ML042710479
| ML042710479 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 09/14/2004 |
| From: | Vanags U Maine Yankee Atomic Power Co |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| FA-0600 | |
| Download: ML042710479 (24) | |
Text
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FA-0600 PRIMARY AUXILARY BUILDING SURVEY UNIT 9 Prepared By': .46flaf56ate: //-
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Signature edName Approved By: high Date:
PrSSntenden Printed Name/ignature Revision 0
MAINE YANKEE FINAL STATUS SURVEY RELEASE RECORD FA-0600 PRIMARY AUXILARY BUILDING SURVEY UNIT 9 A. SURVEY UNIT DESCRIPTION FA0600 is the survey area that consists of the basement level of the Primary Auxiliary Building (PAB) at coordinates 407650N & 623850E using the Maine State Coordinate System (West Zone) NAD 1927, as shown on Map ID# FA0600-SITE in Attachment 1.
The PAB contained the liquid and gaseous storage and cleanup systems for reactor operations.
The basement construction was reinforced concrete floors and walls, and was located entirely within the Restricted Area (RA). During plant operation, most cubicles in the basement of the PAB were posted as radiation areas, and operational surveys confirmed the presence of contamination.
Survey Unit 9 is located in Survey Area FA0600, the Primary Auxiliary Building (PAB), and consists of the floor and lower walls of the Aerated Drain Tank and Pump Cubicle in the eleven foot elevation of the PAB. The area is located within the radiologically Restricted Area north of the Containment Building and adjacent to the Fuel Building. The unit consists of interior concrete walls, floor, penetrations and equipment pedestal remnants from the 17 foot elevation to the 11 foot elevation. Floor trenches in this survey unit were not included; these are included in FA0600 Survey Unit 12. Penetrations between Survey Unit 9 and adjoining Survey Units 5 and 6 were not included in Survey Unit 9; these were included in Survey Unit 5 and 6, respectively.
The area of Survey Unit 9 is approximately 136 m2 .
B. SURVEY UNIT DESIGN INFORMATION Based on the site historical information, as confirmed by site characterization, the area was designated a Class 1 survey unit per the LTP. Survey Unit 9 of FA0600 is shown on the maps in Attachment 1.
The survey unit design parameters are shown in Table 1. Given a relative shift of 2.3, it was determined that 15 direct measurements were required for the Sign Test. Measurement locations were generated using a random start, fixed-grid and are shown on map FA0600-09C (Attachment 1). Once the direct measurements were completed, removable surface contamination samples were obtained at each measurement location.
A 100% scan coverage of the area was required, and was accomplished by dividing the area into 188 scan grids each of approximately 1 m area . Scan grids are shown on maps FA 0600-09, 09A, 09B, and 09E (Attachment 1). Instrument scan setpoints were conservatively set below the DCGLENMC, as shown in Table 2-2 (Attachment 2).
Some scan grids were smaller than I m2.
FA-0600-9, Revision 0 Page 2 of 24
To accommodate measurement geometry requirements for surfaces of non-uniform smoothness, the SHP-360 probe was used to augment the 43-68 scan survey. First, a 43-68 detector scan was performed on all surfaces, including those that were unlikely to meet geometry requirements for that model of probe. Then a repeat scan, using the SHP-360, was performed on areas with surface irregularities that required a smaller probe size. The SHP-360 was also used to scan concrete and steel penetrations. Ninety-degree surface junctures (i.e., wall-floor and wall-wall) were scanned using the 43-68 probe with a reduced efficiency.
Background values were established, for each particular instrument probe application based on ambient background values in the survey area, previously established material backgrounds, and/or ambient background. These background values, listed in Table 1, were used to establish net activity for direct measurements, scan alarm set-points, and to confirm the scan MDCs used were appropriate.
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, the investigation level, and the DCGLEMC. 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 were consistent with design backgrounds used to determine the instrument scan MDC values (listed in LTP Table 5-6). Further, since the investigation level at the alarm setpoint was always less than the design DCGLErIC, no EMC sample size adjustment was necessary.
FA-0600-9, Revision 0 Page 3 of 24
TABLE 1 SURVEY UNIT DESIGN PARAMETERS: FA-0600-9 SURVEY UNIT 9 l DESIGN CRITERIA l BASIS Area 136 N/A Number of Direct Measurements Required 15 Based on an LBGR of 9000 dpm/100 cm 2 ,
sigma 2 of 3811 dpmi/100 cm 2 , a relative shift of 2.3.
