ML081900418
| ML081900418 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 07/17/2008 |
| From: | Goodwin C NRC/NRR/ADRO/DORL/LPLIII-2 |
| To: | Allen B FirstEnergy Nuclear Operating Co |
| Goodwin C | |
| References | |
| TAC MD8065 | |
| Download: ML081900418 (5) | |
Text
July 17, 2008 Mr. Barry S. Allen Site Vice President FirstEnergy Nuclear Operating Company Davis-Besse Nuclear Power Station Mail Stop A-DB-3080 5501 North State Route 2 Oak Harbor, OH 43449-9760
SUBJECT:
DAVIS-BESSE NUCLEAR POWER STATION, UNIT NO. 1 -
SUMMARY
OF VOLUMETRIC EXAMINATION OF WELD OVERLAYS OF DISSIMILAR METAL WELDS OF PRESSURIZER AND HOT-LEG NOZZLES (TAC NO. MD8065)
Dear Mr. Allen:
By letter to the Nuclear Regulatory Commission (NRC) dated February 15, 2007, as supplemented by letters dated June 28, September 28, and November 19, 2007, FirstEnergy Nuclear Operating Company submitted Relief Request (RR)-A30, Revision 2, as an alternative to American Society of Mechanical Engineers Code,Section XI requirements in support of weld overlay repairs, for the Davis-Besse Nuclear Power Station, Unit No. 1. RR-A30, Revision 2, provides weld overlays of dissimilar metal welds of pressurizer nozzles, hot-leg decay heat line nozzle, and hot-leg surge line nozzle. By letter dated December 20, 2007, the NRC authorized RR-A30, Revision 2, for the weld overlay repairs.
In RR-A30, Revision 2, the licensee committed to submit the final ultrasonic examination results of the weld overlays within 14 days of the completion of the examination. The final ultrasonic examination was performed on January 22, 2008. By letter dated February 5, 2008, the licensee submitted the results of its weld overlay ultrasonic examination. Enclosed is the NRC staffs summary of the subject examination.
Sincerely,
/RA/
Cameron S. Goodwin, Project Manager Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-346
Enclosure:
Summary of Ultrasonic Weld Overlay Examination cc w/encl: See next page
Davis-Besse Nuclear Power Station, Unit No. 1 cc:
Corporate Distribution The Honorable Dennis J. Kucinich FirstEnergy Nuclear Operating Company United States House of Representatives Via e-mail Washington, D.C. 20515 Davis-Besse Distribution The Honorable Dennis J. Kucinich FirstEnergy Nuclear Operating Company United States House of Representatives Via e-mail 14400 Detroit Avenue Lakewood, OH 44107 Ohio Department of Commerce Division of Industrial Compliance Via e-mail Resident Inspector U.S. Nuclear Regulatory Commission Via e-mail Stephen Helmer, Supervisor Bureau of Radiation Protection Via e-mail Carol OClaire, Chief, Radiological Branch Ohio Emergency Management Agency Via e-mail Daniel Z. Fisher, Transportation Department Public Utilities Commission Via e-mail Zack A. Clayton DERR Ohio Environmental Protection Agency Via e-mail Principal Assistant Attorney General Environmental Enforcement Section State Office Tower 30 East Broad Street 25th Floor Columbus, OH 43215 President, Board of County Commissioners of Ottawa County Via e-mail President, Board of County Commissioners of Lucas County One Government Center, Suite 800 Toledo, OH 43604-6506
July 17, 2008 Mr. Barry S. Allen Site Vice President FirstEnergy Nuclear Operating Company Davis-Besse Nuclear Power Station Mail Stop A-DB-3080 5501 North State Route 2 Oak Harbor, OH 43449-9760
SUBJECT:
DAVIS-BESSE NUCLEAR POWER STATION, UNIT NO. 1 -
SUMMARY
OF VOLUMETRIC EXAMINATION OF WELD OVERLAYS OF DISSIMILAR METAL WELDS OF PRESSURIZER AND HOT-LEG NOZZLES (TAC NO. MD8065)
Dear Mr. Allen:
By letter to the Nuclear Regulatory Commission (NRC) dated February 15, 2007, as supplemented by letters dated June 28, September 28, and November 19, 2007, FirstEnergy Nuclear Operating Company submitted Relief Request (RR)-A30, Revision 2, as an alternative to American Society of Mechanical Engineers Code,Section XI requirements in support of weld overlay repairs, for the Davis-Besse Nuclear Power Station, Unit No. 1. RR-A30, Revision 2, provides weld overlays of dissimilar metal welds of pressurizer nozzles, hot-leg decay heat line nozzle, and hot-leg surge line nozzle. By letter dated December 20, 2007, the NRC authorized RR-A30, Revision 2, for the weld overlay repairs.
In RR-A30, Revision 2, the licensee committed to submit the final ultrasonic examination results of the weld overlays within 14 days of the completion of the examination. The final ultrasonic examination was performed on January 22, 2008. By letter dated February 5, 2008, the licensee submitted the results of its weld overlay ultrasonic examination. Enclosed is the NRC staffs summary of the subject examination.
