ML051050067

Final Status Survey Release Record FD-3500 Storm Drains Survey Unit 1

ML051050067
Person / Time
Site:	Maine Yankee
Issue date:	04/07/2005
From:	Olsen C, Packer J, Pillsbury G, Randall D Maine Yankee Atomic Power Co
To:	NRC/FSME
References
FD-3500-01, Rev 0
Download: ML051050067 (24)

Text

MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FD-3500 STORM DRAINS SURVEY UNIT 1 Prepared By: Ha 9 ,S4 Date:  %- 7-QS FSS Engineer- Signature Printed Name Reviewed By: Date: 2j Igos FSS Sj aR -)ignature Printed Name Reviewed By: _ Date: 0 /i i Independent Revlew - Signature Prfnte N Approved By: 4 O S Date: _q Pperinten ted N eiature Prin'ted Name/

Approved By: AhzX Date: 4fi/z jezS. MOP - Signature Printed Name Revision 0

MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FD-3500 STORM DRAINS SURVEY UNIT 1 A. SURVEY UNIT DESCRIPTION Survey Unit 1 is a portion of Survey Area FD-3500, the Storm Drains survey area. The Storm Drains accommodated the overboard discharge of surface water through buried piping of varying diameters and material types across the developed portion of the site.

Survey Unit 1 consists of the piping leading into Outfalls 11 and 12. These outfalls correspond to Storm Drain Sections 3 and 4 as described in References I and 7. Outfalls 11 and 12 and the associated piping are shown in relation to other major site structures and the Maine State Coordinate System (West Zone) NAD 1927 in map FD 3500 SITE. All maps referenced in this release record are provided in Attachment 1 unless otherwise noted.

Specific piping layout and information is shown on map FD 3500-1 REF. The survey unit is approximately 346 in 2 .

B. SURVEY UNIT DESIGN INFORMATION The survey area consists of Class 1 and Class 3 piping sections. Survey Unit 1 was classified as a Class 3 survey unit; the classification of individual piping sections was based on their potential for contamination, this determination was based primarily on location. The survey classes for particular sections are specified in Attachment 5A of the License Termination Plan (LTP, Reference 1).

The survey unit design parameters are shown in Table 1. Given an adjusted relative shift of 3.0, it was determined that 14 direct measurements were required for the Sign Test; however, the number of samples was increased because the LTP also requires a minimum of 30 direct samples points (to accommodate an efficient field layout, 32 were taken).

Measurement locations were determined by equally distributing the measurement locations along the bottom half of the circumference and length of the accessible areas of the piping at the outfall. Since this is the lowest elevation of the survey unit, it is considered to be an appropriate location for sampling, as is suggested by the LTP as a key element of the survey design for Class 3 piping. These direct measurement locations are illustrated on the maps FD 3500-Ola and FD 3500-Old. Removable contamination samples were obtained at each measurement location.

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The survey was also designed to include 20 scan grids for surfaces, each of 0.22 m2 (Outfall

12) or 0.37 m2 (Outfall 11) (see map FD 3500-lb, FD 3500-ic, and PD 3500-le). Instrument scan setpoints were set at the DCGL plus background, as shown in Table 2-2 (Attachment 2).

To accommodate measurement geometry requirements for surfaces of differing curvatures (0.116 for 18" ID piping) and damp sample locations (0.043 for damp 18" and 30" ID piping), 43-68 data was evaluated with different efficiencies, as indicated.

Background values were established, for each particular instrument probe application based on local scaler measurements in the survey unit. These background values, listed in Table 1, were used to establish net activity for direct measurements. Material background values were not used.

Since scan measurements are performed in peak hold mode, it is appropriate to apply a peak hold background for calculating scan setpoints. The background applied was the peak hold average ambient value used in determining the material background for concrete (622 cpm)

Reference 8.

The instruments used in this survey are listed by model and serial number in Attachment 2 (Table 2-1). Scan MDCs are also listed in Attachment 2 (Table 2-2) and are compared to the DCGL 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.

In addition to FSS measurements, one sediment sample was removed from each of the first catch basins above Outfalls 11 and 12. These two samples were counted to environmental detection limits by laboratory gamma spectroscopy.

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TABLE I SURVEY UNIT DESIGN PARAMETERS Survey Unit Design Criteria Basis Area 346 my Based on an adjusted LBGR of 8,576 Number of Directdpm/ cm 2 , sigma' of 408 dpm/100 Measurements Required 30 cm2 , and a relative shift of 3.0, Type I = Type 11 = 0.05, N = 14.

