ML18101A687
| ML18101A687 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 05/03/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18101A686 | List: |
| References | |
| NUDOCS 9505090271 | |
| Download: ML18101A687 (3) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO A REQUEST TO USE AN ALTERNATIVE TO
1.0 INTRODUCTION
ASME CODE SECTION XI PUBLIC SERVICE ELECTRIC AND GAS COMPANY SALEM NUCLEAR GENERATING STATION. UNIT 1 DOCKET NO. 50-272 The Technical Specifications for the Salem Nuclear Generating Station, Unit 1, state that the inservice inspection and testing of the American Society of Mechanical Engineers (ASHE) Code Class 1, 2, and 3 components shall be performed in accordance with Section XI of the ASHE Boiler and Pressure Vessel Code and applicable Addenda as required by Title 10 of the Code of Federal
- Regulations (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 that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (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 difficulties 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 preservice examination requirements, set forth in the ASHE 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 inspection 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) on the date 12 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein.
The applicable edition of Section XI of the ASME Code for the second 10-year inservice inspection (ISi) interval is the 1983 Edition with the Summer 1983 Addenda.
2.0 RELIEF REQUEST In a letter dated March 20, 1995, the licensee is requesting, pursuant to 10 CFR.50.55a(g)(S)(iii), relief to use the 1992 Edition of the ASHE Section XI, Article IWA-4500 for the automatic (machine) Gas Tungsten Arc Welding (GTAW) process when performing a temperbead weld repair on ferrous base materials. The 1992 edition of the ASME Code,Section XI, Article 9505090271 6~gggg7~
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' *, IWA-4500, permits the use of the automatic (machine} GTAW process and F43 filler metal with the temperbead technique without requiring impact testing on the weld deposit of the procedure qualification test assembly; however, the 1992 Edition of the ASME Code has not yet been endorsed by the NRC.
2.1 Licensee's Basis for Requesting Relief "During the 1995 Salem Unit No. 1 twelfth refueling outage (1Rl2}, the feedwater thermal sleeve upgrade project may require weld repair on the steam generator feedwater nozzle inner diameter (ID} surface areas. The nozzle is constructed of SA-508 Class 2 material (P3 - Group 3} which requires post weld heat treatment.
"Because of the change in sectional thickness of the feedwater nozzle along
- its principal axis, post weld heat treatment of these repair welds is extremely difficult and represents undue hardship. Additionally, the performance of any post weld heat treatment would unnecessarily contribute to the total permissible cumulative post weld heat treatment time, qualified during the original construction of the Salem steam generators. Consequently, it is desirable to employ a welding technique that does not require post weld heat treatment.
"The Salem Unit No. 1 commitment to the ASME Code Section XI, 1983 Edition, Summer 1983 Addenda, only permits the use of Shielded Metal Arc Welding process to accomplish such repairs.
An automatic (machine} Gas Tungsten Arc Welding process is preferred to the manual Shielded Metal Arc Welding process.
The Gas Tungsten Arc Welding process is superior for controlling vital process variables, which contribute to the quality of such welds.
"NRC approved Code Case N-432, allows the Gas Tungsten Arc Welding process fot temperbead repairs on Class 1 components.
However, full compliance with this Code Case requires that the welding procedure qualification test assembly be made from the same material (i.e., specification, type, grade, class including a post weld heat treatment at least equivalent to the time and temperature already applied to the material, to the material being repaired}.
When Code Case N-432 was incorporated into the 1992 Edition of the ASME Code,Section XI, some relaxations of these requirements were provided.
"Although the 1992 Edition of the ASME Code has not been approved by the NRC, the 1992 Edition allows the'procedure qualification test assembly to meet the same P number and group number of the material being repaired. This change provides acceptable material properties for the procedure qualification test assembly, without imposing undue complications of replicating the materials for the test assembly to that which is being repaired."
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~ 2.2 Alternate Weld Process Automatic (machine) Gas Tungsten Arc Welding process as provided for in the 1992 Edition of the ASHE Code,Section XI, Article IWA-4500.
2.3 Staff Evaluation The staff has reviewed the licensee's request for relief as a request to use an alternative pursuant to 10 CFR 50.55a(a)(3)(i) since the request is to use a part of a ASME Code edition not yet incorporated by reference in 10 CFR 50.55a(b).
The staff agrees with the licensee that the automatic (machine) GTAW process is inherently superior for controlling important process variables that affect the overall quality of the weld.
The staff further agrees that, in recognition of the low temperature fracture toughness properties of the nickel base alloys, exempting impact testing of non-ferrous materi.als for procedure qualifications is acceptable.
The staff has reviewed the licensee's submittal and has concluded that the use of the provisions of the 1992 Edition of the ASME Code,Section XI, Article*
IWA-4500 in place of ASHE Code, Section.XI, 1983 Edition/Summer 1983 Addenda, which only provides for using the Shielded Metal Arc Welding (SMAW) Process, is an alternative that is sufficient to ensure weld integrity and, thus, provides an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i}, use of licensee's proposed alternative is authorized as requested.
3.0 CONCLUSION
Pursuant to 10 CFR 50.55a(a)(3)(i}, the staff finds the proposed alternative weld process is authorized and will provide an acceptable level of quality and safety for Salem Nuclear Generating Station, Unit I.
Principal Contributor:
T. K. Mclellan Date:
May 3, 1995