ML12117A190
| ML12117A190 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 04/25/2012 |
| From: | Office of Nuclear Reactor Regulation |
| To: | Division of License Renewal |
| References | |
| Download: ML12117A190 (7) | |
Text
Davis-BesseNPEm Resource From: CuadradoDeJesus, Samuel Sent: Wednesday, April 25, 2012 2:06 PM To: dorts@firstenergycorp.com Cc: custerc@firstenergycorp.com; Harris, Brian; Davis-BesseHearingFile Resource
Subject:
Davis Besse Teleconference Attachments: Davis-Besse SER - RAI for USE and P-T curves - April-2012.docx Topic: To discuss USE and P-T limit curves draft RAIs (attached)
Date: Thursday, April 26, 2012 Time: 2:30pm to 3:30pm Phone: 888-324-2611 Participant passcode: 57046
- Regards, Samuel Cuadrado de Jesús Project Manager Projects Branch 1 Division of License Renewal U.S. Nuclear Regulatory Commission Phone: 301-415-2946 Samuel.CuadradoDeJesus@nrc.gov 1
Hearing Identifier: Davis_BesseLicenseRenewal_Saf_NonPublic Email Number: 3834 Mail Envelope Properties (377CB97DD54F0F4FAAC7E9FD88BCA6D092E8E50C71)
Subject:
Davis Besse Teleconference Sent Date: 4/25/2012 2:05:52 PM Received Date: 4/25/2012 2:05:56 PM From: CuadradoDeJesus, Samuel Created By: Samuel.CuadradoDeJesus@nrc.gov Recipients:
"custerc@firstenergycorp.com" <custerc@firstenergycorp.com>
Tracking Status: None "Harris, Brian" <Brian.Harris2@nrc.gov>
Tracking Status: None "Davis-BesseHearingFile Resource" <Davis-BesseHearingFile.Resource@nrc.gov>
Tracking Status: None "dorts@firstenergycorp.com" <dorts@firstenergycorp.com>
Tracking Status: None Post Office: HQCLSTR01.nrc.gov Files Size Date & Time MESSAGE 451 4/25/2012 2:05:56 PM Davis-Besse SER - RAI for USE and P-T curves - April-2012.docx 38021 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:
Recipients Received:
MEMORANDUM TO: Dennis C. Morey, Chief Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation FROM: Stacey L. Rosenberg, Chief Vessels and Internals Integrity Branch Division of Engineering Office of Nuclear Reactor Regulation
SUBJECT:
SUPPLEMENTAL REQUEST FOR ADDITIONAL INFORMATION ON TIME-LIMITED AGING ANALYSES FOR REACTOR VESSEL NEUTRON EMBRITTLEMENT, DAVIS-BESSE NUCLEAR POWER STATION, LICENSE RENEWAL APPLICATION (TAC NO. ME4640)
The Vessels and Internals Integrity Branch is in the process of reviewing the information that was provided by FirstEnergy Nuclear Operating Company (the applicant) pertaining to the Time-Limited Aging Analyses (TLAAs) of reactor vessel (RV) neutron embrittlement for the Davis-Besse Nuclear Power Station (Davis-Besse). This information was provided by the applicant as part of the Davis-Besse License Renewal Application (LRA), dated August 30, 2010, and its April 15, 2011 response to the staffs request for additional information (RAI).
The staff has identified that additional information is needed to complete the evaluation. The staffs supplemental RAI is enclosed. In order to facilitate an efficient and expeditious completion of the staffs review, a complete response to all of the enclosed RAI questions is requested by July 6, 2012.
Docket No.: 50-346 ENCLOSURE:
Request for Additional Information CONTACT: Chris Sydnor, NRR/DE/EVIB 301-415-6065
MEMORANDUM TO: Dennis C. Morey, Chief Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation FROM: Stacey L. Rosenberg, Chief Vessels and Internals Integrity Branch Division of Engineering Office of Nuclear Reactor Regulation
SUBJECT:
SUPPLEMENTAL REQUEST FOR ADDITIONAL INFORMATION ON TIME-LIMITED AGING ANALYSES FOR REACTOR VESSEL NEUTRON EMBRITTLEMENT, DAVIS-BESSE NUCLEAR POWER STATION, LICENSE RENEWAL APPLICATION (TAC NO. ME4640)
The Vessels and Internals Integrity Branch is in the process of reviewing the information that was provided by FirstEnergy Nuclear Operating Company (the applicant) pertaining to the Time-Limited Aging Analyses (TLAAs) of reactor vessel (RV) neutron embrittlement for the Davis-Besse Nuclear Power Station (Davis-Besse). This information was provided by the applicant as part of the Davis-Besse License Renewal Application (LRA), dated August 30, 2010, and its April 15, 2011 response to the staffs request for additional information (RAI).
The staff has identified that additional information is needed to complete the evaluation. The staffs supplemental RAI is enclosed. In order to facilitate an efficient and expeditious completion of the staffs review, a complete response to all of the enclosed RAI questions is requested by July 6, 2012.