Type I=Type II=0.05.
Sample Area 9.0 m' 136 m'/15 samples = 9.0 m2 Sample Grid Spacing 3.0 mr Scan Grid Area 1 mx 1 m Class 1 Structure Area Factor 5.5 50 m'/9.0 m' per LTP, Rev.3 3 Scan Survey Area 136 m' 100% for Class I Survey Unit Background P11 43-68 Direct and Scan (flat surfaces) 3,101 dpm/lO0 cm Ambient and Material 43-68 Scans (Junctures) 6,263 dpm/l00 cm' Ambient and Material SHP-360 Scans (Penetrations - Steel) 2,295 dpm/I 00 cm' Ambient SHP-360 Scans (Penetrations - Concrete) 16,447 dpm/lO0 cm2 Ambient and Material SHP-360 Scans (Surfaces Irregularities) 9,320 dpm/100 cm' Ambient and Material Scan Investigation Level See Table 2-2 See Table 2-2
_ (Attachment 2)
DCGL 18,000 dpm/I00 cm' Based on Rev. 3 of the
_ LTP.
Design DCGLemc 99,000 dpm/lO0 cm' Class 1 area, AF=5.5 based on basement contamination model (LTP Rev 3 section 6.8.1).
2 Basis for sigma from PAB-EI. I Ift A0600, LTP Table 5-lA 3 " LTP, Rev. 3" refers to the LTP submitted in October 2002 (Reference 1) as amended by the MY's addenda of November 2002 (Reference 2). LTP, Rev. 3 was approved by the NRC in February 2003 (Reference 3).
FA-0600-9, Revision 0 Page 4 of 24
C. SURVEY RESULTS Fifteen direct measurements were made in Survey Unit 9. All of the direct measurements were below the DCGL. The direct measurement data are presented in Table 2.
There were no alarms received during scan surveys; therefore no investigations were required.
D. SURVEY UNIT INVESTIGATIONS PERFORMED AND RESULTS None required.
TABLE 2 DIRECT CONCRETE MEASUREMENTS: FA-0600 SURVEY UNIT 9 Sample Location Gross Activity Net Activity (Table 1 Background Subtracted) dpm/100 cm dpm/100 cm2 FA060091COOlBDOOOO 4188 1087 FA060091C002BDOOOO 3773 672 FA060091C003BDOOOO 3968 867 FA060091C004BDOOOO 3974 873 FA060091C005BDOOOO 4212 1111 FA060091CO06BDOOOO 3895 794 FA060091C007BDOOOO 3791 690 FA060091CO08BDOOOO 4359 1258 FA060091C009BDOOOO 4139 1038 FA060091COIOBDOOOO 3529 427 FA060091COIIBDOOOO 3498 397 FA060091CO12BDOOOO 3278 177 FA060091CO13BDOOOO 2985 -116 FA060091CO14BDOOOO 3419 317 FA060091CO15BDOOOO 3327 226 Average 3756 655 Median 3791 690 Standard Deviation 401 401 Range 2985 - 4359 -116 - 1258 FA-0600-9, Revision 0 Page 5 of 24
E. SURVEY UNIT DATA ASSESSMENT RESULTS An analysis of the direct sample measurement results, including the mean, median, standard deviation, and sample result range, are provided in Table 2. All of the 15 direct concrete measurements were below the DCGL value of 18,000 dpm/100 cm 2 . The maximum direct sample result, not corrected for background, was equivalent to 4359 dpmIO00 cm 2 .
When adjusted for background, the mean residual contamination level is 655 dpm/100 cm 2 .
This would be equivalent to an annual dose of 0.011 mrem. 4 F. ADDITIONAL DATA EVALUATION Attachment 4 provides additional data evaluation associated with Survey Unit 9, 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 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 and indicates general symmetry about the median. The data set and plot are consistent with expectations for a Class 1 survey unit. The maximum net activity (1258 dpm/100 cm2 at location C008) is well below the DCGL of 18,000 dpm/1 00 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.
- 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 ("powver") 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., < 3.2 dpm/l 00 cm 2 ) and beta activity less than the MDA values (i.e., < 4.0 dpm/rl00 cm 2 ). 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.
4 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.
