I Survey Area Name: Forebay Site Map 623,000 E 623,500 E 624,000 E 624,500 E 625,000 E 4)8 a-4 z 0-4 J.I 01 2 4o a 8 z I o SCALE 0 400 800 1200 Note: Grid based on Maine State Coordinate System (West Zone) NAD 1927 MN 1- -: N FR-0400-07, Revision 0 Page II of 26 az E;t I.E E we*z 5 r 0 r_0.: to.I 4 t- g 2 a)m = 2 4a,' I oC1)CO)---.--- -----1 5 1ODO -------S S0 0 4 S O O .***....'%~, *.so~osSOO EGGED n0 v V ~ ' R Q2 / .4 R 015 *'/ -____Rack So sdm D::. -Do2 e m n o I n ".0 4R aim (L)Sqm GMZd*W016 Dda PohLoci AN commionine g Mae Yankee Dromsioig Pec Survey Form MaP Id 12-16 04 Dcmmisine Yake MIneYne eom isoigI Revied 12-FR 0407 Survey Type: 0 Characterizaton 0 Tumover E Final Status Survey I Survey Area Name: Forebay, West Dike FR 0400: FOREBAY Survey Unit 7, North Section of West Bank Direct Points SO I -S007, S0 1 3 and R 01 4 -R 01 9*- --*S004 sool..S00 005S003 4, L- .17- ---OR0 *R1 -*01 ..--- -----U*S013-. ' -rT U I -U.. 1{)FOREBAY LECEND pD ___kankE at-..... --. R~Rsp Ews ~k...............

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• Bom.* S.5rm(L) quu'G rdd*W016 Dwrdpo~lAOmW 9 .o.V.V a FR-0400-07, Revision 0 Page IS of 26 SAwl550sq-4n Scale:1"30 Maine Yankee aine Yankee Decommissioning Project Surey Form Map ID it FR 0400-07a Decommissioning Team I ,,e Ie Revise: 12-15-04 Survey Type: O Characterization 0 Turnover H Final Status Survey I Survey Area Name: Forebay, West Dike FR 0400: FOREBAY Survey Unit 7, North Section of West Bank Underwater ISOCS Frames 1 thru 8 M1

• _ -4_TYIC ISC INEWTRLClO-ITidy PO~dW -Er Z-t+ITdley Posidban 20.I Trdfey PotWaiW 2 0 4 TmlI~y Pooeaim W.j1.I ,': .I ,~ .,.I I.-II -(LWONG AT SLOPE)I_ .. .. .....FOREBAY I.'.LEGEND__ ~Ro dcm* nEx I -v -IO In I (BoSp*ad=)

FR-0400-07, Revision 0 Page 16 of 26/Scale: 11-I Maine Yankee Maine Yankee DecommissionIng Project Survey Form MapID*. FR 0400-07b Decommissioning Team I I eeRevised:

12-15-04 Survey Type: 0 Characterization 0 Turnover 1 Final Status Survey I Survey Area Name: Forebay, West Dike FR 0400: FOREBAY Survey Unit 7, South Section of West Bank Underwater ISOCS Frames 9 thru 16 i !W TYPICAL LSOCS UNDERWATER LOCATION (LOKING ATSW I os':'~' ',.:..........

-'. '.: fto lft E LECEND Rock *Bdwd R _ u* Ex. (Bo* Bom)Ledse t -Ap Om IS= Ri SpeV-N FR-0400-07, Revision 0 Page 17 of 26 Scale: 1" Attachment 2 Survey Unit Instrumentation FR-0400-07, Revision 0 Page 18 of 26 TABLE 2-1 INSTRUMENT INFORMATION ISOCS Detcctors (Field Measurements)

I Detector Number I MDC (pCi/g)7605 See Table 2-2 7607 l See Table 2-2 HPGce Detectors (Laborary Analysis)I Detector Number I MDC (pCilg)IlSS-l -0.15 1FSS-2 -0.15 TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, INVESTIGATION LEVEL, AND DESIGN DCGLEAICl Detector I ISOCS I Comments Scan MDC MDC < 70 pCi/g Co-60 Note I DCGL 12.0 pCi/g Co-60 Reference 5____________________

