ML100770249
| ML100770249 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 03/26/2010 |
| From: | Orf T Plant Licensing Branch II |
| To: | Mccartney E Carolina Power & Light Co |
| Orf, T J, NRR/DORL/301-415-2788 | |
| References | |
| TAC ME0233 | |
| Download: ML100770249 (4) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 March 26, 2010 Mr. Eric McCartney, Vice President Carolina Power & Light Company H. B. Robinson Steam Electric Plant, Unit NO.2 3581 West Entrance Road Hartsville, South Carolina 29550 SLlB..IECT:
H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING REVIEW OF REFUELING OUTAGE 25 INSPECTIONS OF THE REACTOR VESSEL NOZZLE DISSIMILAR METAL BUTT WELDS (TAC NO. ME0233)
Dear Mr. McCartney:
By letter dated December 8,2008, Carolina Power & Light Company (the licensee), now doing business as Progress Energy Carolinas, Inc., submitted to the Nuclear Regulatory Commission the results of inspections conducted during refueling outage 25 on dissimilar metal butt welds in the reactor vessel nozzles. The licensee also provided supplemental information by letters dated January 21, 2009, and January 18, 2010.
In order for the staff to complete its review of the information provided, we request that the licensee provide responses to the enclosed request for additional information (RAI). Based on discussions with your staff, we understand that you plan to respond to the enclosed RAI within 90 days of the date of this letter.
If you have any questions about this material, please contact me at (301) 415-2788.
Sincerely, Tracy J. Orf, roject Manager Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-261
Enclosure:
Request for Additional Information cc: Distribution via Listserv
REQUEST FOR ADDITIONAL INFORMATION INSPECTIONS OF THE REACTOR VESSEL NOZZLE DISSIMILAR METAL BUTT WELDS DURING REFUELING OUTAGE 25 H.B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO.2 CAROLINA POWER & LIGHT COMPANY DOCKET NO. 50-261 By letter dated December 8,2008, Carolina Power & Light Company (the licensee), now doing business as Progress Energy Carolinas, Inc., submitted to the NRC the results of inspections conducted on dissimilar metal butt welds in the hot and cold leg nozzles attached to the reactor vessel. By letter dated January 21, 2009, the licensee submitted, based on the NRC's request, the Westinghouse proprietary report WCAP-15620-P, Revision 1, "Background and Technical basis: Handbook on Flaw Evaluation for the H.B. Robinson Unit 2 Reactor Vessel." By letter dated January 18, 2010, the licensee responded to the staff's request for additional information.
Based on staff review of the response and the staff's independent analysis of the existing flaws in the hot and cold leg, the staff requests the following additional information. The staff discussed the following questions with the licensee in a teleconference held on March 8, 2010.
- 1. Provide the as-built information (or design if the as-built information is not available) regarding the width (axial length) of the safe-ends and Alloy 82/182 dissimilar metal welds (DMW) in the hot and cold leg nozzles. Provide the as-built (or design) distance between the center line of the safe end-to-pipe weld and the center line of the DMW for the hot and cold legs.
- 2. The December 8, 2008 letter, Attachment, page 4, states that the hot leg nozzles were not buttered before welding to the safe ends. The staff would like to understand the fabrication details of the hot and cold leg nozzles.
- a. Describe the fabrication process for the hot and cold leg nozzles, including welding of the DMW, safe-end, and the associated pipe. Discuss the heat treatment of the hot leg and cold leg nozzles including the safe-ends (i.e., were the safe-ends heat treated?). How many hours were the nozzles heat treated and at what temperature.
- b. Discuss whether the safe-ends were fabricated with wrought or cast stainless steel.
- c. Confirm that the cold leg nozzle was buttered and stress relieved prior to the DMW fabrication.
- 3. Discuss the inspection results of the examinations performed in 2008, including any eddy current surface examinations conducted.
- a. Discuss the locations and number of indications.
- b. Confirm the axial flaws are located in the safe-end base material, not in the interface between the safe-end and DMW or between the safe-end and cladding. The staff
- 2 understands that five circumferential flaws are wholly contained in clad material. The staff assumes that only the vessel nozzles are cladded and that DMW and safe-end are not cladded.
- c.
Discuss the location of these five circumferential flaws in cladding with respect to the DMW. Based on the nozzle configuration drawings on Page 3 of the attachment to the December 8, 2008 letter, the DMW is in contact with the stainless steel nozzle cladding. Therefore, discuss whether a circumferential flaw is located in the interface between the DMW and cladding.
- d. Confirm that none of indications detected is connected to the inside surface of the pipe.
- e. Discuss whether ultrasonic testing inspection of the hot and cold leg was performed from the outside diameter or inside diameter surface of the pipe during refueling outage 25 in the fall of 2008.
- 4. The licensee accepted some of the flaws for continued service based on analysis in accordance with IWB-3600 of the ASME Code,Section XI. IWB-2420 of the ASME Code,Section XI requires three successive examinations of the flaws remaining in service.
- a. Provide the schedule (approximate month and year and refueling outage number) for the three successive examinations.
- b. Discuss inspection plans (nondestructive examination techniques and the components) for the 2010 refueling outage and 2011 refueling outage.
- Via E-mail OFFICE LPL2-2/PM LPL2-2/LA CPNB/BC LPL2-2/BC (A)
NAME TOrf RSoia TLupold*
DBroaddus (BMozafari for)
DATE 03/18/10 03/18/10 03/11/10 03/26/10