ML061000174
| ML061000174 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 04/07/2006 |
| From: | Cowan P Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TAC MC7519 | |
| Download: ML061000174 (7) | |
Text
Exelon Ruciear www.exe1oncorp corn zoo Exelon Way Kennetfiquare, PA 19348 10 CFR 50.90 April 7, 2006 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Peach Bottom Atomic Power Station, Unit 3 Renewed Facility Operating License No. DPR-56 NRC Docket No. 50-278
Subject:
Response to Request for Additional Information - License Amendment Request, "Proposed Changes to Extend the Use of Pressure-Temperature Limits Specified in Technical Specifications Figures 3.4.9-1, 3.4.9-2, and 3.4.9-3" (TAC No.
References:
(1) Letter from P. 6. Cowan, Exelon Generation Company, LLC, to U. S. Nuclear Regulatory Commission, License Amendment Request, "Proposed Changes to Extend the Use of Pressure-Temperature Limits Specified in Technical Specifications Figures 3.4.9-1, 3.4.9-2, and 3.4.9-3," dated July 6, 2005.
(2) Email from T. Valentine, U.S. Nuclear Regulatory Commission, to G. Stewart, Exelon Generation Company, LLC, "Draft Request for Additional lnformation Regarding Proposed Amendment Request for Proposed Pressure-Temperature Curves, Peach Bottom Atomic Power Station (PBAPS), Unit No.
3," dated March 8, 2006.
In Reference 1, Exelon Generation Company, LLC (Exelon), requested a change to Renewed Facility Operating License No. DPR-56 for Peach Bottom Atomic Power Station (PBAPS), Unit
- 3. The proposed change would allow for extension of the use of the current Pressure-Temperature (P-T) limit curves specified in Technical Specifications (TS) Figures 3.4.9-1,
3.4.9-2, and 3.4.9-3 to 32 effective full power years (EFPY).
In Reference 2, the NRC requested additional information concerning the PBAPS, Unit 3 License Amendment Request (LAR). A conference call was conducted on March 14,2006, between Exelon (G. Stewart, et al) and the NRC (T. Valentine, et al), to provide clarification on the request for additional information (RAI). The attachment to this letter restates the NRC questions, and provides Exelon's response to each question.
Response to Request for Additional lnformation PBAPS Unit 3 P-T Curve LAR Docket No. 50-278 April 7, 2006 Page 2 Exelon has concluded that the information provided in this response does not impact the conclusions of the: (1) Technical Analysis, (2) No Significant Hazards Consideration under the standards set forth in 10 CFR 50.92(c), or (3) Environmental Consideration as provided in the original submittal (Reference 1).
There are no regulatory commitments contained within this letter. If you have any questions or require additional information, please contact Glenn Stewart at 61 0-765-5529.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 7th day of April 2006.
Respectfully, Director - Licensing & Regulatory Affairs Exelon Generation Company, LLC
Attachment:
Response to Request for Additional lnformation cc:
Regional Administrator - NRC Region I NRC Senior Resident Inspector - PBAPS NRC Project Manager, NRR - PBAPS Director, Bureau of Radiation Protection - Pennsylvania Department of Environmental Protection w/ attachment I 1
Page 1 of 5 ATTACHMENT Peach Bottom Atomic Power Station, Unit 3 Docket No. 50-278 Proposed Changes To Extend the Use of Pressure-Temperature Limits Specified in Technical Specifications Figures 3.4.9-1, 3.4.9-2, And 3.4.9-3 Response to Request for Additional Information In Reference 1, Exelon Generation Company, LLC (Exelon), requested a change to Renewed Facility Operating License No. DPR-56 for Peach Bottom Atomic Power Station (PBAPS), Unit
- 3. The proposed change would allow for extension of the use of the current Pressure-Temperature (P-T) limit curves specified in Technical Specifications (TS) Figures 3.4.9-1, 3.4.9-2, and 3.4.9-3 to 32 effective full power years (EFPY).
In Reference 2, the NRC requested additional information concerning the PBAPS, Unit 3 License Amendment Request (LAR). A conference call was conducted on March 14, 2006, between Exelon (G. Stewart, et al) and the NRC (T. Valentine, et al), to provide clarification on the request for additional information (RAI). This attachment restates the NRC questions, and provides Exelon's response to each question.
Question 1.
In order to evaluate the neutron flux distribution that would bound the licensed power conditions for the PBAPS reactors, the operating condition assumed for the flux calculation was based on the projected Limerick Generating Station (LGS), Unit 2, Cycle 6 core data. Please explain why it is appropriate to use LGS, Unit 2, Cycle 6 core information to calculate fast neutron flux for the PBAPS, Unit 3 core. Please include the following information:
(a)
Describe the similarities (fuel, geometry, power distribution, etc.) between LGS and PBAPS, Unit 3 that allows to use the analogy.
