ML043640209

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Maine Yankee Final Status Survey Release Record FB-2400 Staff Building Tunnel Survey Unit 1
ML043640209
Person / Time
Site: Maine Yankee
Issue date: 12/22/2004
From: Donna Anderson, Litton V, Olsen A, Pillsbury G
Maine Yankee Atomic Power Co
To:
NRC/FSME
References
MN-04-060, RA-04-118 FB-2400-01, Rev 0
Download: ML043640209 (23)
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MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FB-2400 STAFF BUILDING TUNNEL SURVEY UNIT I Prepared By: /Date: l.s4&c. OK FS En incer- Signature Printed Name Reviewed By: \I-L , .Date: IZ-z1 Y FSS S ccialist -ignature ,' CKi L 74Ao-, Printed Name Reviewed By:

  • Date: Ia/. Ii64 Independent Review -Signature a.A,-J &-75 -crintendq

~ ZSignature Approved By: J 9 <. Date: y SS,MOP -Signature Printed Name Revision 0 MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FB-2400 STAFF BUILDING TUNNEL SURVEY UNIT I A. SURVEY UNIT DESCRIPTION Survey Unit I is located in Survey Area FB2400 in the Staff Building tunnel. The tunnel is located on the north side of the Turbine Building at site coordinates 407,712 N and 624,066 E using Maine State Coordinate System (West Zone) NAD 1927. The Staff Building tunnel is shown in relation to other major site structures in map FB 2400 SITE. All maps referenced in this release record are provided in Attachment I unless otherwise noted.During plant operations, the tunnel provided entry to the Turbine Building from the Technical Support Center in the Staff Building basement during emergency drills. It was not used for general personnel access until the plant was being decommissioned.

The survey unit is approximately 153 m 2 and consists of the concrete floor which is approximately 27.4 m in length and includes the lower I m of the wvest and east concrete walls.On the north and south ends of the tunnel are concrete stairs. Following final survey, the concrete stairs on both tunnel ends, the ceiling and a temporary block wall installed for'decommissioning will be removed. Only the floor and approximately I m of lower wall will remain.In addition there is a 0.6 m by 0.6 m concrete sump in the tunnel. The sump is approximately 1.2 m deep.B. SURVEY UNIT DESIGN INFORMATION The Historical Site Assessment initially classified the survey unit as Class 3 per the LTP.During plant operation, the tunnel wvas located outside the Restricted Area (RA) boundaries.

With the onset of decommissioning activities, the RA fence was moved and the southern end of the tunnel fell inside the RA boundaries.

The small portion of the tunnel currently located inside the Restricted Area will be surveyed under survey area FR 0200 after the concrete is removed. Radioactive material was not used or stored in the tunnel; therefore, it was expected to meet the LTP requirements for a Class 3 area. The tunnel configuration and dimensions are provided on map FB2400 SA Ref I (Attachment 1).Tunnel flooding during plant operations was believed to be groundwater influx. However, at one point slightly contaminated Condensate Storage Tank (CST) water flooded the tunnel, perhaps as recently as 1996. A radioactive liquids discharge line passed through the south end of the tunnel during decommissioning, and was removed in September 2004. Its function was to discharge water meeting release limits to the river. In May 2004, it ruptured on overpressure of domestic water supply, flooding the tunnel. Water sample analysis at that time did not identify activity above environmental levels.FB-2400-01, Revision 0 Page 2 of 23 Concrete samples taken in the tunnel for characterization.

notably from the trenches along each wall/floor juncture, indicated activity up to 1.97 pCi/g Co-60 and up to 0.40 pCi/g Cs-2 137. which calculated to a maximum of 444 dpm/100 cm .As a result, the area was reclassified from Class 3 to Class 2.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, but 15 were taken due to the grid map geometry.

Sample measurement locations were determined using a random start point and a systematic square grid. These locations are presented on map FB2400-If (Attachment 1).A 10% to 100% scan coverage is required for Class 2 areas. To meet this requirement, 52 floor grids (approximately I m2), 52 juncture surveys and the floor/wall surfaces were incorporated into the scan design. The total scan area was approximately 57 m 2 or 38% of the survey unit. Scan grids and their locations are shown on maps FB2400-lb through le (Attachment 1).The instruments used in this survey are listed by model and serial number in Attachment 2 in Table 2-1. Scan MDCs are also listed in Table 2-2 of Attachment 2, and are compared to the DCGL and the investigation level. As shown in this table, the scan MDC is less than the scan investigation level in all cases, thus providing high confidence (95% or higher) that an elevated area would be detected in the scanning process. Actual background measurements wvere consistent with design backgrounds used to determine the instrument scan MDC values listed in LTP Table 5-6.Background values were established for the scan measurements based on local values in the survey unit and previously established material background.

