ML043630230
| ML043630230 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 12/29/2004 |
| From: | Richard Laufer NRC/NRR/DLPM/LPD1 |
| To: | Shriver B PPL Generation |
| Guzman R, NRR/DLPM 415-1030 | |
| References | |
| TAC MC2380 | |
| Download: ML043630230 (9) | |
Text
December 29, 2004 Mr. Bryce L. Shriver President, PPL Generation, LLC and Chief Nuclear Officer PPL Generation, LLC 2 North Ninth Street Allentown, PA 18101
SUBJECT:
SUSQUEHANNA STEAM ELECTRIC STATION, UNIT 2 - REQUEST TO USE THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) CODE CASE N-663 (TAC NO. MC2380)
Dear Mr. Shriver:
In a letter dated March 5, 2004, PPL Susquehanna, LLC (PPL, the licensee), submitted Relief Request No. 27, proposing an alternative to the 1989 Edition of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI requirements for inservice inspection (ISI) programs at Susquehanna Steam Electric Station, Unit 2 (SSES 2). In lieu of the ASME Code requirements, PPL proposes to use ASME Code Case-663, Alternative Requirements for Class 1 and 2 Surface Examinations, as an alternative to the surface examination requirements of Class 1, Examination Categories B-F and B-J piping welds (N8A and N8B nozzles) at SSES 2.
The applicable inspection interval for this request is the second 10-year ISI interval which began on June 1, 1994, and ended on May 31, 2004. The ISI Code of record for the second 10-year interval is the 1989 Edition with no Addenda of the ASME Code.
Based on the information provided by PPL, the Nuclear Regulatory Commission (NRC) staff concluded on May 24, 2004, that the proposed alternative will provide an acceptable level of quality and safety and that the use of the proposed alternative is authorized pursuant to Title 10 of the Code of Federal Regulations, Part 50, Section 50.55a(a)(3)(i) for the second 10-year ISI interval. This letter documents the NRC staffs conclusion of acceptability. The NRC staffs safety evaluation is enclosed.
If you have any questions, please contact Rich Guzman, at (301) 415-1030.
Sincerely,
/RA by Peter Tam for/
Richard J. Laufer, Chief, Section 1 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-388
Enclosure:
Safety Evaluation cc w/encl: See next page
Mr. Bryce L. Shriver President, PPL Generation, LLC and Chief Nuclear Officer PPL Generation, LLC 2 North Ninth Street Allentown, PA 18101
SUBJECT:
SUSQUEHANNA STEAM ELECTRIC STATION, UNIT 2 - REQUEST TO USE THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) CODE CASE N-663 (TAC NO. MC2380)
Dear Mr. Shriver:
In a letter dated March 5, 2004, PPL Susquehanna, LLC (PPL, the licensee), submitted Relief Request No. 27, proposing an alternative to the 1989 Edition of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI requirements for inservice inspection (ISI) programs at Susquehanna Steam Electric Station, Unit 2 (SSES 2). In lieu of the ASME Code requirements, PPL proposes to use ASME Code Case-663, Alternative Requirements for Class 1 and 2 Surface Examinations, as an alternative to the surface examination requirements of Class 1, Examination Categories B-F and B-J piping welds (N8A and N8B nozzles) at SSES 2.
The applicable inspection interval for this request is the second 10-year ISI interval which began on June 1, 1994, and ended on May 31, 2004. The ISI Code of record for the second 10-year interval is the 1989 Edition with no Addenda of the ASME Code.
Based on the information provided by PPL, the Nuclear Regulatory Commission (NRC) staff concluded on May 24, 2004, that the proposed alternative will provide an acceptable level of quality and safety and that the use of the proposed alternative is authorized pursuant to Title 10 of the Code of Federal Regulations, Part 50, Section 50.55a(a)(3)(i) for the second 10-year ISI interval. This letter documents the NRC staffs conclusion of acceptability. The NRC staffs safety evaluation is enclosed.
If you have any questions, please contact Rich Guzman, at (301) 415-1030.
Sincerely,
/RA by Peter Tam for/
Richard J. Laufer, Chief, Section 1 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-388
Enclosure:
Safety Evaluation cc w/encl: See next page DISTRIBUTION:
PUBLIC PDI-1 RF RLaufer TChan ACRS RGuzman MOBrien GHill (2) OGC GMatakas, Rgn-1 ZFu CMiller, EDO, RGN-I DLPM DPR ACCESSION NO.: ML043630230 *SE provided. No major changes made.
