ML110700146
| ML110700146 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  (DPR-044, DPR-056) |
| Issue date: | 03/10/2011 |
| From: | David Helker Exelon Nuclear, Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TAC ME5392, TAC ME5393 | |
| Download: ML110700146 (3) | |
Text
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it I WI Fl, PA 1Q 34 10 CFR 50.55a March 10, 2011 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Peach Bottom Atomic Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-56 NRC Docket Nos. 50-277 and 50-278
Subject:
Additional Information Associated with the Acceptance Review of Relief Request Concerning Reactor Pressure Vessel Circumferential Shell Welds
References:
1)
Letter from D. P. Helker (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, Proposed Relief Request associated with the Requirements of 10 CFR 50.55a Concerning Reactor Pressure Vessel Circumferential Shell Welds, dated January 24, 2011 2)
Letter from J. D. Hughey (U.S. Nuclear Regulatory Commission) to M. J.
Pacilio (Exelon Generation Company, LLC), Peach Bottom Atomic Power Station, Units 2 and 3: Supplemental Information Needed for Acceptance of Requested Licensing Action RE: Relief Request 14R-51 (TAC NOS. ME5392 and ME5393), dated February 28, 2011 In the Reference 1 letter, Exelon Generation Company, LLC (Exelon) submitted for your review and approval a proposed alternative in accordance with 10 CFR 50.55a(a)(3)(i) concerning reactor pressure vessel circumferential shell welds. In the Reference 2 letter, the U.S. Nuclear Regulatory Commission requested additional information as part of the acceptance review.
Attached is our response to this request.
There are no regulatory commitments contained in this letter.
If you have any questions or require additional information, please contact Tom Loomis (610-765-5510).
Respectfully, David P. Helker Manager
- Licensing & Regulatory Affairs Exelon Generation Company, LLC
Attachment:
Response to Request for Additional Information cc:
USNRC Region I, Regional Administrator USNRC Senior Resident Inspector, PBAPS USNRC Project Manager, PBAPS R. R. Janati, Bureau of Radiation Protection S. T. Gray, State of Maryland 10 CFR 50.55a March 10, 2011 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Peach Bottom Atomic Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-56 NRC Docket Nos. 50-277 and 50-278
Subject:
Additional Information Associated with the Acceptance Review of Relief Request Concerning Reactor Pressure Vessel Circumferential Shell Welds
References:
1)
Letter from D. P. Helker (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, IIProposed Relief Request associated with the Requirements of 10 CFR 50.55a Concerning Reactor Pressure Vessel Circumferential Shell Welds,1I dated January 24,2011 2)
Letter from J. D. Hughey (U.S. Nuclear Regulatory Commission) to M. J.
Pacilio (Exelon Generation Company, LLC), IIPeach Bottom Atomic Power Station, Units 2 and 3: Supplemental Information Needed for Acceptance of Requested Licensing Action RE: Relief Request 14R-51 (TAC NOS. ME5392 and ME5393),1I dated February 28,2011 In the Reference 1 letter, Exelon Generation Company, LLC (Exelon) submitted for your review and approval a proposed alternative in accordance with 10 CFR 50.55a(a)(3)(i) concerning reactor pressure vessel circumferential shell welds. In the Reference 2 letter, the U.S. Nuclear Regulatory Commission requested additional information as part of the acceptance review.
Attached is our response to this request.
There are no regulatory commitments contained in this letter.
If you have any questions or require additional information, please contact Tom Loomis (610-765-5510).
Respectfully, ffL 1f~
David P. Helker Manager - Licensing & Regulatory Affairs Exelon Generation Company, LLC
Attachment:
Response to Request for Additional Information cc:
USNRC Region I, Regional Administrator USNRC Senior Resident Inspector, PBAPS USNRC Project Manager, PBAPS R. R. Janati, Bureau of Radiation Protection S. T. Gray, State of Maryland
ATTACHMENT Response to Request for Additional Information Relief Request for Circumferential Shell Welds ATTACHMENT Response to Request for Additional Information Relief Request for Circumferential Shell Welds
Response RAI Relief Request Attachment for Circumferential Shell Welds March 10, 2011 Page 1 of 1 Request:
In order to accept the relief request for detailed NRC staff review, the staff requires that the licensee confirm that the fluence values contained in its submittal letter were calculated in a manner consistent with RG 1.190 or some other acceptable manner...