These background values listed in Table I were used to establish alarm setpoints, to confirm that the scan MDCs used were appropriate, and to establish net activity for direct measurements.

Instrument scan setpoints were set at the DCGL plus background.

Ninety-degree surface junctures (i.e., wvall-floor) were scanned using the 43-68 probe with a reduced efficiency.

FB-2400-01, Revision 0 Page 3 of 23 TABLE I SURVEY UNIT DESIGN PARAMETERS Survey Unit Design Criteria Basis Area 152.55 m' Class 2, < 2,000 m'Based on an adjusted LBGR of 16,857 dpm/O00 cm 2 , Numer t 14 sigmal of 381 dpm/1 00 cm 2 , Measurementsl and a relative shift of 3.0.Type I = Type II = 0.05 Sample Area 10.9 m 2 152.55 mi 2/ 14 = 10.9 m 2 Sample Grid Spacing 3.3 m (10.9)1/lScan Grid Area I m' or less Class 2 Area Factor N/A Class 2 Scan Survey Area 57 in' (38%) Class 2, 10% -100%Background m >tZ: k.Y ., '. ol:' *43-68 Direct and Scan 3,169 dpm/100 cm 2 Ambient and Material 43-68 Sctn 5,952 dprn!l 00 cm 2 Ambient and Material 43-68 Scan 7,127 dpm/I00 cm2 Ambient and Material (damp concrete) 7 Scan Investigation Level DCGL plus Background See Table 2-2 (Attachment 2)DCGL 18,000 dpm/100 cm' References 2 and 3 Design DCGLEMC N/A Class 2 C. SURVEY RESULTS Fifteen direct measurements were made in Survey Unit 1. All direct measurements wverc less than the DCGL. The direct measurement data are presented in Table 2.No verified alarms occurred during the surface scans (i.e., flats and junctures).

No investigations were required.Two of the scanned grids (C052, C078) had small areas of 100 cm 2 each that were noted as being damp by the survey technician.

The logged results were 886 and 962 cpm respectively.

While the "43-68 Damp Concrete" setpoint of 1550 cpm was not used for these grids, the results were considerably below this. Thus, no resurvey was necessary.

Design sigma is based on LTP Table 5-1 B, Staff Building Tunnel, B2400, (LTP, Rev. 3).FB-2400-01, Revision 0 Page 4 of 23 TABLE 2 DIRECT MEASUREMENTS Gross Activit Nct Activity Sample Location G ross cm (Table 1 Background Subtracted) dprn/00 cmdpmflOO cm 2 FB2400-1-COOI 3669 500 FB2400-1-C002 3071 -98 FB2400-1-C003 3205 36 FB2400-1-C004 3065 -104 FB2400-1 -Coo5 2882 -287 FB2400-1-C006 2949 -220 FB2400-1-C007 3297 128 FB2400-1 -C008 2106 -1062 FB2400-1-C009 2705 -464 FB2400-1-CO10 2906 -263 FB2400-1-CO1 1 2821 -348 FB2400-1-C012 3101 -67 FB2400-1-C013 3278 110 FB2400-1-C014 2998 -171 FB2400-1-C015 3150 -18 Mean 3013 -155 Median 3065 -104 Standard Deviation 342 342 Range 2106 to 3669 -1062 to 500 D. SURVEY UNIT INVESTIGATIONS PERFORMED AND RESULTS No verified alarms occurred, no locations of potentially elevated activity wvere identified, and thus no investigations were performed.