OFFICE PDI-1/PM PDI-2/LA EMEB/SC* OGC PDI-1/SC NAME RGuzman MO'Brien TChan SLewis PTam for RLaufer DATE 12/20/04 12/13/04 5/24/04 SE DTD 12/23/04 12/29/04 OFFICIAL RECORD COPY
Susquehanna Steam Electric Station, Unit Nos. 1 and 2 cc:
Britt T. McKinney Michael H. Crowthers Vice President - Nuclear Site Operations Supervising Engineer PPL Susquehanna, LLC Nuclear Regulatory Affairs 769 Salem Blvd., NUCSB3 PPL Susquehanna, LLC Berwick, PA 18603-0467 Two North Ninth Street, GENPL4 Allentown, PA 18101-1179 Robert A. Saccone Vice President - Nuclear Operations Dale F. Roth PPL Susquehanna, LLC Manager - Quality Assurance 769 Salem Blvd., NUCSB3 PPL Susquehanna, LLC Berwick, PA 18603-0467 769 Salem Blvd., NUCSB2 Berwick, PA 18603-0467 Aloysius J. Wrape, III General Manager - Nuclear Assurance Luis A. Ramos PPL Susquehanna, LLC Community Relations Manager, Two North Ninth Street, GENPL4 Susquehanna Allentown, PA 18101-1179 PPL Susquehanna, LLC 634 Salem Blvd., SSO Terry L. Harpster Berwick, PA 18603-0467 General Manager - Plant Support PPL Susquehanna, LLC Bryan A. Snapp, Esq 769 Salem Blvd., NUCSA4 Assoc. General Counsel Berwick, PA 18603-0467 PPL Services Corporation Two North Ninth Street, GENTW3 Gregory F. Ruppert Allentown, PA 18101-1179 General Manager - Nuclear Engineering PPL Susquehanna, LLC Supervisor - Document Control Services 769 Salem Blvd., NUCSB3 PPL Susquehanna, LLC Berwick, PA 18603-0467 Two North Ninth Street, GENPL4 Allentown, PA 18101-1179 Rocco R. Sgarro Manager - Nuclear Regulatory Affairs Richard W. Osborne PPL Susquehanna, LLC Allegheny Electric Cooperative, Inc.
Two North Ninth Street, GENPL4 212 Locust Street Allentown, PA 18101-1179 P.O. Box 1266 Harrisburg, PA 17108-1266 Walter E. Morrissey Supervising Engineer Director - Bureau of Radiation Protection Nuclear Regulatory Affairs Pennsylvania Department of PPL Susquehanna, LLC Environmental Protection 769 Salem Blvd., NUCSA4 P.O. Box 8469 Berwick, PA 18603-0467 Harrisburg, PA 17105-8469
Susquehanna Steam Electric Station, Unit Nos. 1 and 2 cc:
Senior Resident Inspector U.S. Nuclear Regulatory Commission P.O. Box 35, NUCSA4 Berwick, PA 18603-0035 Regional Administrator, Region 1 U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Board of Supervisors Salem Township P.O. Box 405 Berwick, PA 18603-0035 Dr. Judith Johnsrud National Energy Committee Sierra Club 443 Orlando Avenue State College, PA 16803
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO RELIEF REQUEST NO. 27 TO USE AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) CODE CASE-663 AS AN ALTERNATIVE TO THE SURFACE EXAMINATION REQUIREMENTS OF ASME, SECTION XI, TABLE IWB-2500-1 FOR PPL SUSQUEHANNA, LLC SUSQUEHANNA STEAM ELECTRIC STATION, UNIT 2 DOCKET NO. 50-388
1.0 INTRODUCTION
By letter dated March 5, 2004, PPL Susquehanna, LLC (PPL, the licensee), submitted Relief Request No. 27, proposing an alternative to the 1989 Edition of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI requirements for inservice inspection (ISI) programs at Susquehanna Steam Electric Station, Unit 2 (SSES 2). The applicable inspection interval for this relief request is the second 10-year ISI interval which began on June 1, 1994, and ended on May 31, 2004. The ISI Code of record for the second 10-year interval for SSES 2 is the 1989 Edition with no Addenda of the ASME Code,Section XI.