Docket No.: 50-346 ENCLOSURE:
Request for Additional Information CONTACT: Chris Sydnor, NRR/DE/EVIB 301-415-6065 DISTRIBUTION: DE r/f RidsNrrPMDavisBesse AHiser SCuadradoDeJesus CSydnor SRosenberg ADAMS ACCESSION NO.:
OFFICE NRR/DE/EVIB NRR/DE/EVIB NAME CSydnor SRosenberg DATE 04/ /2012 04/ /2012 OFFICIAL RECORD COPY
SUPPLEMENTAL REQUEST FOR ADDITIONAL INFORMATION LICENSE RENEWAL APPLICATION, SECTION 4.2 TIME-LIMITED AGING ANALYSES OF NEUTRON EMBRITTLEMENT DAVIS-BESSE NUCLEAR POWER STATION FIRST ENERGY NUCLEAR OPERATING COMPANY DOCKET NO. 50-346 RAI 4.2.2 Upper Shelf Energy (USE) Evaluation BACKGROUND LRA Table 4.2-2 lists a generic initial USE of 70 ft-lbs for all Linde 80 reactor vessel (RV) beltline welds (Weld Nos. WF-232, WF-233, and WF-182-1). In its April 15, 2011 response to RAI 4.2.2-2, the applicant stated that 70 ft-lbs is based on a statistical analysis of measured initial USE data from archived Linde 80 weld specimens from plant-specific surveillance capsules. The applicant stated that the initial USE data and the statistical analysis is reported in B&W Owners Group (B&WOG) Topical Report BAW-1803, Correlations for Predicting the Effects of Neutron Radiation on Linde 80 Submerged-Arc Welds, Revision 1, May 1991.
ISSUE The staff has concerns with the use of a generic initial USE of 70 ft-lbs for Linde 80 welds for implementation in direct projections of end-of-license (EOL) USE for the period of extended operation (52 EFPY), for the following reasons:
- 1. The mean value from a database has generally not been acceptable to the staff for establishing a generic initial USE value for a specification, class, and/or type of RV material because generic mean values are not statistically defensible for embrittlement calculations. In the past, the staff has generally only accepted generic initial USE values if they are based on a statistically-conservative position, such as the mean value minus two standard deviations, or the lowest value in the database.
- 2. The BAW-1803 initial USE database has not been reviewed and approved by the staff as a statistical basis for the selection of any generic initial USE value for Linde 80 welds.
REQUEST To demonstrate acceptable USE for the RV beltline materials, WF-232 and WF-233, provide a response to either (a) or (b):
(a) Provide a direct projection of USE through 52 EFPY based on either (i) measured heat-specific initial USE values from certified material test reports (CMTRs), or (ii) a statistically-based conservative generic initial USE value, along with a technical justification for the value.
(b) Provide EMAs for weld materials WF-232 and WF-233 in the shell region of the RV, which may use the existing methods developed in B&WOG Topical Reports BAW-2191P-A and BAW-2178P-A, or the ASME Code,Section XI, Appendix K, accounting for neutron embrittlement through 52 EFPY. EMAs for non-shell welds must use applied J-integral values based on the specific weld geometry.
RAI 4.2.4 Pressure-Temperature (P-T) Limits BACKGROUND LRA Section 4.2.4 describes the methods used to develop P-T limit curves for Davis-Besse. As stated in LRA Section 4.2.4, the Davis-Besse P-T limit curves are established in a P-T Limits Report (PTLR), the contents of which are controlled in accordance with Technical Specification 5.6.6 requirements. The current Davis-Besse PTLR contains P-T limit curves that are valid through 32 EFPY. These P-T limit curves were calculated using adjusted RTNDT values for the limiting RV beltline shell material.
10 CFR Part 50, Appendix G, Fracture Toughness Requirements, states, this appendix specifies fracture toughness requirements for ferritic materials of pressure-retaining components of the reactor coolant pressure boundary (RCPB) of light water nuclear power reactors to provide adequate margins of safety In addition, 10 CFR Part 50, Appendix G, Paragraph IV.A states that, the pressure-retaining components of the RCPB that are made of ferritic materials must meet the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code), supplemented by the additional requirements set forth in [paragraph IV.A.2, Pressure-Temperature (P-T) Limits and Minimum Temperature Requirements"] Therefore, 10 CFR Part 50, Appendix G requires that P-T limits be developed for the entire RCPB, consisting of ferritic RCPB materials in the RV beltline (neutron fluence 1 x 1017 n/cm2, E > 1 MeV), as well as ferritic RCPB materials not in the RV beltline (neutron fluence < 1 x 1017 n/cm2, E > 1 MeV).
ISSUE P-T limit calculations for ferritic RCPB components that are not RV beltline shell materials, may define curves that are more limiting than those calculated for the RV beltline shell materials.
This may be due to the following factors:
- 1. Some ferritic RCPB components that are not RV beltline shell materials, such as nozzles, penetrations, and other discontinuities, are complex geometry components that exhibit significantly higher stresses than those for the RV beltline region. These higher stresses can potentially result in more restrictive P-T limits, even if the reference
temperature (RTNDT) for these components is not as high as that of RV beltline materials that have simpler geometries.
- 2. Ferritic RCPB components that are not RV beltline shell materials may have material properties, in particular initial RTNDT values, which may define more restrictive P-T limits that those for the RV beltline shell materials.
REQUEST Describe how the P-T limit curves, and the methodology used to develop these curves, considered all ferritic RCPB materials, consistent with the requirements of 10 CFR Part 50, Appendix G.