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. Without subtracting background, all direct measurement results were below the DCGL. The maximum direct sample result with background subtracted was equivalent to 500 dpmll 00 cm 2.When adjusted for background, the mean residual contamination level is-155 dpml00 cm 2 , equivalent to an annual dose of 0.0 mrem 2.There were no verified alarms and, therefore, no investigations wvere required.2 This annual dose equivalent is based on LTP Table 6-11 which shows the contaminated concrete dose contribution for surfaces contaminated at the DCGL to be 0.301 mrem/y.FB-2400-01, Revision 0 Page 5 of 23 F. ADDITIONAL DATA EVALUATION Attachment 4 provides additional data evaluation associated with Survey Unit 1, 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 is shown in the table, all of the key release criteria were satisfied for the FSS of the survey unit, except the final sigma (total standard deviation).

While the total standard deviation of 413 dpm/l 00 cm 2 exceeded the design sigma of 381 dpm/lOO cm 2 , the increase in sigma would not have affected the relative shift. Therefore, the survey design had sufficient power to reject the null hypothesis so no additional measurements were required.2. The Quantile Plot was generated from direct measurement data listed in Table 2 and indicates general symmetry about the median. The data set and plot are consistent with expectations for a Class 2 survey unit. It also should be noted that the maximum net activity (location COOl) of 500 dpm/I 00 cm 2 was well below the DCGL of 18,000 2 dpm/l 00 cm .3. A Histogram Plot was also developed based on the direct measurement values. This plot shows that the direct data were essentially a normal distribution.

4. A Retrospective Power Curve was constructed based on FSS results. The curve shows that the 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 unit was initially classified as a Class 3, but was reclassified to Class 2 as discussed in Section B. The direct measurement total standard deviation exceeded the design sigma. However, the increase in sigma would not have affected the relative shift. Therefore, the survey design had sufficient power to reject the null hypothesis so no additional measurements were required.FB-2400-01, Revision 0 Page 6 of 23 HI. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit I was designed and performed in September and October 2004 using the criteria of the approved LTP Revision 3 (References 3 and 5). There have been no subsequent LTP changes with potential to impact this FSS.1. CONCLUSION The FSS of this survey unit was designed based on the LTP designation as a Class 2 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 beta direct measurements were less than the DCGL of 18,000 dpmfl 00 cm 2.A Sign Test Summary analysis demonstrated that the Sign Test criteria were satisfied.

The direct measurement total sigma was determined to be greater than that used for design, however a sufficient number of samples were 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 normal distribution, with variance consistent with expectations for a Class 2 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 no verified alarms for evaluation.

It is concluded that FB2400 Survey Unit 1 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, Maine Yankee letter to the NRC, MN-02-048, October 15, 2002 2. Maine Yankee License Termination Plan, Revision 3 Addenda, Maine Yankee letter to the NRC, MN-02-06 1, November 26, 2002 3. NRC letter to Maine Yankee, February 28,2003 4. Maine Yankee letter to the NRC, MN-03-049, September 11, 2003 (LTP Supplement to LTP Revision 3)5. Issuance of License Amendment No. 170, NRC letter to Maine Yankee, dated February 18, 2004 FB-2400-01, Revision 0 Page 7 of 23 Attachment I Survey Unit Maps FB-2400-01, Revision 0 Page 8 of 23 o 0%0 0.6 0 0%J %4 0 co 4 0 a)0 D.6 0~0 0 0 (A 0 0 0 0 0 uL 0 0 ru 0 0 0 LA 0 0 0 0 0 O 0 0 0 0 0 LA 0 0 623, 000 E 623, 500 E 624.000 E 624. 066 E 624.500 E 625, 000 E MN N 625, 500 E S: 626, 000 E SURVEY AREA, FB 2400 South East Comer of Staff Building Tunnel at Coordinate

-407,712N-624,066E Note: Grid based on Maine State Coordinate System (West Zone) NAD 1927 Final Status Survey FB2400: Staff Building Tunnel (El. 13')Surface Area Reference Map cn C CD-4q CD 0 CD 0 0 3 K.(0 o-' CD CD--- C CD 7 S I W I ________C-)w 5.W~U~AST PAD 1-tx U1---... .. '. -.-I , I -, I .., LOOKING WEST 453.7 sq-ft (42.15 sq-rn)0n 0 0j D5 CD 0.) > ..,-. .'I SLAB 599.0 sq-ft (55.65 sq-rn)11-4 0 3-5,, C (I,;2 CD CD 5.-4 C)CD b..4 ti.i9:)C~Q Cn..... .- t , " -. '. .-.... I .I .. -1. I -1. -.-...-- ..-... , --, '.. .. ._ T, --.., -.. ..i r BELOW 31 BELOW GRADE LKKAD RAD W.STE L.9 _,0/ 71--z' z Z , I .1 7/ I. .I ; .......j , -.. 1. .1 ..1 I LOOKING EAST 453.7 sq-ft (42.15 sq-rn)Approx. 86' 10'(2 (42.15) + 55.65 + 3.3 [S Wall] + 2.7 [Sump] + 6.6 [N Wall]) sq-rn = 152.55 sq-rn Total Area <3' Grade.1.

