ML043290338
| ML043290338 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 11/17/2004 |
| From: | Pillsbury G Maine Yankee Atomic Power Co |
| To: | NRC/FSME |
| References | |
| FB-3000-01, Rev 0 | |
| Download: ML043290338 (19) | |
Text
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FB-3000 SEWAGE TREATMENT PLANT SURVEY UNIT 1 Prepared By:
jSEngine -, i ,ure rinted Name Reviewed By: <71gnatur FSS ignatur Printed Name A A. ~ Date:
Reviewed By: e. at /0 ES.,0 Independent Reviewer -
Signature De le Kf 4 a /*of
,,PrintName Approved By: D 4'u MnO1 -Signature Date:
Printed Name/
Approved By: Date
>,//v 7
'FSS, IN10f - Signature o Printed Name
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FB-3000 SEWAGE TREATMENT PLANT SURVEY UNIT 1 A. SURVEY UNIT DESCRIPTION FB-3000, the Sewage Treatment Plant (STP), is a concrete, below-grade structure that is located on the east side of Bailey Point adjacent to and north of the former Circ Water Pump House at Maine State Grid Coordinates 624400 E and 407630 N (See map FB-3000-001, Attachment 1). The structure contained waste holding and treatment tanks and equipment which were used to treat sanitary waste before Maine Yankee connected to the Wiscasset municipal treatment facility. The survey area consists of a single survey unit. Survey Unit 1 consists of the concrete walls (up to grade 17 feet) and floor and comprises a surface area of approximately 226 m2 . The survey area was located outside of the plant's radiologically restricted area (RA).
B. SURVEY UNIT DESIGN INFORMATION FB-3000 Survey Unit I was designated a Class 3 survey unit per the Maine Yankee Area Classification Basis Document. Prior to 1985, the STP processed all of the site sanitary waste. Up until the early 1980s sewer drains from the RA were directed to the STP.
Evaluation of HSA and characterization data resulted in the Class 3 determination.
The survey unit design parameters are summarized in Table 1. Given a relative shift of 3.0, it was determined that 14 direct sample points were required for the Sign Test. Measurement locations were randomly generated for Survey Unit I and are shown on map FB-3000-003 (Attachment 1). Once the direct readings were completed, removable contamination samples were obtained at each measurement location.
A 1% to 10% scan coverage of the area was required.' Scan grids were typically I m2 areas around the direct measurement locations plus an additional 9 m2 in and around the sump as shown on map FB-3000-004 (Attachment 1). The total scan area was approximately 23 m2 ,
thus meeting the upper scan coverage requirement of 10%.
The survey instruments used, their scan MDC values, and alarm setpoints are provided in Attachment 2. As shown in Attachment 2, the scan MDC is less than the investigation level, which provides a high confidence level (95%) that an elevated area would be detected by scanning.
Background values were established, for each particular instrument probe application based on ambient background values in the survey unit and previously established material backgrounds. These background values, listed in Table 1, were used to establish net activity for direct measurements and to confirm the scan MDCs used were appropriate.
LTP Table 5-3 FB-3000-01, Revision 0 Page 2 of 19
TABLE 1 SURVEY UNIT DESIGN PARAMETERS Survey Unit Design Criteria Basis Area 226 m2 No limit for Class 3 Area Based on adjusted LBGR of 14,844 dpm/100 cm 2 , sigma2 of Number of Direct 14 1052 dpm!100 cm 2, and Measurements Required 14 105 m n lp/
relative shift of 3.0 l_ Type I = Type II = 0.05 Sample Area N/A Class 3 Area Sample Grid Spacing N/A Class 3 Area Scan Grid Area I m' (a 2 m area around the Class 3 Area I_ sump was also scanned)
Area Factor N/A Class 3 Area Scan Survey Area 23 m2 Class 3 Area I% - 10%
Background
6 DAmbient plus Material 43-68 Direct and Scan 2,411 dpm/100 cm 2 Material Background from (flat surfaces) EC-039-01 (Reference 1)
Scan Investigation Level 0.5 DCGL (See Table 2-2) EC-009-01 (Reference 5)
DCGL 18,000 dpm/1 00 cm2 LTP Revision 2 for concrete esgDCGL 18,000 pm~l cm N surfaces Design DCGLEMc N/A Class 3 Area C. SURVEY RESULTS Fourteen direct concrete measurements were taken with the results provided in Table 2. All direct measurements were less than the DCGL. Removable contamination measurements were all less than the MDA values.
No scan alarms were received; therefore, no investigations were required.