If the fluence values were not calculated using NEDC-32983P-A, Revision 2, then the NRC staff would also request that the licensee describe the fluence calculation method that was used and provide information concerning the qualification of the method for use on the BWR/4 vessel geometry in sufficient detail to determine whether the calculations were adherent to RG 1.190 guidance or some other acceptable methodology.
Resrjonse:
The information provided in the relief request is the current licensing basis information as documented in the Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3 Updated Final Safety Analysis Report, Appendix Q. However, more recent fluence values have been calculated in accordance with Regulatory Guide 1.190, Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence, dated March 2001. These fluence values were calculated utilizing the methodology contained in NEDC-32983P-A, General Electric Methodology for Reactor Pressure Vessel Fast Neutron Flux Evaluations, DRF 0000-001 2-4185, Revision 2, dated January 2006. These fluence values are less than those documented in Peach Bottoms current licensing basis discussed above, and are therefore bounded. The following are the results of the 54 EFPY fluence values for PBAPS, Units 2 and 3 as well as the computation of the associated mean RTNDT values for the limiting PBAPS circumferential shell welds:
Parameter PBAPS, Unit 2 PBAPS, Unit 3 Cu%
[1]
0.058 0.104 Ni%
[1]
0.949 0.938 CF 79.2 139.3 Fluence at clad/weld interface (n/cm 2
)
1.23 x 1018 9.54 x 1017 RTNDT (°F)
-32
-50 ARTNDTw/o margin (°F) 36.4 56.8 Mean RTNDT (°F) 4.4
6.8 Notes
1.
Best estimate chemistry values from BWRVIP-135, Revision 1 were used for conservatism.
Response RAI - Relief Request for Circumferential Shell Welds Request:
Attachment March 10, 2011 Page 1 of 1 In order to accept the relief request for detailed NRC staff review, the staff requires that the licensee confirm that the fluence values contained in its submittal letter were calculated in a manner consistent with RG 1.190 or some other acceptable manner... If the fluence values were not calculated using NEDC-32983P-A, Revision 2, then the NRC staff would also request that the licensee describe the fluence calculation method that was used and provide information concerning the qualification of the method for use on the BWR/4 vessel geometry in sufficient detail to determine whether the calculations were adherent to RG 1.190 guidance or some other acceptable methodology.
Response
The information provided in the relief request is the current licensing basis information as documented in the Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3 Updated Final Safety Analysis Report, Appendix Q. However, more recent fluence values have been calculated in accordance with Regulatory Guide 1.190, "Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence, II dated March 2001. These fluence values were calculated utilizing the methodology contained in NEDC-32983P-A, "General Electric Methodology for Reactor Pressure Vessel Fast Neutron Flux Evaluations, II DRF 0000-0012-4185, Revision 2, dated January 2006. These fluence values are less than those documented in Peach Bottom's current licensing basis discussed above, and are therefore bounded. The following are the results of the 54 EFPY fluence values for PBAPS, Units 2 and 3 as well as the computation of the associated mean RTNOT values for the limiting PBAPS circumferential shell welds:
Parameter PBAPS, Unit 2 PBAPS, Unit 3 Cu%
l1]
0.058 0.104 Ni%
llJ 0.949 0.938 CF 79.2 139.3 Fluence at clad/weld interface (n/cm 2
)
1.23 x 10'~
9.54 X 10' {
RTNOT (OF)
-32
-50
~RTNOT w/o margin (OF) 36.4 56.8 Mean RTNOT (OF) 4.4
6.8 Notes
1.
Best estimate chemistry values from BWRVIP-135, Revision 1 were used for conservatism.