RIS 2004-04, Use of Code Cases N-588, N-640, and N-641 in Developing Pressure-Temperature Operating Limits

Use of Code Cases N-588, N-640, and N-641 in Developing Pressure-Temperature Operating Limits

ML040920323
Person / Time
Issue date:	04/05/2004
From:	Beckner W NRC/NRR/DIPM/IROB
To:
Ray, Nihar NRR/DE/EMCB, 415-2643
References
TAC MC1593 RIS-04-004
Download: ML040920323 (5)

UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555-0001April 5, 2004NRC REGULATORY ISSUE SUMMARY 2004-04:USE OF CODE CASES N-588, N-640, AND N-641 IN DEVELOPINGPRESSURE-TEMPERATURE OPERATING LIMITS

ADDRESSEES

All holders of construction permits or operating licenses for nuclear power reactors except thosewho have permanently ceased operations and have certified that fuel has been permanently removed from the reactor vessel.

INTENT

The U.S. Nuclear Regulatory Commission (NRC) is issuing this regulatory issue summary (RIS)to inform addressees of the NRC position on the use of American Society of Mechanical Engineers (ASME) Code Cases N-588, N-640, and N-641 in developing reactor pressure vesselpressure-temperature limits using ASME Section XI, Appendix G.

This RIS does not requireany action or written response on the part of an addressee.

BACKGROUND

Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Appendix G, requires thatpressure-temperature (P-T) limits be established for reactor pressure vessels (RPVs) during normal operating and hydrostatic or leak rate testing conditions. Further, Appendix G of

10 CFR Part 50 specifies that the requirements for these limits are based on the application of evaluation procedures given in Appendix G to Section XI of the American Society of Mechanical Engineers (ASME) Boiler & Pressure Vessel Code (Code).Since ASME Section XI, Appendix G, was first developed, significant advances in fracturemechanics and the analysis of reactor vessel integrity have been achieved. In general, advancements in knowledge are promulgated as ASME Code Cases, for example, Code Cases N-588, N-640, and N-641, which provide alternatives to existing Code requirements for developing pressure-temperature operating limits. These alternatives to the Appendix G

methodology have been proposed and accepted as appropriate alternatives and are documented in Regulatory Guide 1.147, "Inservice Inspection Code Case Acceptability, ASME

Section XI, Division 1." The provisions of ASME Code Cases N-588, N 640, and N-641 that are applicable to P-T limit curve development were incorporated into ASME Code Section XI,

Appendix G in the 1998 edition through 2000 addenda which is the edition and addenda codified in 10 CFR 50.55a, effective October 28, 2002 (67 FR 60520). Code Case N-588 provides an alternative procedure for assuming axially oriented referencedefects in all axial welds and base metal and circumferentially oriented reference defects in all circumferential welds. Code Case N-640 allows the use of K

IC ( which is the material toughnessproperty measured in terms of stress intensity factor, K

i, which will lead to nonductile crackpropagation) instead of K

IA (which is the critical value of the stress intensity factor, K

I, for crackarrest as a function of temperature) in the development of pressure-temperature limit curves.

Code Case N-641 presents alternative procedures for calculating pressure-temperature relationships and low-temperature overpressure protection (LTOP) system effective temperatures and allowable pressures. These procedures take into account alternative fracture toughness properties, circumferential and axial reference flaws, and plant-specific LTOP enable temperature calculations.

SUMMARY OF ISSUE

Historically, the NRC staff has taken the position that licensees are only permitted to useeditions and addenda of Appendix G to Section XI of the ASME Code incorporated into a facility's licensing basis (i.e., through their defined facility inservice inspection program) for thepurpose of meeting the requirements for Appendix G to 10 CFR Part 50. For an example, if a licensee wished to use a less conservative methodology based on the use of an ASME Code Case in order to relax requirements for RPV P-T limit curve development, the licensee needed to obtain an exemption from the requirements of Appendix G to 10 CFR Part 50.Recently, the NRC re-evaluated the relationship between 10 CFR part 50 appendix G and 10CFR 50.55a. In summary:Licensees may use the provisions of any edition and addenda of ASME Code SectionXI, Appendix G incorporated into 10 CFR 50.55a for RPV P-T limit curve development, up to and including the most recently incorporated edition and addenda, without the need for an exemption.Use of NRC approved ASME Code Cases (e.g., N-588, N-640, and N-641) inconjunction with earlier versions of the ASME Code endorsed in 10 CFR 50.55a may also be used for the development of P-T limit curves without the need for an exemption.However, changing the P-T limit curve methodology specified in the licensee

's TechnicalSpecifications or modifying a facility

's pressure-temperature limit report (PTLR)methodology requires NRC staff approval since this is a license amendment.