The ISI of the ASME Code, Class 1, 2, and 3 components is to be performed in accordance with Section XI of the ASME Code and applicable edition and addenda as required by Title 10 of the Code of Federal Regulations, Part 50, Section 50.55a(g) (10 CFR 50.55a(g)), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). Section 50.55a(a)(3) states in part that alternatives to the requirements of paragraph (g) may be used, when authorized by the Nuclear Regulatory Commission (NRC),
if the licensee 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) shall meet the requirements, except the design and access provisions and the pre-service examination requirements, set forth in the ASME Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," 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 components (including supports) may meet the requirements set forth in subsequent editions and addenda of the ASME Code incorporated by reference in 10 CFR 50.55a(b) subject to the limitations and modifications listed therein and subject to Commission approval.
2.0 REGULATORY EVALUATION
2.1 Code Requirements The 1989 Edition of the ASME Code,Section XI, IWB-2500 requires components be examined and tested as specified in Table IWC-2500-1. These tables require 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 (i.e., visual, VT-2).
2.2 PPLs Code Relief Request and its Proposed Alternative PPL proposes to use ASME Code Case N-663 as an alternative to the surface examination requirements of Section XI, Table IWB-2500-1, Examination Categories B-F and B-J. All areas of the subject welds identified as susceptible to outside surface attack shall be surface examined in accordance with Code Case N-663.
2.3 Components for which Relief Is Requested Section XI, IWB-2500-1, Examination Categories B-F and B-J, Item Numbers B5.10 and B9.11, Class 1 piping welds (NPS 4 and larger).
2.4 PPLs Basis for the Proposed Alternative The ASME Code, Section Xl, Task Group on ISI 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 that only 2 welds (0.02%) were found to have flaws detected by Section Xl surface examinations, with 50 units responding and a total of 9,333 welds inspected. These flaws were determined to be fabrication-induced.
In parallel with the above, several risk-informed ASME 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-informed piping examinations is through the use of Electric Power Research Institute (EPRI) TR-112657, Revision B, Revised Risk-Informed Inservice Inspection Evaluation Procedure, approved by an NRC Safety Evaluation Report dated October 28, 1999 (Agencywide Documents Access and Management System Accession No. ML993190474).
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 outside diameter (O.D.) chloride cracking. These two initiatives led ASME to investigate the value of surface examinations.
Code Case N-663 incorporates lessons learned from the risk-informed initiatives and industry examination experience into Section Xl 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 O.D. degradation is most likely to occur by reviewing plant-specific programs, 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 unnecessary examinations. Other ASME Code,Section XI, examination requirements (subject to approved relief requests) for the subject welds, including volumetric examinations and pressure testing, will continue to be performed.
3.0 TECHNICAL EVALUATION
The proposed use of Code Case N-663 by PPL to replace the ASME Code,Section XI, required surface examinations for piping welds of Examination Categories B-F and B-J 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.
With regard to the current issue of surface examinations for piping welds of Examination Categories B-F and B-J, all plants that performed risk-informed ISI of their Class 1 piping systems in accordance with the topical reports referenced above arrived at the conclusion that the only degradation mechanism that requires surface examination is O.D. chloride cracking.
Consequently, within these plants, surface examination should be considered only when O.D.
chloride cracking is identified as the degradation mechanism affecting the structural integrity of the subject piping welds.
Code Case N-663 provides that ...in lieu of the surface examination requirements for piping welds of Examination Categories B-F (NPS 4 and larger), B-J (NPS 4 and larger)..., surface examinations may be limited to areas identified by the Owner as susceptible to outside surface attack. The susceptibility criteria are listed in Table 1 of Code Case N-663 for two types of degradation mechanisms: 1) external O.D. 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 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 which can result in outside surface attack, and to implement 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.
4.0 CONCLUSION
Based upon review of the information provided by PPL in support of its request for relief, the NRC staff concludes that use of Code Case N-663 for Class 1 surface examinations, in lieu of the Table IWB-2500-1, Examination Categories B-F and B-J requirements, will provide 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. Furthermore, the licensee will be required to conduct a plant-specific service history review to identify, in addition to chloride-induced mechanisms, other possible mechanisms that will cause outside surface attack upon subject plant components. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), PPLs proposed use of Code Case N-663 is authorized for SSES 2, for the second 10-year ISI interval, or until Code Case N-663 is published in a future version of Regulatory Guide (RG) 1.147. At that time, if PPL intends to continue implementing this code case, PPL must follow all provisions of Code Case N-663, if any, with limitations or conditions specified in RG 1.147. All other requirements of the ASME Code,Section XI, for which relief has not been specifically requested remain applicable, including third party review by the authorized nuclear inservice inspector.
Principal Contributor: Z. Bart Fu Date: December 29, 2004