Final Status Survey FB2400: Staff Building Tunnel (El. 13')Direct Points 001 -015 a-> N w (~j-VZ w C>0 0 LOOKING WEST--------------------------------------I r ----------------------------I I; : m I 11 I I ------- -I -__ -OT1 -----------SLAB N = 14 L = 3.3 Total Area <3' Grade = 152.55 sq-m Maine Yankee ..I Map ID #: FB2400-1b Decommissioning Team Aaite Yankee Decomiiiiiissionitg Project Swrvey Form Date: 10/12/04 Survey Type:-Characterization

_ Turnover L Final Status Survey Survey Area Name: Staff Building Tunnel Final Status Survey FB2400: Staff Building Tunnel (El. 13')Survey Scans 001-052>D-> N----- F-,-7--T---

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10241 0211 02010171 0161 0131 0121 0091 0081 0051 OC 1- 1 02210191 0181 0151 0141011 0101 00710061 I I L L --+ ----- -- ---- ---L: ------C TRENCH I SLAB, N End I K F ----- F --F F F F T 1 10521 049104810451044 1041104010371036103310321029102810251, 4 1051105010471 04610431 0421 0391 0381 0351 034103110301 0271 0261:-VL -- ----: ---z L L'SLAB, S End (j TRENCH -FB-2400-0 1, Revision 0 Page 12 of 23 Maine Yankee ...Map ID #: FB2400-lc Decommissioning Team Mliane Yanikee Decomittinssionitng Project Survey Form: I Date: 10/12/04 Survey Type: -Characterization

) Turnover L Final Status Survey I Survey Area Name: Staff Building Tunnel Final Status Survey FB2400: Staff Building Tunnel (El. 13')Juncture Survey Scans 053-078 ow DE--LOOKING WEST, NORTH END* .C. S ... ......4 cXs LIQUID RAD-WASTE LINE-J_LOOKING WEST, SOUTH END FB-2400-01, Revision 0 Page 13 of 23 Maine Yankee Map ID #: FB2400-1d Decommissioning Team Maie Yankee Decommissioing Project Survey Fori IDate: 10/12/04 Survey Type: -Characterization

-Turnover X Final Status Survey I Survey Area Name: Staff Building Tunnel Final Status Survey FB2400: Staff Building Tunnel (El. 13')Juncture Survey Scans 079-104.., ., ... .. ....~~~~~~a .e.... ...........LIQUID RAD _WASTE LINE-M ; I N I '% I A7 1 -7 , , , 7 , 7 , N -% r --=- ---%F-T- - ---T- ---------T- ---r- ---- --------r- --7`1 , 091 , 092 , 093 , 094, 095, 096, 097, 098, 099,100,101 102 103 104 L.-I- ... .I ..- .-... .. F .-...1 -' .... -..LOOKING EAST, SOUTH END 3B GF LOOKING EAST, NORTH END FB-2400-01, Revision 0 Page 14 of 23 Maine ankeeMa p ID It. F132400-le Maine Yankee m laUiri' Yainkee DecommiSSioiting Project rSrvLer Fol-ui Date: 10/12/04 Decommissioning Team Tuu Survey Type '-hrcerzto Turnover X Final Status Survey lSurvey Area Name: Staff Bulding nTunnel Final Status Survey FB2400: Staff Building Tunnel (El. 13')Survey Scans 105-109 West Sump Wall 0)_QO South Sump Wall 108 Sump Bottom 106 North Sump Wall 0o N)East Sump Wall FB-2400-01, Revision 0 rag I-Ju VI ZJ Attachment 2 Survey Unit Instrumentation FB-2400-01, Revision 0 Page 16 of 23 TABLE 2-1 INSTRUMENT INFORIIATION l E-600 S/N I Probe S/N (type)1625 148931 (43-68)1625 148937 (43-68)1641 148939 (43-68)1648 149069 (43-68)TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, AND INVESTIGATION LEVEL D ctor 43-68 43-68 43-68 I D (Flats) J (Junctures) j (Damp Concrete)Sean MDC 1,832 3,969 4,860 (dpm/lOO cm 2) (Note 1) (Note 2) (Note 2)DCGL 20 CM2) 18,000 18,000 18,000 (dpm /1 00 c )_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _Investigation Level 21,184 23,942 25,105 (Alarm Setpoint)