BACKFIT DISCUSSION

This RIS does not require any action or written response and, therefore, is not a backfit under10 CFR 50.109. Consequently, the staff did not perform a backfit analysis. SMALL BUSINESS REGULATORY ENFORCEMENT FAIRNESS ACTThe NRC has determined that this action is not subject to the Small Business RegulatoryEnforcement Fairness Act of 1996.

FEDERAL REGISTER NOTIFICATION

A notice of opportunity for public comment on this RIS was not published in the FederalRegister because the RIS is informational.

PAPERWORK REDUCTION ACT STATEMENT

This RIS does not contain information collections and, therefore, is not subject to therequirements of Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.).Public Protection NotificationThe NRC may not conduct or sponsor, and a person is not required to respond to, aninformation collection unless the requesting document displays a currently valid OMB control number. If you have any questions about this matter, please contact the person listed below or theappropriate Office of Nuclear Regulatory Regulation (NRR) project manager for a specific vendor or industry group as listed on the NRC Web site./RA/William D. Beckner, Chief Reactor Operations Branch Division of Inspection Program Management Office of Nuclear Reactor RegulationTechnical contact:Nihar K. Ray, NRR301-415-2643 E-mail: nkr@nrc.govAttachment: List of Recently Issued Regulatory Issue Summaries

ML040920323DOCUMENT NAME: C:\ORPCheckout\FileNET\ML040920323.wpdOFFICEEMCB:DETech EditorSC:EMCB:DEBC:EMCB:DEOES:IROB:DIPMNAMENKRayPKleeneSMCoffinWHBatemanCPetroneDATE03/01/200402/25/2004 03/02/200403/08/200403/01/2004OFFICEOGCOGCOCIOCRGRSC:OES:IROB:DIPMNAMECMHolzleRWeismanBCSt.MaryCader *emailTReisDATE03/26/200403/23/200403/25/200403/09/2004 / /2004OFFICEC:IROB:DIPMOENAMEWDBecknerCNolandDATE04/05/200404/01/2004 / /2004 / /2004 / /2004

______________________________________________________________________________________OL = Operating License

CP = Construction PermitAttachment LIST OF RECENTLY ISSUEDNRC REGULATORY ISSUE SUMMARIES

_____________________________________________________________________________________Regulatory Issue Date of Summary No. Subject IssuanceIssued to

_____________________________________________________________________________________2004-03Risk-informed Approach For Post-Fire Safe-Shutdown Associated Circuit Inspections03/02/2004All holders of operating licensesfor nuclear power reactors, except those who have permanently ceased operations and have certified that fuel has been permanently removed from the reactor vessel.2004-02Deferral of Active Regulation ofGround-Water Protection at in SituLeach Uranium Extraction Facilities02/23/2004All holders of materials licensesfor uranium and thorium recovery facilities.2004-01Method for Estimating EffectiveDose Equivalent from External Radiation Sources Using Two Dosimeters02/17/2004All U.S. Nuclear RegulatoryCommission (NRC) licensees.2003-18Use of NEI 99-01," Methodologyfor Development of Emergency Action Levels," Revision 4, DatedJanuary 200310/08/2003All holders of operating licensesfor nuclear power reactors and licensees that have permanently ceased operations and have certified that fuel has been permanently removed from the reactor vessel.2003-17Complying with 10 CFR 35.59,"Recentness of Training," forBoard-certified Individuals Whose Training and Experience Were Completed More than 7 Years Ago10/03/2003All U.S. Nuclear RegulatoryCommission (NRC) medical-use licensees and NRC master materials license medical-use permittees.Note:NRC generic communications may be received in electronic format shortly after they areissued by subscribing to the NRC listserver as follows:To subscribe send an e-mail to <listproc@nrc.gov >, no subject, and the followingcommand in the message portion:subscribe gc-nrr firstname lastname