ML110240122
| ML110240122 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 01/24/2011 |
| From: | Plant Licensing Branch III |
| To: | |
| Feintuch K, NRR/DORL/LPL3-1, 415-3079 | |
| References | |
| TAC ME4984 | |
| Download: ML110240122 (2) | |
Text
Script read by Mathew Mitchell, Chief of the Office of Nuclear Reactor Regulations Vessels and Internals Integrity Branch on November 15, 2010 to the staff of Duane Arnold Energy Center (DAEC), with DAEC staff attendance coordinated by Thomas Byrne of DAEC.
By letters dated November 6, and November 10, 2010, NextEra Energy Duane Arnold, LLC (the licensee) submitted, and revised, a request for an alternative for Duane Arnold Energy Center (DAEC) from certain American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) requirements under the provisions of Title 10 of the Code of Federal Regulations 50.55a(a)(3)(i). The licensees November 10, 2010 submittal was a complete revision of the original November 6, 2010 submittal. The licensees November 10, 2010 submittal will be referenced consistently throughout the rest of this discussion.
Specifically, the licensee requested permission to implement a weld overlay repair in accordance with the provisions of ASME Code Case N-504-4, "Alternative Rules for Repair of Classes 1, 2, and 3 Austenitic Stainless Steel Piping," including the conditions required by U. S.
NRC Regulatory Guide 1.147, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1, for the RRA-F002A Recirculation Inlet Safe End-to-Safe End Extension Weld with the exception that some of the base metals and filler metals being overlayed are nickel-based austenitic alloy materials instead of all austenitic stainless steels. The weld overlay repair is being implemented to address unacceptable flaw indications discovered during inspection of the subject weld during the DAEC fall 2010 refueling outage. The weld overlay repair is being implemented as an alternative to meeting specific requirements in ASME Code,Section XI, Article IWA-4000 as identified in the licensees November 10, 2010 submittal.
The licensees proposed alternative with regard to the implementation of weld overlay repair and the nondestructive examination of the weld overlay after installation was documented in the licensees November 10, 2010 letter. Specifically, this included information on:
- 1. the materials with which the weld overlay would be manufactured
- 2. the materials to which the overlay may be applied
- 3. the design requirements the overlay will meet
- 4. the inspection of the original weld prior to application of the overlay, and
- 5. the preservice examination and testing that will be performed on the overlay after installation.
Hence, in accordance with 10 CFR 50.55a(a)(3)(i), the licensee provided information to demonstrate that the proposed alternative would maintain an acceptable level of quality and safety with regard to ensuring the integrity of the DAEC coolant pressure boundary RRA-F002A Recirculation Inlet Safe End-to-Safe End Extension Weld under all licensing basis conditions of operation.
The NRC has completed its review of the information provided in the licensees submittals. The NRC has concluded that the licensee provided adequate information regarding the inspection of the weld prior to overlay application, design features of the weld overlay, installation of the weld overlay, and preservice inspection and testing of the weld overlay to substantiate its implementation as an acceptable alternative repair. Hence, as Chief of the Office of Nuclear
Reactor Regulations Vessels and Internals Integrity Branch, I hereby recommend authorization of the licensses implementation of the proposed alternative for the repair of the RRA-F002A Recirculation Inlet Safe End-to-Safe End Extension Weld during the units fall 2010 refueling outage accordance with the information provided in the licensees letter dated November 10, 2010.
Script read by Robert Pascarelli, Chief of the Office of Nuclear Reactor Regulations Plant Licensing Branch 3-1 during the same conference call to Duane Arnold Energy Center.
As Chief of the Office of Nuclear Reactor Regulations Plant Licensing Branch III-1, I concur with the Vessel and Internals Integrity Branchs conclusions. Based on these conclusions, I conclude that the alternative proposed in the licensees letter dated November 6, 2010, as revised by letter dated November 10, 2010, will provide an acceptable level of quality and safety. Therefore, the licensees proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(i). We expect to follow up formally in writing in the near future.