ML041900031
| ML041900031 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 07/01/2004 |
| From: | Marshall M NRC/NRR/DLPM/LPD2 |
| To: | Gannon C Carolina Power & Light Co |
| Mozafari B,l NRR/DLPM, 415-2020 | |
| References | |
| TAC MC2403, TAC MC2404 | |
| Download: ML041900031 (8) | |
Text
July 1, 2004 Mr. C. J. Gannon, Vice President Brunswick Steam Electric Plant Carolina Power & Light Company Post Office Box 10429 Southport, North Carolina 28461
SUBJECT:
BRUNSWICK STEAM ELECTRIC PLANT, UNITS 1 AND 2 - SAFETY EVALUATION FOR REQUEST FOR RELIEF NO. RR-33 FOR THE THIRD 10-YEAR INSERVICE INSPECTION INTERVAL (TAC NOS. MC2403 AND MC2404)
Dear Mr. Gannon:
By letter dated January 20, 2004, Carolina Power & Light Company (CP&L, the licensee) requested relief for Brunswick Steam Electric Plant (BSEP), Units 1 and 2, from certain surface examination requirements in the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI for piping welds of Examination Category C-F-2, pressure-retaining welds in carbon or low alloy steel piping. In lieu of these examination requirements, CP&L proposed the use of ASME Code Case N-663, Alternative Requirements for Classes 1 and 2 Surface Examinations.
The Nuclear Regulatory Commission (NRC) has reviewed the proposed alternative in the subject relief request (RR). The results are provided in the enclosed Safety Evaluation.
The NRC staff has concluded that the proposed alternative to the ASME Code requirements in RR No. 33 provides an acceptable level of quality and safety and is acceptable. Pursuant to 10 CFR 50.55a(a)(3)(i), the proposed alternative is authorized for the remainder of the third 10-year ISI interval, which is until May 10, 2008, for BSEP Units 1 and 2, unless during those intervals Code Case N-663 is published in a future version of Regulatory Guide (RG) 1.147, "Inservice Inspection Code Case Acceptability--ASME Section XI, Division 1." At that time, if CP&L intends to continue implementing this Code case, it must follow all provisions of Code Case N-663 with limitations or conditions specified in RG 1.147, if any. All other ASME Code,Section XI requirements for which relief was not specifically requested and approved in this relief request remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.
C. Gannon If you have any questions regarding this approval, please contact the Brunswick Project Manager, Brenda Mozafari, at 301-415-2020.
Sincerely,
/RA/
Michael L. Marshall, Acting Chief, Section 2 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-325 and 50-324
Enclosure:
Safety Evaluation cc w/encl: See next page
ML041900031 *No substantive changes made OFFICE PDII-2/PM PDII-2/LA EMCB* OGC PDII-2/SC (A)
NAME BMozafari EDunnington SE dtd McGurren MMarshall DATE 06/24/04 06/30/04 06/04 /2004 07/01/04 07/01/04 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST FROM ASME CODE, SECTION XI, APPENDIX VIII, SUPPLEMENT 10 BRUNSWICK STEAM ELECTRIC PLANT, UNITS 1 AND 2 CAROLINA POWER & LIGHT COMPANY DOCKET NUMBERS 50-325 AND 50-324
1.0 INTRODUCTION
By letter dated January 20, 2004, Carolina Power & Light Company (CP&L, the licensee) requested relief for Brunswick Steam Electric Plant (BSEP), Units 1 and 2, from certain surface examination requirements in the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI for piping welds of Examination Category C-F-2, pressure-retaining welds in carbon or low alloy steel piping. In lieu of these examination requirements, CP&L proposed the use of ASME Code Case N-663, Alternative Requirements for Classes 1 and 2 Surface Examinations.
The Inservice Inspection (ISI) of the ASME Code Class 1, Class 2, and Class 3 components is to be performed in accordance with Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, and applicable edition and addenda as required by 10 CFR 50.55a(g), except when specific relief has been granted by the U.S. Nuclear Regulatory Commission (NRC) pursuant to 10 CFR 50.55a(g)(6)(i). 10 CFR 50.55a(a)(3) states in part that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if the applicant demonstrates that: (i) the proposed alternatives would provide an acceptable level of quality and safety, or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1, 2, and 3 components (including supports) will meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI, to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the first 10-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein. The ISI Code of record for BSEP, Units 1 and 2, for the third 10-year ISI interval is the 1989 Edition, No Addenda.
Enclosure
2.0 DISCUSSION 2.1 System/Component(s) for which Relief is Requested This relief request applies to ASME Section XI Class 2 piping welds, Table IWC-2500-1, Examination Category C-F-2, Item Nos. C5.50, C5.60, and C5.80.