2 LTP Attachment 2B and MY Calculation EC-032-01 (Reference 6)
FB-3000-01, Revision 0 Page 3 of 19
TABLE 2 DIRECT MEASUREMENTS Sample Number b Gross Activity (dpm/100 cm 2 ) Jl Net Activity*
(dpm/100 cm2)
FB3000-1-C001 1673 -739 FB3000-1-C002 2234 -177 FB3000-1-C003 2173 -238 FB3000-1-C004 2118 -293 FB3000-1-C005 2143 -269 FB3000-1-C006 2100 -311 FB3000-1-C007 2509 98 FB3000-1-C008 2418 6 FB3000-1-C009 2369 -43 FB3000-1-C010 2650 238 FB3000-1-COI1 2411 0 FB3000-1-C012 2497 85 FB3000-1-C013 2564 153 FB3000-1-C014 2289 -122 Mean l 2296 -115 Median 2329 -82 Standard Deviation 251 251 Range 1673 -2650 -739 -238
- Table I background value subtracted D. SURVEY UNIT INVESTIGATIONS PERFORMED AND RESULTS None required.
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 238 dpm/100 2 When adjusted for background, the mean residual contamination level is -115 dpm/l 00 cm2.
This would be equivalent to an annual dose rate of 0.0 mrem/y.
FB-3000-O1, Revision 0 Page 4 of 19
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 is shown in the table, all of the key release criteria were clearly satisfied for the FSS of this survey unit.
- 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 3 survey unit. All of the measurements are well below the DCGL of 18,000 dpm/100 cm2 .
- 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 no outliers.
- 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 a (backfilled) basement 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., < 3.4 dpm/l 00 cm2 ) and the maximum beta activity less than the MDA of 28 dpm/l 00 cm2 . Thus, in comparison with the mean survey unit net activity (Table 2), the removable contamination sampling effort indicated no loose surface activity. In addition, samples of the STP sump water were analyzed by gamma spectroscopy to environmental LLDs with no detectable plant-derived radioactivity found.
FB-3000-01, Revision 0 Page 5 of 19
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 was less than the design sigma. Thus, no additional measurements were required.
H. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit I was designed, performed and evaluated in late 2001. The design was performed to the criteria of the LTP, Revision 2 (Reference 2). Subsequent LTP changes with potential impact to this survey unit were evaluated:
This LTP change was evaluated and found to have no impact on results or conclusions of the FSS for FB-3000 Survey Unit 1.
I. CONCLUSION The FSS of this survey unit was designed based on the 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 the DCGL of 18,000 dpm/100 cm2 .
A Sign Test Summary analysis demonstrated that the Sign Test criteria were satisfied. The direct measurement sigma was determined to be less than that used for design, thus indicating that a sufficient number of samples was 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 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 required.
In addition, while not part of the release decision criteria, removable contamination sampling did not identify loose surface contamination above the MDA.
It is concluded that FB-3000, Survey Unit 1, met the release criteria of IOCFR20.1402 and the State of Maine enhanced criteria.
FB-3000-01, Revision 0 Page 6 of 19
J. REFERENCES
- 1. Maine Yankee Engineering Calculation, EC-039-01
- 3. Approach for Dealing with Background Radioactivity for Maine Yankee Final Status Surveys, Attachment E to Maine Yankee Procedure, FSS Data Processing and Reporting, PMP 6.7.8
- 4. Maine Yankee License Termination Plan, Revision 3, Maine Yankee letter to the NRC, MN-02-048, dated October 15, 2002
- 5. Maine Yankee Engineering Calculation, EC-009-01
- 6. Maine Yankee Engineering Calculation, EC-032-01 FB-3000-01, Revision 0 Page 7 of 19
Attachment 1 Survey Unit Maps FB-3000-01, Revision 0 Page 8 of 19
Mainnkee Decommission 1ng Team Maine MIneYne Yankee Decommissioning Project Survey Map I Map ID
- FB-3000-001 Survey Type OCher.eterlztfion OTurnover *EFnal Status Survey Dseckground Assessment , Survey Area Name: Sewage Treatment Plant Pit llWaste Treatment Building (Site Location)ll II I I tLff MP. O,El 1- ...
t)
Deomamssioikee Maine Yankee Decommissioning Project Survey Map I Survey Type: OCheraeterizetton OTurnover EFinas Status Survey OBselkground Assessment F Survey Area Name: Sewage Treatment Plant Pit t'Ar4 FB3000 Survey Unit 1 Direct Measurement Locations FB-3000-01, Revision 0 Page IO of 19
DcomamnssiYanike I Maine Yankee Decommissioning Project Survey Map I Map ID
- FB-3000 004 Survey Type: OCharseterlzstion OTurnover ETinat Status Survey O1ackground Assessment Survey Area Name: Sewage Treatment Plant Pit MN FB3000 Survey Unit 1 Scan Grid Locations Area around each of the 14 soaple point locations Is I meter by 1 meter. (14 suaore meters)
Areo around surriIs 1 meter up the wall. 1 meter from each (east/west) side edge of the sumfP. and two meters out from the wall. Scan area Includes walls and floor of sump .