Minimum = 30 per the LTP Sample Area N/A Class 3 Sample Grid Spacing N/A Class 3 Scan Grid Area 0.22 m2, 0.37 m2 6 in bands for 18" and 30" diameter piping.

Area Factor N/A Class 3 Scan Survey Area 5.9 m2 (1.7%) Class 3 (1- 10%) required Background f G b 7 § 43-68 Directs 1 789 dpm/100 cm 2 Ambient scaler value (30" diameter dry surfaces) 43-68 Directs 2,005 dpm/100 cm 2 Ambient scaler value (I18" diameter dry surfaces)________________________________

43-68 Directs (30" and 18" diameter 5,408 dprn/l 00 cm 2 Ambient scaler value damp surfaces) 43-68 Scan 3,797 dpm/100 cm 2 Peak hold ambient value (Reference 8)

(30". diameter dry surfaces) ______________________________

43-68 Scan 4,256 dpm/100 cm 2 Peak hold ambient value (Reference 8)

(1 8" diameter dry surfaces)________________________________

43-68 Scan (30" and 18" diameter 11,480 dpm/100 cm 2 Peak hold ambient value (Reference 8) damp surfaces) I Scan Investigation Level DCGL plus See Table 2-2 (Attachment 2 background DCGL 9,800 dpm/100 cm 2 LTP, Rev. 3 Design DCGLEMC N/A Class 3 C. SURVEY RESULTS Thirty-two direct measurements were made in Survey Unit 1. Once corrected for ambient background (material backgrounds were not used) all direct measurements were less than 50% of the DCGL. The resulting data are presented in Table 2 below. No verified alarms were received during the surface scans. Therefore, no investigations were required.

I Design sigma is based an averaging of sigma values from selected areas drained in FD 3500.

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TABLE 2 DIRECT MEASUREMENTS

________J I Gross Sample Location Act' cIvIpy dpm~ll00cm INet Activity I (Table I Background Jdpm./lOO cmSubtracted) 2 FD3500-01-POO1 2,882 1,093 FD3500-01-P002 2,625 836 FD3500-01-P003 2,662 873 FD3500-01-P004 2,521 733 FD3500-01-P005 2,796 1,007 FD3500-01-P006 2,723 934 FD3500-01-P007 2,552 763 FD3500-01-P008 2,607 818 FD3500-01-P009 7,770 2,362 FD3500-01-PO1O 2,418 629 FD3500-01-PO1I 2,363 574 FD3500-01-P012 2,399 611 FD3500-01-P013 7,272 1,864 FD3500-01-P014 2,527 739 FD3500-01-P015 2,466 678 FD3500-01-P016 2,448 659 FD3500-01-P017 2,593 588 FD3500-01-P018 2,066 62 FD3500-01-P019 1,964 -41 FD3500-01-P020 1,929 -75 FD3500-01-P021 2,709 705 FD3500-01-P022 2,046 41 FD3500-01-P023 2,265 260 FD3500-01-P024 2,436 431 FD3500-01-P025 2,620 616 FD3500-01-P026 2,791 787 FD3500-01-P027 2,230 226 FD3500-01-P028 2,319 315 FD3500-01-P029 2,757 753 FD3500-01-P030 2,511 506 FD3500-01-P031 2,593 588 FD3500-01-P032 2,744 739 Mean 2,800 677 Median 2,540 668 Standard Deviation 1,264 483 Sample Range 1,929 to 7,770 -75 to 2,362 FD-3500-01, Revision 0 Page 5,of24

D. SURVEY UNIT INVESTIGATIONS PERFORMED AND RESULTS No investigations were required as there were no verified scan alarms.

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 2,362 dpm/100 cm 2 which is less than 50% of the DCGL.

When adjusted for background, the mean residual contamination level is 677 dpm/100 cm 2 .

This is equivalent to an annual dose of 0.0002 mrem 2 .

There were no verified alarms, and therefore there were no investigations.

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 1) and resulting calculated values used to determine the required number (N) of direct measurements (per LTP Section 5.4.2). The Sign Test Summary is a separate statistical analysis that also calculates the mean, median, and standard deviation of the direct measurements.

The Sign Test Summary table calculated the total standard deviation by propagating the individual standard deviation values used in the subtracted background survey design (using the square root of the sum of the squares method). Therefore, median, mean, and standard deviation values listed in the Sign Test Summary table are slightly different from those listed in Table 2. These differences, however, are minor and have no impact on the statistical analysis or conclusions.

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, key release criteria were satisfied, with one exception. An "investigate" flag was produced because the direct measurement sigma exceeded the design sigma, however, sufficient power is evident, particularly when one considers that 32 samples were taken for the FSS of this survey unit.