Sincerely,
/RA/
Cameron S. Goodwin, Project Manager Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-346
Enclosure:
Summary of Ultrasonic Weld Overlay Examination cc w/encl: See next page DISTRIBUTION:
PUBLIC LPL3-2 R/F RidsNrrDorlLpl3-2 RidsNrrPMCGoodwin RidsNrrLATHarris RidsAcrsAcnw&mMailCenter RidsOgcRp RidsRgn3MailCenter RidsNrrDorlDpr ADAMS Accession Number: ML081900418 OFFICE LPL3-2/PM LPL3-2/LA LPL3-2/BC NAME CGoodwin THarris RGibbs (CGratton for)
DATE 7/17/08 7/17/08 7/17/08 OFFICIAL RECORD COPY
SUMMARY
OF THE ULTRASONIC EXAMINATION OF WELD OVERLAYS FOR DISSIMILAR METAL WELDS OF PRESSURIZER NOZZLES HOT-LEG DECAY HEAT AND SURGE NOZZLES DAVIS-BESSE NUCLEAR POWER STATION, UNIT NO. 1 DOCKET NO. 50-346
1.0 INTRODUCTION
By letter dated February 15, 2007 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML071020195), as supplemented by letters dated June 28 (ADAMS Accession No. ML071840039), September 28 (ADAMS Accession No. ML072750034), and November 19, 2007 (ADAMS Accession No. ML073040095), the FirstEnergy Nuclear Operating Company (the licensee) requested Nuclear Regulatory Commission (NRC) approval of Relief Request (RR)-A30, Revision 2, as an alternative to American Society of Mechanical Engineers (ASME) Code,Section XI requirements in support of weld overlay repairs for the Davis-Besse Nuclear Power Station, Unit No. 1 (DBNPS). RR-A30, Revision 2, provides weld overlays of dissimilar metal welds of pressurizer nozzles, hot-leg decay heat line nozzle, and hot-leg surge line nozzle. By letter dated December 20, 2007 (ADAMS Accession No. ML073190511), the NRC authorized RR-A30, Revision 2, for the weld overlay repairs.
RR-A30, Revision 2, contains a commitment to submit within 14 days of the final ultrasonic examination for the weld overlays, information relevant to the indications and disposition of indications. The final ultrasonic examination was performed on January 22, 2008. By letter dated February 5, 2008 (ADAMS Accession No. ML080380331), the licensee submitted the results of its weld overlay ultrasonic examination. The licensees volumetric examination of the subject weld overlays is summarized below.
2.0 DISCUSSION The licensee examined the following welds using ultrasonic testing (UT):
Pressurizer Safety Nozzle Weld RC-PZR-WP-91-W/X Pressurizer Safety Nozzle Weld RC-PZR-WP-91-Y/Z Pressurizer Relief Nozzle Weld RC-PZR-WP-91-Z/W Pressurizer Spray Nozzle Weld RC-PZR-WP-102 Pressurizer Surge Nozzle Weld RC-PZR-WP-23 Hot-Leg Surge Nozzle Weld RC-MK-a-82-FW54 Hot-Leg Decay Heat Nozzle Weld DH-33A-CCA-4-1-FW1 The licensee used SI-UT-126, Revision 3, Procedure for the Phased Array Ultrasonic Examination of Weld Overlaid Similar and Dissimilar Metal Welds, to examine weld overlays.
This procedure, and the examiners who applied the procedure, are qualified through the ENCLOSURE
Performance Demonstration Initiative (PDI) program at the Electrical Power Research Institute Nondestructive Examination Center. The licensee did not detect any reportable indications exceeding the acceptance standards of the ASME Code,Section XI, Tables IWB-3514-1, IWB-3514-2, or IWB-3514-3, except for the hot-leg decay heat nozzle dissimilar metal weld DH-33A-CCA-4-1-FW1. The licensee achieved 100 percent examination coverage on all welds using SI-UT-126, Revision 3 procedure.
Per RR-A30 examination, the licensee detected one indication in the weld overlay of hot-leg decay heat nozzle weld DH-33A-CCA-4-1-FW1, which was characterized as a circumferential planer sub-surface indication in the weld overlay. This indication is outside the required inservice inspection (ISI) examination volume and is located between the 180 and 270 degree azimuth. This indication is acceptable in accordance with ASME Code,Section XI, Table IWB-3514-2, as characterized in accordance with IWA-3300. No other suspected planer or laminar flaw indications were observed within the weld overlay material.
In addition, while installing the overlay on weld, DH-33A-CCA-4-1-FW1, a blow hole occurred in the weld overlay which the licensee subsequently repaired. To better characterize the indication underneath the blow hole, the licensee performed augmented examination of weld DH-33A-CCA-4-1-FW1. The licensee used SI-UT-130, Revision 0, Procedure for the Phased Array Ultrasonic Examination of Dissimilar Metal Welds, to examine weld DH-33A-CCA-4 FW1. The NRC staff notes that this procedure is not qualified by the PDI program and this augmented examination is not required per the NRC-approved relief request RR-A30, Revision 2.
In the augmented examination, the licensee confirmed the flaw in weld DH-33A-CCA-4-1-FW1 that caused the blow hole was axial in nature. The axial flaw is located between the 90 and 180 degree azimuth at 14.5 inches long. The examination gain was adjusted to maintain the procedure-specified baseline noise level from 5 percent to 20 percent of full screen height. The lower range of examination angles detected responses from the inside surface of the component which were useful for monitoring search unit contact/coupling effectiveness during these examinations. No additional suspected flaw indications were observed within the ISI examination volume.