Response
The in-vessel components that have significant impacts on vessel flux distribution are very similar for PBAPS, Unit 3, and LGS, Unit 2. For instance the following parameters are identical between these two units:
Vessel inside diameter (design value)
Core shroud inside diameter and thickness Size and azimuthal locations of jet pump mixers and risers Azimuthal location of surveillance capsules, all shadowed by jet pump riser Number of fuel bundles (764) and bundle layout The core loading for a representative cycle (Cycle 12) of PBAPS, Unit 3, consists of mostly General Electric (GE) 9x9 fuel (GE11 and GE13). Similarly, LGS, Unit 2, Cycle 6 core loading consists of mostly GE 9x9 fuel (GE13 and GE11). Therefore, the loaded fuel is similar.
Response to Request for Additional Information Attachment PBAPS Unit 3 P-T Curve LAR Page 2 of 5 Docket No. 50-278 In general, the peak vessel flux is influenced by a small number of fuel bundles in the core periphery that are closest to the peak flux location. For fluence accumulated in one cycle, the cycle energy generation in these important bundles determines the peak vessel fluence.
Figures 1-1 and 1-2 show the relative cycle energy data for LGS, Unit 2, Cycle 6 and PBAPS, Unit 3, Cycle 12, respectively. The neutron flux calculation performed for LGS, Unit 2, Cycle 6 shows that the peak vessel flux is at 26° azimuth (and octant symmetry location of 64°). Thus, the most important bundle for the peak vessel flux is the closest bundle, which is identified as (I=22, J=1) in Figure 1-1. Comparison of cycle energy for the peak bundle and neighboring bundles clearly shows that PBAPS, Unit 3, Cycle 12 has significantly lower cycle energy for these important bundles than the corresponding LGS, Unit 2, Cycle 6 bundles. It is, therefore, concluded that vessel flux for PBAPS, Unit 3 is bounded by LGS, Unit 2, Cycle 6.
(b)
When was the PBAPS, Unit 3 dosimetry removed and measured; was it behind the jet pump riser; and if it was behind the jet pump riser, how was it calculated and which code (and cross sections) were used for its analyses?
Response
The PBAPS, Unit 3 capsule was removed in 1987 at the end of Cycle 7. This capsule was located at 30-degree azimuth, behind the jet pump riser. The full power flux and fluence were determined from the power history from plant operating data applicable to period of residence of the dosimetry capsule in the reactor, measured count rate of each dosimeter, and effective activation cross sections for each dosimeter. The effective activation cross sections were obtained from measured cross sections determined at GEs Vallecitos Nuclear Center from more than 65 spectral determinations for Boiling Water Reactors (BWRs) and for the GE Test Reactor using activation monitors and spectral unfolding techniques. These cross sections are applied to BWR pressure vessel locations based on water gap from fuel to vessel wall. Detailed discussions can be found in Section 6 of GEs Licensing Topical Report NEDC-32983P-A, General Electric Methodology for Reactor Pressure Vessel Fast Neutron Flux Evaluations, as approved by the NRC (Reference 3).
Question 2.
The license amendment request states that a bounding calculation of reactor vessel 32 EFPY fast neutron fluence was completed for PBAPS, Unit 3, using the NRC approved methodology (Reference 3), which adheres to the guidance in Regulatory Guide 1.190.
Please provide the following information used to perform the analysis:
(a)
Describe the angular decomposition of the scattering cross-section that was employed in the analysis.
Response
P3 truncation of the Legendre polynomial expansion of the scattering cross sections was used in the neutron transport calculation.
Response to Request for Additional Information Attachment PBAPS Unit 3 P-T Curve LAR Page 3 of 5 Docket No. 50-278 (b)
Describe the spatial representation that was employed in the discrete ordinates calculations.
Response
An S12 fully symmetric angular quadrature set was used in the neutron transport calculation.
References:
(1)
Letter from P. B. Cowan, Exelon Generation Company, LLC, to U. S. Nuclear Regulatory Commission, License Amendment Request, "Proposed Changes to Extend the Use of Pressure-Temperature Limits Specified in Technical Specifications Figures 3.4.9-1, 3.4.9-2, and 3.4.9-3," dated July 6, 2005.
(2)
Email from T. Valentine, U.S. Nuclear Regulatory Commission, to G. Stewart, Exelon Generation Company, LLC, Draft Request for Additional Information Regarding Proposed Amendment Request for Proposed Pressure-Temperature Curves, Peach Bottom Atomic Power Station (PBAPS), Unit No. 3," dated March 8, 2006.