FA-0600-9, Revision 0 Page 6 of 24
G. CHANGES IN INITIAL SURVEY UNIT ASSUMPTIONS ON EXTENT OF RESIDUAL ACTIVITY The survey was designed as a Class 1 area; the FSS results were consistent with that classification. The survey sample standard deviation was less than the design sigma. Thus, a sufficient number of sample measurements were taken.
H. LTP CHANGES SUBSEQUENT TO SURVEY UNIT FSS The FSS of Survey Unit 9 was designed and performed using the criteria of the approved LTP (Revision 3 Addenda). The only subsequent LTP changes (with potential impact to this FSS) were provided in the proposed license amendment related to modifications of the activated concrete remediation plan submitted September 11, 2003 (Reference 4). Changes represented in this later proposed license amendment have been evaluated and have no impact on the design, conduct, or assessment of the final status survey of Survey Unit 9.
I. CONCLUSION The FSS of this survey unit was designed based on the LTP designation as a Class 1 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 2
direct measurements were less than the DCGL of 18,000 dpm/1 00 cm .
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 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 1 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 confirmed that the majority of remaining activity in this basement survey unit was fixed.
It is concluded that FA0600 Survey Unit 9 meets the release criteria of 10CFR20.1402 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 FA-0600-9, Revision 0 Page 7 of 24
Attachment 1 Survey Unit Maps FA-0600-9, Revision 0 Page 8 of 24
Maine Yankee Map ID#:FA0600-SITE Decommissioning Team MAaine Yankee DecommissioningProjectSurvey Form I Survey Type: L Characterization El Turnover
- Final Status Survey PAB 623,000 E 623.500 E 624,000 E 624,500 E 625,000 E l FAO600 MN 0 400 800 1200 N FA-0600-9, Revision 0 Page 9 of 24
Maine YankeeTeam Decommissioning mMaine Yankee Decommissioning Project Survey Form Map ID #: FA0600 GA Tam Survey Type: Characterization O nTurnover *Final Status Survey I Survey Area Name: PAB Gene ral Area PAB 11'
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Page 10 of 24
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Note: Grid C167 does not exist,surveyed as part of Survey Unit 12.
Maine YankeeMaID#F00-9 Decommissioning Team Maine Yankee Decommissioning Project Survey Form Map ID#:FA0600-09A Survey Type: El Characterization El Turnover
- Final Status Survey Survey Area Name: Aerated Drain Tank Cubicle IFloor Juncture FA0600 SU9 Floor Junctures C177 IF1 C186 II II I 85 C178 FA-0600-9, Revision 0 Page 12 of 24
Decommissioning Teamnl Maine Yankee Decommissioning Project Survey Form Map ID#:FA0600-09B Survey Type: El Characterization O Turnover
- Final Status Survey I Survey Area Name: Aerated Drain Tank Cubicle Wall Juncture FA0600 SU9 Wall Junctures I- 2 ii 191_1y92 IzzI =Wall Juncture FA-0600-9, Revision 0 Page 13 of 24
D M ion.ne Decommissioning Team I Maine Yankee Decommissioning Project Survey Form Map ID#: FAo600-09C I
Survey Type: O Characterization LI Turnover
- Final Status Survey survey Area Name: Aerated Drain Tank Cubicle S
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Maine Yankee Map ID #:FA0600-09E Decommissioning Team Maine Yankee Decommissioning Project Survey Form Survey Type: CI Remediation L Turnover IN Final Status Survey lSurveyArea Name: PENETRATIONS FAO600 SU0O9 PEN ETRATIONS FA-0600-9, Revision 0 Page 15 of 24
Attachment 2 Survey Unit Instrumentation FA-0600-9, Revision 0 Page 16 of 24
TABLE 2-1 INSTRUMENT INFORMATION E-600 S/N Probe S/N (type) 1622 148937 (43-68) 1929 149071 (43-68) 1622 149071 (43-68) 2489 149074 (43-68) 2489 149075 (43-68) 1929 453 (SHP-360) 2489 451 (SHP-360) 1622 454 (SHP-360) 2491 463 (SHP-360) 2491 451 SHP-360) 1619 149069 (43-68) 1619 454 (SHP-360)
FA-0600-9, Revision 0 Page 17 of 24
TABLE 2-2 INSTRUMENT SCAN MDC AND COMPARISON WITH DCGL, AND DESIGN DCGLEMC Detector 43-68 43-68 SBP-360 SIP-360 SLP-360 Flat Junctures Penetrations Penetrations Surface (Steel) (Concrete) Irregularities Scan MDC 1,832 4,330 4,876 18,501 10,484 (dpm/100 cm) LTP Table 5-6 (Note 1) (Note 3) (Note 4) LTP Table 5-6 DCGL 18,000 18,000 18,000 18,000 18,000 (dpm/100 cm 2 )
Investigation 21,062 24,242 40,800 94,621 63,596 Level (Alarm setpoint) (-DCGL + (-DCGL + (Note 2) (Note 2) (Note 2)
(dpm/100 cm 2) Background) Background)
(Note 5) (Note 5)
Design 99,000 99,000 99,000 99,000 99,000 DCGLEMC (dpm/100 cm 2 )
(from Release Record Table 1)
Notes:
- 1. Separate scan MDC developed for the 43-68 when applied to juncture geometry (as determined and documented in site calculation).