2 From Table 6-1 1 of the LTP, the buried piping dose is 2.52E-03 mrem/y, therefore, (677/9,800) x 2.52E-03 0.0002 mremly.

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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 3 survey unit. There is no reason to conclude that the data set represents other than random variations in a Class 3 surface survey unit. It also should be noted that the maximum net activity (2,362 dpm/l 00 cm 2 at location P009) is well below 50% of the DCGL of 9,800 dpm/l00 cm 2 .

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 with two outliers due to damp surface conditions.

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.

As mentioned in Section B, removable contamination samples were obtained at each (direct) measurement location. In that this survey unit involved buried piping area and not a standing building, the removable contamination measurements were not applicable to release decisions for the survey unit. However, the samples were obtained and evaluated, indicating alpha activity less than the MDA values (i.e., < 3.8 dpm/I00 cm2 ) and the beta activity also less than the MDA values (i.e., < 4.8 dpm/l 00 cm2 ). Thus, in comparison with the mean survey unit net activity (Table 2), the removable contamination sampling effort indicated that the majority of activity is fixed. Smears are typically taken immediately after performing direct measurements. Due to an instrument failure, this was not the case in Outfall 11 where measurements were repeated. The removable contamination was negligible; consequently, this has no impact on the validity of direct measurement results.

The analyses of catch basin sediment samples discussed in Section B showed no activity above the MDA values.

G. CHANGES IN INITIAL SURVEY UNIT ASSUMPTIONS ON EXTENT OF RESIDUAL ACTIVITY The survey was designed as a Class 3 area; the FSS results were consistent with that classification. The direct measurement sample standard deviation exceeded the design sigma. However, a sufficient number of sample measurements were taken as discussed in Section F.

H. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The survey was designed, performed, and evaluated from mid 2004 to early 2005 per the criteria of the approved LTP Revision 3 Addenda (MN-02-06 1) dated November 26, 2002.

No subsequent LTP changes with potential impact to this FSS were made.

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I. CONCLUSION The FSS of this survey unit was designed based on the LTP designation as a Class 3 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 50% of the DCGL.

A Sign Test Summary analysis demonstrated that the Sign Test criteria were satisfied. The direct measurement sigma was determined to be greater than that used for design, but a sufficient number of samples were taken to produce adequate power.

The Retrospective Powver 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 3 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. Therefore, no investigations were performed.

In addition, while not part of the release decision criteria, removable contamination sampling confirmed that the majority of remaining activity in this piping survey unit was fixed. The gamma spectroscopy analyses of catch basin sediment samples found no plant-derived nuclides in excess of environmental MDA values.

It is concluded that FD-3500 Survey Unit 1 meets the release criteria of I0CFR20.1402 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-03-049, dated September 11, 2003

5. Issuance of License Amendment No. 170, NRC letter to Maine Yankee, dated February 18, 2004

6. Maine Yankee Calculation EC-010-01

7. Maine Yankee LTP Change No.05-004

8. Maine Yankee Calculation EC-039-01 FD-3500-01, Revision 0 Page 8 of 24

Attachment 1 Survey Unit Maps FD-3500-01, Revision 0 Page 9 of 24

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Maine Yankee Map ID#:FD 3501 Decommissioning Team Maine Yankee DecommissioningProjectSurvey Form Revised: 1/31/05 Survey Type: El Characterization El Turnover X Final Status Survey Survey Area Name: Outfalls 11 & 12 Final Status Survey FD3500 Survey Unit 1: Outfalls 11 & 12

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Maine Yankee Map ID#- FD 3500-01a Decommissioning Team Maine Yankee DecommissioningProject Survey Form Revised: 4/29/04 Survey Type: 0 Characterization 0 Turnover N Final Status Survey SurveyArea Name: Outfall 1 Final Status Survey Outfall 11 Direct Points # P001 - P016 270° 2700 15° 00 End of Drain 2' from End of Drain f 2700  ; 2700 3150 00 00 4' from End of Drain 6' from End of Drain FD-3500-01, Revision 0 Page 12 of 24

Maine Yankee IMap ID#:FD 350' Decommissioning Team IMaine Yankee DecommissioningProjectSurvey ForinIRevised: 6/14/04 Survey Type: O Characterization O Turnover X Final Status Survey I Survey Area Name: Outfall 11 Final Status Survey Outfall 11 Survey Scans P033 - P037 End of J

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-TOP. 0. P-TOP, P036 0 L--TOP,0-P037 FD-3500-01, Revision 0 Total Scan Surface Area for Outfall 11= 3.7 sq-m Page 13 of 24