(3)
Letter from S. A. Richards, U.S. NRC, to J. F. Klapproth, GE Nuclear Energy, Safety Evaluation for NEDC-32983P, General Electric Methodology for Reactor Pressure Vessel Fast Neutron Flux Evaluation (TAC No. MA9891), dated September 14, 2001.
Response to Request for Additional Information Attachment PBAPS Unit 3 P-T Curve LAR Page 4 of 5 Docket No. 50-278 Figure 1-1 Relative Cycle Energy by Bundle - Limerick 2, Cycle 6 I=
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 J=
1 0.473 0.471 0.463 0.529 0.511 0.439 0.391 2
0.783 0.774 0.783 0.814 0.758 0.697 0.623 0.473 3
0.901 0.761 0.930 0.920 0.724 0.835 0.776 0.739 0.589 0.390 4
1.186 1.064 1.190 1.046 1.155 0.959 0.743 0.862 0.796 0.624 5
1.100 1.281 0.878 1.276 1.081 1.237 1.013 1.133 0.911 0.826 0.645 6
1.312 1.176 1.342 1.177 1.320 1.118 1.270 1.041 1.133 1.068 0.825 0.624 0.391 7
0.846 1.330 1.172 1.348 0.916 1.334 1.116 1.199 0.807 1.133 0.911 0.797 0.590 8
1.243 1.150 1.375 1.208 1.345 1.170 1.339 1.073 1.199 1.041 1.134 0.864 0.739 0.474 9
0.868 1.321 1.164 1.337 1.174 1.336 1.169 1.341 1.118 1.271 1.014 0.744 0.776 0.625 0.393 10 1.268 1.128 1.298 0.935 1.244 0.765 1.336 1.172 1.336 1.119 1.238 0.960 0.836 0.711 0.441 11 0.868 1.265 0.868 1.172 0.840 1.244 1.174 1.345 0.916 1.321 1.081 1.156 0.725 0.761 0.513 12 1.213 1.127 1.279 1.037 1.172 0.935 1.336 1.207 1.349 1.177 1.277 1.047 0.920 0.814 0.529 13 0.941 1.302 1.120 1.280 0.869 1.298 1.167 1.377 1.172 1.341 0.878 1.190 0.931 0.784 0.464 14 1.272 1.121 1.302 1.126 1.266 1.128 1.322 1.150 1.332 1.177 1.282 1.066 0.761 0.774 0.470 15 0.904 1.272 0.941 1.214 0.869 1.269 0.869 1.246 0.847 1.313 1.099 1.187 0.901 0.783 0.473
Response to Request for Additional Information Attachment PBAPS Unit 3 P-T Curve LAR Page 5 of 5 Docket No. 50-278 Figure 1-2 Relative Cycle Energy by Bundle - Peach Bottom 3, Cycle 12 I=
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 J=
1 0.433 0.424 0.410 0.388 0.367 0.333 0.272 2
0.869 0.887 0.844 0.796 0.764 0.726 0.625 0.344 3
1.189 1.175 1.127 0.965 1.075 0.908 0.908 0.529 0.368 0.221 4
1.107 1.259 0.871 1.220 1.050 1.186 0.950 0.854 0.687 0.386 5
1.315 1.136 1.290 1.143 1.315 1.289 1.191 0.974 0.722 0.685 0.429 6
0.946 1.305 1.155 1.334 1.153 1.312 0.884 1.154 0.918 0.865 0.685 0.385 0.220 7
1.264 1.151 1.338 0.965 1.316 1.167 1.284 1.057 0.822 0.917 0.721 0.687 0.367 8
1.077 1.301 1.159 1.311 1.144 1.331 1.143 1.265 1.057 1.153 0.972 0.853 0.526 0.343 9
1.250 0.926 1.250 1.156 1.331 0.974 1.283 1.142 1.285 0.883 1.189 0.949 0.907 0.624 0.272 10 0.860 1.199 1.072 1.299 1.145 1.286 0.974 1.330 1.167 1.312 1.289 1.186 0.908 0.725 0.333 11 1.222 1.115 1.284 0.924 1.242 1.145 1.331 1.144 1.314 1.153 1.313 1.049 1.077 0.765 0.370 12 0.933 1.295 1.130 1.237 0.924 1.297 1.155 1.310 0.964 1.334 1.142 1.221 0.965 0.798 0.392 13 1.288 1.109 1.290 1.130 1.283 1.073 1.250 1.158 1.339 1.155 1.288 0.870 1.129 0.846 0.409 14 1.097 1.270 1.109 1.293 1.116 1.199 0.925 1.301 1.151 1.306 1.136 1.258 1.175 0.887 0.424 15 0.892 1.098 1.289 0.935 1.224 0.860 1.246 1.077 1.264 0.945 1.314 1.107 1.188 0.868 0.427