2.2 Code Requirements for which Relief is Requested The 1989 Edition, No Addenda of the ASME Code,Section XI outlines the examination requirements for Class 2 piping welds. Table IWC-2500-1, Examination Category C-F-2, requires a sampling of 7.5 percent but not less than 28 piping welds (as well as other components) be subjected to various types of non-destructive examinations ( i.e., volumetric and/or surface examinations) and pressure testing.
2.3 Licensees Proposed Alternative to the Code The licensee proposed to use ASME Code Case N-663, in its entirety, as an alternative to the surface examination requirements of Table IWC-2500-1 for Examination Category C-F-2 piping welds. The licensee will use this alternative during the remainder of the third 10-year ISI interval, which started May 11, 1998, and will end May 10, 2008.
2.4 Licensees Reason to Request Relief (as stated by the licensee)
The ASME Code,Section XI, IWC-2500, requires surface examinations of the general population of Category C-F-2 welds. The proposed alternative described in ASME Code Case N-663 would require surface examination of areas identified as being susceptible to outside surface attack, thereby avoiding unnecessary examinations and radiological dose while maintaining an acceptable level of quality and safety for the examination of the affected welds.
2.5 Licensees Basis for Relief (as stated by the licensee)
The subject item numbers in the ASME Code,Section XI require a volumetric and/or surface examination on selected piping welds to ensure that generic degradation mechanisms are not active on either the inside diameter (ID) or the outside diameter (OD). However, these welds are selected using a deterministic set of requirements that are not based upon degradation mechanisms. ASME Code Case N-663 provides an alternative to the current ASME Code,Section XI requirements for defining the number and location of surface examinations for piping components.
The ASME Section XI Task Force on Inservice Inspection Optimization, Report No.
92-01-01, Evaluation of Inservice Inspection Requirements for Class 1, Category B-J Pressure Retaining Welds in Piping, dated July 1995, concluded, with 50 units responding with a total of 9,333 welds inspected, only two welds (i.e. 0.02%) were found to have flaws detected by Section XI surface examinations. These flaws were determined to be fabrication-induced.
In parallel with the above, several risk-informed code cases have been developed for use on piping welds (e.g., ASME Code Cases N-560, N-577, and N-578). One of the methods for risk-informing piping examinations is through use of Electric Power Research Institute (EPRI) topical report TR-112657, Revision B-A, Revised Risk-Informed Inservice Inspection Evaluation Procedure, approved by NRC safety evaluation dated October 28, 1999. Table 4-1, Summary of Degradation-Specific Inspection Requirements and Examination Methods, of the EPRI report lists the required degradation mechanisms to be evaluated in Class 1, 2, and 3 piping. It identifies the risk-informed examination method required for each of these degradation mechanisms.
The only degradation mechanism that requires a surface examination is OD chloride cracking. These two initiatives led ASME to investigate the value of surface examinations.
Code Case N-663 incorporated lessons learned from the risk-informed initiatives and industry examination experience into Section XI by requiring that an evaluation be conducted to identify locations, if any, where a surface examination would be of benefit from a generic piping degradation perspective. The results of this evaluation identify where OD degradation is most likely to occur by reviewing plant-specific programs and practices and operating experience. If the potential for degradation is identified, Code Case N-663 defines examination techniques, volumes, and frequencies. As such, implementing Code Case N-663 will identify appropriate locations for surface examination, if any, and eliminate the unnecessary examinations. Other ASME Code,Section XI examination requirements for the subject piping welds, including volumetric examinations and pressure testing, will continue to be performed.
Code Case N-663 was approved by the ASME Boiler and Pressure Vessel Code Committee on September 12, 2002, but has not yet been included in the most recent listing of NRC-approved code cases provided in Revision 13 of Regulatory Guide (RG) 1.147, Inservice Inspection Code Case Applicability-ASME Section XI Division 1.
2.6 Evaluation The proposed use of Code Case N-663 by CP&L to replace the existing surface examination requirements for examination category C-F-2 piping welds in ASME Code Section XI is consistent with the approved underlying EPRI and Westinghouse methodologies on risk-informed ISI contained in TR-112657, Revision B-A, and WCAP-14572, Revision 1-NP-A, Westinghouse Owners Group Application of Risk-Informed Methods to Piping Inservice Inspection Topical Report. Although the two topical reports use different approaches, both have reached their objectives of identifying the risk-important areas of the piping systems and defining the appropriate examination methods, examination volumes, procedures, and evaluation standards necessary to address the degradation mechanisms of concern and the ones most likely to occur at each location to be inspected. Risk-informed ISI analyzes specific pipe segments for probability of failure and operational safety significance.
In regard to the current issue of surface examinations for piping welds of Examination Category C-F-2, all plants that performed risk-informed ISI of their Class 2 piping systems in accordance
with the topical reports referenced above resulted in the conclusion that the only degradation mechanism that required surface examination is OD chloride cracking. Consequently, within these plants, surface examination would be considered only when OD chloride cracking is identified to be the degradation mechanism affecting the structural integrity of the subject piping welds.
