NL-08-0311, Response to NRC Request for Additional Information Regarding Application of a Dissimilar Metal Weld Full-Structural Weld Overlay
| ML080590566 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 02/28/2008 |
| From: | David Jones Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-08-0311 | |
| Download: ML080590566 (5) | |
Text
David H. Jones Southern Nuclear Vice President Operating Company, Inc.
Engineering 40 Inverness Center Parkway Birmingham, Alabama 35242 Tel 205.992.5984 Fax 205.992.0341 SOUTHE-A COMPANY February 28, 2008 Energy to Serve }'ourWorM""
Docket No.:
50-321 NL-08-0311 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant - Unit 1 Response to NRC Request for Additional Information Regarding Application of a Dissimilar Metal Weld Full-Structural Weld Overlay Ladies and Gentlemen:
By letter dated February 26, 2008 Southern Nuclear Operating Company (SNC) requested NRC approval of proposed alternative ISI-ALT-08-01, Version 1.0 to allow the application of a full-structural weld overlay over weld 1C11-1CRD-3-R 18A, pursuant to 10 CFR 50.55a(a)(3)(i). On February 27,2008 the NRC provided an e-mail Request for Additional Information (RAI) to SNC. Additionally, these RAls were discussed in a telephone conversation between SNC and the NRC on February 28, 2008.
The SNC response to the NRC RAls is provided in Enclosure 1. If you have any questions, please contact Ray Baker at 205-992-7367.
D. H. Jo Vice President - Engineering DHJ/MNW/daj
Enclosure:
- 1. SNC Responses to NRC Request for Additional Information Regarding Proposed Alternative ISI-ALT-08-01, Version 1.0
U. S. Nuclear Regulatory Commission NL-08-0311 Page 2 cc:
Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. D. R. Madison, Vice President - Hatch RTYPE: CHA02.004 U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Acting Regional Administrator Mr. R. E. Martin, NRR Project Manager - Hatch Mr. J. A. Hickey, Senior Resident Inspector - Hatch
Edwin I. Hatch Nuclear Plant Proposed Alternative in Accordance with 10 CFR 50.55a(a)(3)(i)
Application of a Dissimilar Metal Weld Full-Structural Weld Overlay SNC Response to Request for Additional Information SNC Response to Request for Additional Information E1 - 1 OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR ADDITIONAL INFORMATION EDWIN I. HATCH PLANT UNIT 1 SOUTHERN COMPANY REQUEST FOR STRUCTURAL OVERLAY DOCKET NO. 50-321 The Nuclear Regulatory Commission (NRC) staff has reviewed the Southern Company (the licensee) request dated February, 26, 2008, for application of a dissimilar metal weld full structural overlay at the Edwin I. Hatch Plant, Unit 1, and has determined that additional information is necessary to complete the review of their request for relief. Based on the staffs review, please provide a response which addresses the following request for additional information (RAI) questions.
NRC Question 1 Since the ASME Code,Section XI, Code Case N-504-3 became effective as of December 19, 2007, the staff recommends that it should use Code Case N-504-3 in lieu of Code Case N-504-2.
SNC Response For the preparation of this alternative, Southern Nuclear Operating Company (SNC) initiated discussions with the NRC staff on February 25, 2008 regarding the development of an alternative for a full-structural weld overlay on the CRD return nozzle N9. It was agreed that SNC would develop the alternative based on the technical information previously submitted in ISI-GEN-ALT-07-01, Version 2.0, which was submitted on December 26, 2007 for Farley Nuclear Plant and the Vogtle Electric Generating Plant. ISI-GEN-ALT-07-01, Version 2 references Code Case N-504-2 and provides a comparison of Code Case N-504-2 to the technical content in ISI-GEN-ALT-07-01, Version 2. Therefore, since ISI-GEN-ALT-07-01, Version 2 referenced Case N-504-2, this alternative for Hatch Nuclear Plant Unit 1 (HNP-1) also referenced Case N-504-2.
NRC Question 2 The licensee has stated that the weld overlay of the dissimilar metal welds may require welding no more than 300 square inches of surface on the steel base material. What is the specific maximum area of the carbon or low alloy steel material for that will be welded on? This should be stated in Relief Request for each component to be overlayed.
SNC Response CRD return nozzle N9 is a small diameter nozzle with a design circumference of approximately
- 17. If it is determined that the overlay will be extended out to the nozzle radius as shown in Appendix 6, Figure 2, the overlay length from the edge of the weld to the nozzle would not exceed 5.5 inches; therefore, the maximum area of the overlay in this region is less than 94 square inches.
SNC Response to Request for Additional Information E1 - 2 NRC Question 3 Provide the American Society of Mechanical Engineers (ASME) SA or American Society for Testing and Materials (ASTM) material and grade or class of materials for each component to be overlayed.
SNC Response GE document titled, Hydraulic System Return Nozzle, is a controlled document within SNCs Appendix B program. Per this document, the nozzle material is SA-508, Class II (P No. 3) and the Cap material is SB-166 (P No. 43). The weld material is Alloy 82/182 (F No. 43).
NRC Question 4 Since full ultrasonic examination of the final weld surface and band area (1.5T width) as required by Code Case N-638-1 will not be performed, provide a detailed explanation for the basis for these alternative examinations. Figure 1 in Appendix 2 indicates that no UT examination will be performed beyond AD into the nozzle. Since this area is not volumetrically inspected, any cracks in the nozzle underneath the overlay will not be detected. Provide an explanation for not performing UT in this area.
SNC Response Figure 1 in Appendix 2 defines the examination volume for the acceptance examination of the overlay and, as discussed, it does not require examination of volume below the overlay.
However, a preservice examination will be performed in conjunction with the acceptance examination. The preservice examination volume shown in Figure 2 of Appendix 2 shows that the overlay and the upper 25% of the base material will be examined out to 1/2 from the edge of the weld. SNC considers Figure 2 to be a minimum coverage requirement and will examine the entire length of overlay and the upper 25% of the base metal, to the extent practical.
NRC Question 5 Item (g)(2) of the ASME Code,Section XI, Code Case N-504-2 requires that for repair welds the evaluation shall consider residual stresses produced by the structural overlay with other loads applied on the system. The effects of water backing on the repair weld shall be considered. The evaluation shall demonstrate that the requirements of IWB-3640 of the ASME Code,Section XI, 2001 Edition with Addenda through 2003 are satisfied.
Consistent with this requirement, the licensee should make a statement in its Relief Request that it will consider the effect of water backing in the evaluation for the structural overlay on the CRD return nozzle N9.
SNC Response SNC will consider the effect of water backing in the evaluation for the structural overlay on the CRD return nozzle N9. An evaluation will be submitted to the NRC within 90 days after plant startup.