(- DCGL plus (- DCGL plus (- DCGL plus (dpm/1 00 cm2) background) background) background)

NOTES 1. LTP Table 5-6 2. The 43-68 Scan MDC from LTP Table 5-6 was adjusted to account for a change in efficiency due to geometry or surface condition.

FB-2400-Ol, Revision 0 Page 17of23 Attachment 3 Investigation Table (No Investigations Required)FB-2400-01, Revision 0 Page 18 of 23 Attachment 4 Statistical Data FB-2400-01, Revision 0 Page 19of23 Survey Package FB2400 Unit I Surface Sign Test Summary Es , :ldtionInpijtValues' 1- 2> B;r2nComen ts i Survey Package: FB2400 Survey Unit: 01 Evaluator:

CAO DCGL-: 18,000 dpm/100cm2 DCGL,,,: n/a Class 2 LBGR: 16,857 dpmllOOcm2 Sigma: 381 dpm/100cm2 Type I error: 0.05 Type II error: 0.05 Total Instrument Efficiency:

13.0%Detector Area (cm 2): 126 Concrete Material Type: Unpainted Choosing 'N/A' sets material background to "0"§;.>,i C -r.,Xsalculated Values O k t C 1.645 Za: 1.645 Sign p: 0.99865 Calculated Relative Shift: 3.0 Relative Shift Used: 3.0 Uses 3.0 if Relative Shift >3 N-Value: 11 N-Value+20%:

14 W¢>- se;>xrStatiCDaaaloAmfv

ttt -
A; W6 --, omme'n s' t Number of Samples: 15 Median: -104 dpmlOOcm2 Mean: -155 dpm/100cm2 Net Static Data Standard Deviation:

342 dpm/100cm2 Total Standard Deviation:

413 SRSS Maximum: 500 dpml100cm2

>,~&~-;S,.&eSign -et Re' ula-+t,*;

+t,, >,,;omm~on

,+~-,,t9v4 Adjusted N Value: 15 S+ Value: 15 Critical Value: 11 Sufficient samples collected:

Pass Maximum value <DCGL,: Pass Median value <DCGL: Pass Mean value <DCGL,: Pass Maximum value <DCGLenc : Pass Total Standard Deviation

<=Sigma: Investigate Sufficient power to reject the null hypothesis Sign test results: Pass The suNrvy unit pasiesal cStotiois:

1'.,'i,{,, ,*-. Invesigate, The survey unit passes all conditions:

-1 Ivestigatel FB2400-SU1-SurfaceSign.xis FB-2400-01, Revision 0 Page 20 of 23 12/211046:27 AM FB-2400 SU-1 Quantile Plot 600-r t'3-PO eQ 0" a>'0 Caq E 0 CD To 0.._I-0 400 200 0-200-400-600-800-1000., ., .I I ', W ,.*Activity cm2)(dpm/1 00-Median (dpm/100 cm2)..-1200 0 25 50 75 100 Percent Page/Date/Time Database Variable One-Sample T-Test Report 2 12/13/04 9:02:58 AM C:\Program Files\NCSS97\FB2400 SU-1.S0 C2 Plots Section Histogram of FB-2400, SU-1 Cl)Q, E co Activity (dpm/100 cm2)FB-2400-01, Revision 0 Page 22 of 23 Page/Date/Time 2 12/13/04 Chart Section L-a)~0 a-Retrospective 1.04 ---0.8 ---0.6- .---0.4 ---0.2 One-Sample T-Test Power Analysis 9:04:08 AM Power Curve., ----I_-5d00 0 5soo 10600 15600 Survey Unit Mean (dpm/100 cm2)20600 FB-2400-01, Revision 0 Page 23 of 23

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