Code Case N-663 states, in part, that ... in lieu of the surface examination requirements for piping welds of Examination Category B-F (NPS 4 and larger), B-J (NPS 4 and larger), C-F-1, and C-F-2, surface examinations may be limited to areas identified by the Owner as susceptible to outside cracking. The susceptibility criteria are listed in Table 1 of Code Case N-663 for two types of degradation mechanisms: 1) external (OD) chloride stress corrosion cracking, and
- 2) other outside surface-initiated mechanisms. These other outside surface-initiated mechanisms include thermal fatigue, boric acid corrosion, and any other Owner-identified mechanisms. The NRC staff determined that the surface inspection requirements of Code Case N-663 are acceptable because the inspection requirements defined in the Code Case are comparable to the corresponding inspection requirements approved by the NRC and adopted by using risk-informed ISI programs. Further, the Code case requires that licensees conduct a plant-specific service history review to identify other mechanisms that can result in outside surface attack and to include plant-specific processes and programs that minimize chlorides and other contaminants. Hence, the alternative provides reasonable assurance that the proposed inspections will not lead to degraded piping performance when compared to the existing performance levels.
3.0 CONCLUSION
Based upon review of the information provided by CP&L in support of its request for relief RR-33, the NRC staff concludes that the use of Code Case N-663 for Class 2 surface examinations, in lieu of the Table IWC-2500-1, Examination Category C-F-2 requirements, provides an acceptable level of quality and safety. This conclusion is based on the fact that inspection requirements defined in Code Case N-663 are comparable to the inspection requirements adopted by plants employing risk-informed ISI programs, and because the licensee will be required to conduct a plant-specific service history review to identify other possible mechanisms besides chloride-induced mechanisms that will cause outside surface attack upon subject plant components. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), CP&Ls proposed use of Code Case N-663 is authorized during the third 10-year ISI interval for BSEP, Units 1 and 2, Class 2 piping welds on the basis that the request provides an acceptable level of quality and safety until Code Case N-663 is referenced in a future revision of Regulatory Guide (RG) 1.147. At that time, if the licensee intends to continue implementing this Code case, the licensee must follow all provisions of Code Case N-663 with limitations or conditions specified in RG 1.147, if any. All other ASME Code,Section XI requirements for which relief was not specifically requested and approved in this relief request remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.
Principal Contributor: R. Rodriguez Date: July 1, 2004
Mr. C. J. Gannon Brunswick Steam Electric Plant Carolina Power & Light Company Units 1 and 2 cc:
Steven R. Carr State of North Carolina Associate General Counsel - Legal Post Office Box 629 Department Raleigh, North Carolina 27602 Progress Energy Service Company, LLC Post Office Box 1551 Mr. Robert P. Gruber Raleigh, North Carolina 27602-1551 Executive Director Public Staff - NCUC Mr. David R. Sandifer, Chairperson 4326 Mail Service Center Brunswick County Board of Commissioners Raleigh, North Carolina 27699-4326 Post Office Box 249 Bolivia, North Carolina 28422 Mr. William C. Noll Director - Site Operations Resident Inspector Brunswick Steam Electric Plant U. S. Nuclear Regulatory Commission Carolina Power & Light Company 8470 River Road Post Office Box 10429 Southport, North Carolina 28461 Southport, North Carolina 28461-0429 Mr. John H. ONeill, Jr. Mr. Norman R. Holden, Mayor Shaw, Pittman, Potts & Trowbridge City of Southport 2300 N Street NW. 201 East Moore Street Washington, DC 20037-1128 Southport, North Carolina 28461 Ms. Beverly Hall, Section Chief Mr. Warren Lee Division of Radiation Protection Emergency Management Director N.C. Department of Environment New Hanover County Department of and Natural Resources Emergency Management 3825 Barrett Dr. Post Office Box 1525 Raleigh, North Carolina 27609-7721 Wilmington, North Carolina 28402-1525 Mr. David H. Hinds Mr. James W. Holt, Manager Plant General Manager Performance Evaluation and Brunswick Steam Electric Plant Regulatory Affairs PEB 7 Carolina Power & Light Company Progress Energy Post Office Box 10429 Post Office Box 1551 Southport, North Carolina 28461-0429 Raleigh, North Carolina 27602-1551 Public Service Commission Mr. Edward T. ONeil State of South Carolina Manager - Support Services Post Office Drawer 11649 Brunswick Steam Electric Plant Columbia, South Carolina 29211 Carolina Power & Light Company Post Office Box 10429 Ms. Margaret A. Force Southport, North Carolina 28461 Assistant Attorney General