Maine Yankee I Map ID#: FD 3500-1lc Decommissioning Team IMaine Yankee DecommissioningProjectSurvey Formn Revised: 6/14/04 Survey Type: l Characterization l Turnover 0 Final Status Survey ISurveyAreaName: Outfall11 1=l I1=1 I1=

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P041 P042 P038 P039 P040 FD-3500-01, Revision 0 Total Scan Surface Area for Outfall 11 = 3.7 sq-m Page 14 of 24

Maine Yankee I Map ID#: FD 3500-O1ld Decommissioning Team IMaine Yankee DecommissioningProjectSurvey Form IRevised: 4/29104 Survey Type: 0 Characterization O Turnover U Final Status Survey Survey Area Name: Ouffall 12 Final Status Survey Outfall 12 Direct Points # P017 - P032 2700 9Q0 2700 3150 00 O0 End of Drain 2' from End of Drain 2700 9O0 2700 50 QO 00 4' from End of Drain 6' from End of Drain FD-3500-01, Revision 0 Page 15 of 24

Maine Yankee pID #: FD 3500-le Decommissioning Team Maine Yankee DecomnmissioningProjectSurvey Form Revised: 6/14t04 Survey Type: 0 Characterization O Turnover 0 Final Status Survey Survey Area Name: Outfall 12 Final Status Survey _TYrP. -

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Attachment 2 Survey Unit Instrumentation FD-3500-01, Revision 0 Page 17 of 24

TABLE 2-1 INSTRUMENT INFORMATION E-600 S/N Probe S/N (type) 1928 149071 (43-68 2488 177991 (43-68-5) 1933 177992 (43-68-5)

HPGe Detectors (Laboratory Analysis)

Detector Number MDC (pCi/g)

FSSI 0.03 to 0.04 FSS2 0.03 to 0.04 TABLE 2-2 INSTRUMENT SCAN MDC, DCGL, AND INVESTIGATION LEVEL 43-68 1 Parameter 30"diameter pipe diameter pipe 18" diameter pipe Dry Surfaces Damp Surfaces Dry Surfaces Scan MDC 1,832 5,538 2,053 (dpm/100 cm2 ) LTP Table 5-6 Note I Note 1 (dp CGlOO cm 2 )9,800 9,800 9,800 Investigation Level 13,583 21,225 14,026 (Alarm setpoint) (DCGL plus (DCGL plus (DCGL plus (dpm/100 cm 2) background) background) background)

NOTE: 1. Separate scan MDC developed for the 43-68 when applied to pipe geometry by adjusting the LTP Table 5-6 value for the change in efficiency due to size and/or dampness.

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Attachment 3 Investigation Table (No Investigations Required)

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Attachment 4 Statistical Data FD-3500-01, Revision 0 Page 20 of 24

Survey Package FD3500 Unit I Surface Sign Test Summary a IC-----*_ '; mommen ts '

Survey Package: FD3500 Outfalls 11 &12 Survey Unit: 01 Storm Drain piping Evaluator: DR DCGLW: 9,800 DCGLemc: 9,800 LBGR: 8,576 Sigma: 408 Type I error: 0.05 Type II error: 0.05 Total Instrument Efficiency: 13.0% data adjusted for various effs.

Detector Area (cm2): 126 Choosing 'N/A' sets material Material Type: N/A background to "0' 1.645

-'-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

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Number of Samples: .' ,-32 Median: 669 Mean: _678 Net Static Data Standard Deviation: ,483 Total Standard Deviation: 572 SRSS Maximum: 2,363

.a,'-,, .<.d e omments' - S Adjusted NValue: ,32 S+Value:. . 32 Critical Value:i,. 21 i.-i S Comments Sufficient samples collected: -Pass Maximum value <:DCGL,: .' Pass Median value <DCGL , ' Pass Mean value <DCGL,: Ps Maximum value <DCGL,, : Pass Total Standard Deviation <=Sigma: . 'Investigate SU passes, see section F Sign test results: Pass

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Staftis,,; . commnts The survey unit passes all conditions: ,-Investigate SU passes FD3500-SU I-S urfaceS ign FD-3500-01, Revision 0 3/24/05 1:20 PM Page 21 of 24

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One-Sample T-Test Report Page/Date/Time 2 2/14/05 5:13:27 AM Database C:\Program Files\NCSS97\FD3500 SU-1.SO Variable C2 Plots Section Histogram of FD-3500, SU-1 C,,

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FD-3500-01, Revision 0 Page 23 of 24

One-Sample T-Test Power Analysis Page/Date/Time 2 2/14/05 5:14:08 AM Chart Section Retrospective Power Curve 1.0- .0-_

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FD-3500-01, Revision 0 Page 24 of 24