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

{{Adams
| number = ML040920323
| issue date = 04/05/2004
| title = Use of Code Cases N-588, N-640, and N-641 in Developing Pressure-Temperature Operating Limits
| author name = Beckner W
| author affiliation = NRC/NRR/DIPM/IROB
| addressee name = 
| addressee affiliation = 
| docket = 
| license number = 
| contact person = Ray, Nihar NRR/DE/EMCB, 415-2643
| case reference number = TAC MC1593
| document report number = RIS-04-004
| document type = NRC Regulatory Issue Summary
| page count = 5
}}
{{#Wiki_filter:UNITED STATES
                            NUCLEAR REGULATORY COMMISSION
                        OFFICE OF NUCLEAR REACTOR REGULATION
                                WASHINGTON, D.C. 20555-0001 April 5, 2004 NRC REGULATORY ISSUE SUMMARY 2004-04:
     USE OF CODE CASES N-588, N-640, AND N-641 IN DEVELOPING
                PRESSURE-TEMPERATURE OPERATING LIMITS

==ADDRESSEES==
All holders of construction permits or operating licenses for nuclear power reactors except those who 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 vessel pressure-temperature limits using ASME Section XI, Appendix G. This RIS does not require any 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 that pressure-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 fracture mechanics 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 reference defects in all axial welds and base metal and circumferentially oriented reference defects in all circumferential welds. Code Case N-640 allows the use of KIC ( which is the material toughness property measured in terms of stress intensity factor, Ki, which will lead to nonductile crack propagation) instead of KIA (which is the critical value of the stress intensity factor, KI, for crack arrest 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 use editions and addenda of Appendix G to Section XI of the ASME Code incorporated into a facilitys licensing basis (i.e., through their defined facility inservice inspection program) for the purpose 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 10
CFR 50.55a. In summary:
         Licensees may use the provisions of any edition and addenda of ASME Code Section XI, 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) in conjunction 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 licensees Technical Specifications or modifying a facilitys 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 under
10 CFR 50.109. Consequently, the staff did not perform a backfit analysis. SMALL BUSINESS REGULATORY ENFORCEMENT FAIRNESS ACT
The NRC has determined that this action is not subject to the Small Business Regulatory Enforcement Fairness Act of 1996.

===FEDERAL REGISTER NOTIFICATION===
A notice of opportunity for public comment on this RIS was not published in the Federal Register because the RIS is informational.

===PAPERWORK REDUCTION ACT STATEMENT===
This RIS does not contain information collections and, therefore, is not subject to the requirements of Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.).
                                   Public Protection Notification The NRC may not conduct or sponsor, and a person is not required to respond to, an information 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 the appropriate 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 Regulation Technical contact:     Nihar K. Ray, NRR
                       301-415-2643 E-mail: nkr@nrc.gov Attachment: List of Recently Issued Regulatory Issue Summaries

ML040920323 DOCUMENT NAME: C:\ORPCheckout\FileNET\ML040920323.wpd OFFICE EMCB:DE            Tech Editor     SC:EMCB:DE BC:EMCB:DE          OES:IROB:DIPM
  NAME     NKRay            PKleene         SMCoffin         WHBateman     CPetrone DATE     03/01/2004       02/25/2004      03/02/2004       03/08/2004    03/01/2004 OFFICE   OGC              OGC             OCIO             CRGR          SC:OES:IROB:DIPM
  NAME     CMHolzle         RWeisman        BCSt.Mary        Cader *email  TReis DATE     03/26/2004       03/23/2004      03/25/2004       03/09/2004       /      /2004 OFFICE   C:IROB:DIPM      OE
  NAME     WDBeckner        CNoland DATE     04/05/2004       04/01/2004         /     /2004     /     /2004    /      /2004

Attachment LIST OF RECENTLY ISSUED
                                  NRC REGULATORY ISSUE SUMMARIES
_____________________________________________________________________________________
Regulatory Issue                                            Date of Summary No.                  Subject                      Issuance       Issued to
_____________________________________________________________________________________
2004-03          Risk-informed Approach For Post-           03/02/2004 All holders of operating licenses Fire Safe-Shutdown Associated                         for nuclear power reactors, except Circuit Inspections                                   those who have permanently ceased operations and have certified that fuel has been permanently removed from the reactor vessel.

2004-02          Deferral of Active Regulation of           02/23/2004 All holders of materials licenses Ground-Water Protection at in Situ                    for uranium and thorium recovery Leach Uranium Extraction                              facilities.

Facilities
2004-01          Method for Estimating Effective            02/17/2004 All U.S. Nuclear Regulatory Dose Equivalent from External                         Commission (NRC) licensees.

Radiation Sources Using Two Dosimeters
2003-18          Use of NEI 99-01, Methodology             10/08/2003 All holders of operating licenses for Development of Emergency                          for nuclear power reactors and Action Levels, Revision 4, Dated                     licensees that have permanently January 2003                                          ceased operations and have certified that fuel has been permanently removed from the reactor vessel.

2003-17          Complying with 10 CFR 35.59,               10/03/2003 All U.S. Nuclear Regulatory Recentness of Training, for                         Commission (NRC) medical-use Board-certified Individuals Whose                     licensees and NRC master Training and Experience Were                          materials license medical-use Completed More than 7 Years Ago                       permittees.

Note:             NRC generic communications may be received in electronic format shortly after they are issued by subscribing to the NRC listserver as follows:
                  To subscribe send an e-mail to <listproc@nrc.gov >, no subject, and the following command in the message portion:
                                     subscribe gc-nrr firstname lastname
______________________________________________________________________________________
OL = Operating License CP = Construction Permit
}}

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