(9.31 square mneters) FB-3000-1-COlS = Sump FB-3000-1-C016= Floor FB-3000-1-C017=Wall FB-3000-01, Revision 0 Page II of 19
Attachment 2 Survey Unit Instrumentation FB-3000-01, Revision 0 Page 12 of 19
TABLE 2-1 INSTRUMENT INFORMATION E-600 S/N I Probe S/N (type) 1643 1 148117 (43-68)
HPGe Detectors for Lab Analysis of Volumetric Samples I Detector Number I MDC (uCi/mL)
DET-3 I 1E-8 FSS-2 I - 1E-8 TABLE 2-2 INSTRUMENT SCAN MDC AND COMPARISION WITH DCGL AND INVESTIGATION LEVEL Detector 43-68 (Flat) I Comments Scan MDC 1832 LTP Table 5-6 (dpm/rl00 cm2 )
(dpmll00 cm 2 ) 18,000 Table 1 Investigation Level 1340 c/r Alarm Setpoint (8181) - 0.5 DCGL (dpm/100 cm 2 ) (8181)
FB-3000-01, Revision 0 Page 13 of 19
Attachment 3 Investigation Table (None Required)
FB-3000-01, Revision 0 Page 14 of 19
Attachment 4 Statistical Data FB-3000-01, Revision 0 Page 15 of 19
Survey Package FB-3000 Unit 1 Surface Sign Test Summary
- ,;- - ' - Evaiuatlonh nputVatues. .. 'JComments K' Survey Package: FB.3000 Sewage Treatment Plant Survey Unit: 01 Evaluator: GP DCGL,: 18,000 DCGL.: 18,000 LBGR: 9,000 Sigma: 1,052 Type I error: -- - 0.05 __
Type II error. 0.05 Total Instrument Efficiency: 13.0%
Detector Area (cm2): 126 Concrete Choosing 'N/A sets material Material Type: Unpainted background to "0" a j lV ae aues d- u,< acu '-i-CrmbnW'...-'
Z,: .- *1.645 ZI.p: ' 1.645 Sign p: 0.99865 Calculated Relative Shift: - ' 8.5 Relative Shift Used: : 3.0 Uses 3.0 if Relative Shift >3 N-Value: ' ,^-: 11i N-Value+20%: .. 14 z;
- iJd<.P'Static %. Data V aues., omm t Number of Samples: 14 Median: "-82 Mean: 114 Net Static Data Standard Deviation: :251 Total Standard Deviation: 3.---
07 Sum of samples and all background Maximum: 239
.. gnese yCK6rnment&- .Y -~
Adjusted N Value: 14 S+ Value: 14 Critical Value: 10
___ -________ri__ e .o rnm ent Sufficient samples collected: ' -Pass Maximum value <DCGL,: i' - Pass Median value <DCGL,: Pass Mean value <DCGLw: Pass Maximum value <DCGLemc: ,"!.--Pass Total Standard Deviation <=Sigma: Pass Sign test results: Pass
,;v'i.'2t's@-'i;tii%.{Fnal Status '-i menr>; ~'i ' t{
The survey unit passes all conditions:l;;: - 2'.' Pass FB-3000-SU1-SurfaceSign FB-3000-01, Revision 0 9129/04 1:38 PM Page 16 of 19
FB-3000 SU-1 Quantile Plot 400 200 E
-r 0
0 0 I I *
- I o0 w cC
- Activity (dpm/100 cm2) 00 c C 25 *50 75 1 E -200 C.)
O :x a.
- CD
- 0 -Median (dpm/100 cm2)
- Ia
-400 C.,
-600
-800 Percent
One-Sample T-Test Report Page/Date/Time 2 9/29/04 1:36:47 PM Database C:\Program Files\NCSS97\FB3000SUl.S0 Variable C2 Plots Section Histogram of FB-3000, SU-1 6.000 Cn C) 4.500 E
co .. '.'
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0 3.000
- i. 'a" a)
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= 1.500 j, .': '-:
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-800.000
. .A IA~. .
.500.000
-200.000 100.000 400:000 Activity (dpm/100 cm2)
FB-3000-01, Revision 0 Page 18 of 19
One-Sample T-Test Power Analysis Page/Date/Time 2 9/29/04 1:37:32 PM Chart Section Retrospective Power Curve
- 1.04 - - - -- --
0.8 ---- -----
a) l 0.6 - - - - - Il a L_
X - -I - -- -
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-5600 0 5d00 1o6oo 15600 20600 Survey Unit Mean (dpm/100 cm2)
FB-3000-01, Revision 0 Page 19 of 19