3 34.76 pCi/g Cs- 3 7Rernc5 Investigation Level DCGL < DCGLENIC-DCGLx 1.4 (1.4 is the Design DCGLENIc 48.7 pCi/g Cs-o 37 actual AF for surface 48.7p~ig Cs137 soil, LTP Table 6-12)NOTE 1: The effective activity for non-detect Co-60 is 25% of the reported MDC as discussed in Section E.FR-0400-07, Revision 0 Page 19of26 Attachment 3 Investigation Table FR-0400-07, Revision 0 Page 20 of 26 TABLE 3-1 INVESTIGATION RESULTS Gid l Co-60 Cs-137 (pCilg) (pCl/g) l Area m1 AF Grd(pCilg) (Pcilg) Minus Minus A c 2 Comparison

= l SU Mean SU Mean Fraction S002 3.09E+01 + 12.38% < MDA 2.83E+01 N/A 8.OOE+00 l 2.8 < DCGL 171 5.47E+01 + 6.71% < MDA 5.21 E+OI N/A 4.00E+00 4.1 2.65E-0 1 Survey Unit Mean 5.52E-02 1 Total 3.20E-01* FR-0400.07, Revision 0 Page 21 of 26 Attachment 4 Statistical Data FR-0400-07, Revision 0 Page 22 of 26 Survey Package FR-0400 Unit 7 UNITY Soil Sign Test Summary Hi E onal6 npiutValuesj , ' i- .~;~ 'a t~ -oI-Survey Package: FR-0400 Forebay Survey Unit: 07 Evaluator:

GP DCGL.: 1.OOE+00 DCGL,.: 1.OOE+01 LBGR: 5.00E-01 Sigma: 1.82E-01 Unitized Type I error: 0.05 Type II error: 0.05 Nuclide: UNITY Soil Type: N/A Z * , 1.645 Z-rP- 1.645 Sign p: 0.99379 Calculated Relative Shift: 2.7 Relative Shift Used: 2.7 Uses 3.0 if Relative Shift is >3 N-Value: 12 N-Value+20%:

1 5 i ' Sample DataValues

-.i ;Corient At '1 ;I':4t Number of Samples: 21 Median: 3.92E-02 Mean: 1.122E-01 Net Sample Standard Deviation:

2.68E-01 Total Standard Deviation:

2.68E-01 SRSS Maximum: 1.25E400 Adjusted N Value: 21 S+ Value: 20 Critical Value: 14 Sign test results: -Pass 1 ;1.:.-..i;-,f'~teaSat'f&cj-v jm is'r i$17&mt ,,,@.Sufficient samples collected:

! : Pass Maximum value <DCGLw: Investigate See sections D & E of Release Record Median value <DCGL,: Pass Mean value <DCGL,: Pass Maximum value <DCGLc,: Pass Total Standard Deviation

<=Sigma: ' lnvestigate See section E of Release Record Criteria comparison results: ...-. Investigate See section I of Release Record s- SW a t-tt -- .F~l S;4.A,sOtS It al;.The survey unit passes all conditions:

l :- i:investigate The SU passes.FR-0400-SWJ-SoiISign-UNITY 12114/04 1:10 PM FR-0400-07, Revision 0 Page 23 of 26 FR-0400 SU-7 Quantile Plot 1.4 1.2-r X Io0 0-0 (F 0 0 0 u" x tj <CsF")N-.-.5._O: 1-0.8-0.6-0.4-* Activity (Unitized)., L Median (Unitized)

._ _ .... ... ....0.2 0-I-----..-.._ ; I I *

• v --0 25 50 75 100 Percent Page/Date/Time Database Variable One-Sample T-Test Report 2 12/14/04 12:57:32 PM C:\Program Files\NCSS97\FR0400SU-7.S0 C2 Plots Section Histogram of FR-0400, SU-7 25.CM E 0)C.E M.0 E 19-13-6--1-11 i, 0.o00 0.350 0.700 1.050 i.400 Activity (unitized)

FR-0400-07, Revision 0 Page 25 of 26 One-Sample T-Test Power Analysis Page/Date/Time 2 12/14/04 1:01:43 PM Chart Section L_.a)~0 a-1.0 .0.8 0.6 0.4 0.2 0.0 _0.1 Retrospective Power Curve..- ..l 0.3 0.5 0.7 Survey Unit Mean (unitized) 0.9 1.1 FR-0400-07, Revision 0 Page 26 of 26