- 2. The specific alarm setpoints were established below the design DCGLENIc of 99,000 dpmn/lOOcm 2 .
- 3. MDC Scan for SHP-360 from LTP Rev 3 was adjusted to account to account for pipe curvature and bare metal efficiency.
- 4. MDC Scan for SHP-360 on concrete penetrations is estimated from the LTP SHP-360 adjusted for penetration curvature.
- 5. Alarm setpoints were typically rounded to the nearest 5 c/m.
FA-0600-9, Revision 0 Page 18 of 24
Attachment 3 Investigation Table (No Investigations were required in SU-9)
FA-0600-9, Revision 0 Page 19 of 24
Attachment 4 Statistical Data FA-0600-9, Revision 0 Page 20 of 24
Survey Package FA-0600 Unit 9 Surface Sign Test Summary
.--. alnution Inpist Vhis... K . Commen -
Survey Package: FA-0600 Primary Auxiliary Building Survey Unit: 09 Evaluator: GP DCGL,,: 18,000 DCGLemc: 99,000 LBGR: 9,000 Sigma: 3,811 Type I error: : 0.05 Type II error: 0.05 Total Instrument Efficiency: 13.0%
Detector Area (cm)): 126 Concrete Choosing 'NIX sets material Material Type: Unpainted background to "0" anld
.. cICUlaed :ge __A=_ _ __Hi Z1, t: 1.645 Zi-0: -1.645 Sign p: 0.97725 Calculated Relative Shift: 2.3 Relative Shift Used: ; 2.3 Uses 3.0 if Relative Shift >3 N-Value: ; :12 N-Value+20%:.. ; i- ti--: - 15 x'>' 'od < 4',f~tr'Sa ~u~
t ic' Xa t L _ _ _ _ _ _ _ _ _ _ _ _
Number of Samples: . 15 Median: :.685 Mean: 649 Net Static Data Standard Deviation: 401 Total Standard Deviation: *: . -i 439 SRSS Maximum: 7 . 1,252 Adjusted N Value: - 15 S+ Value: . 15 Critical Value: 11
. I .s .K . CrIterISao Sufficient samples collected: Pass Maximum value <DCGLw: Pass Median value <DCGL,: "Pass Mean value <DCGL: . - Pass Maximum value <DCGLemc: - . Pass Total Standard Deviation <=Sigma: x Pass Sign test results: -- Pass al S . .. - . Commen'ts The survey unit passes all conditions: l Pass FA-0600-SU9-SurfaceSign 7/13104 11:50AM FA-0600-9, Revision 0 Page 21 of 24
One-Sample T-Test Report Page/Date/Time 2 7/13/04 11:53:42 AM Database C:\Program Files\NCSS97\FA0600SU9.SO Variable C2 Plots Section Histogram of FA-0600, SU-9 FA-0600-9, Revision 0 Page 22 of 24
One-Sample T-Test Power Analysis Page/Date/Time 2 7113/04 11:5426 AM Chart Section Retrospective Power Curve 1.0 - _ _ _ _ _ _ _ _ _ _ _ _ _ _
I I 0.8 0.6 - - - - - - - - - - .-- - - -
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II XI I l\ - - - -
Survey Unit Mean FA-0600-9, Revision 0 Page 23 of 24
FA-0600 SU-9 Quantile Plot 1400 1200 (I
E 1000 u
800 . .
- Activity (dpm/100 cm2) Cl CT Q
0 I E 600 CN la -Median (dpm/100 400 cm2)
.W-u 200 0 I I- _
-200
- 25 50 75 1 Percent