ML042020262
| ML042020262 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 07/27/2004 |
| From: | Dick G NRC/NRR/DLPM/LPD3 |
| To: | Crane C Exelon Generation Co |
| Dick G F, NRR/DLPM, 415-3019 | |
| References | |
| TAC MC1894 | |
| Download: ML042020262 (6) | |
Text
July 27, 2004 Mr. Christopher M. Crane, President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
EVALUATION OF STEAM GENERATOR INSERVICE INSPECTION
SUMMARY
REPORT, BRAIDWOOD, UNIT 1 (TAC NO. MC1894)
Dear Mr. Crane:
By letters dated May 7, 2003 (ML031360617), July 29, 2003 (ML032190155), July 31, 2003 (ML032170925), and April 16, 2004 (ML041140380) Exelon Generation Company, LLC (Exelon) submitted reports summarizing the steam generator tube inspections performed during the tenth refueling outage (April 2003) at Braidwood Station, Unit 1. Additional information pertaining to the 2003 steam generator tube inspections was summarized by the NRC staff in a telephone conference call summary dated June 18, 2003 (ML031570110).
As discussed in the enclosed evaluation, the staff concludes that Exelon provided the information required by their technical specifications. In addition, the NRC staff did not identify any technical issues that warranted follow up action at this time. The staff did note, however, that 132 tubes were classified as having tube-to-tube contact. Exelon indicated that it would continue to monitor the condition and perform inspections of the affected tubes during each scheduled steam generator inspection. The staff believes that continued monitoring is important especially if a new mechanism (i.e., not related to fabrication) is causing tube-to-tube contact since a new mechanism may result in different wear/corrosion rates than assumed in the original tube integrity analysis.
Please contact me if you have questions.
Sincerely,
/RA/
George F. Dick, Jr., Project Manager, Section 2 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation
July 27, 2004 Mr. Christopher M. Crane, President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
EVALUATION OF STEAM GENERATOR INSERVICE INSPECTION
SUMMARY
REPORT, BRAIDWOOD, UNIT 1 (TAC NO. MC1894)
Dear Mr. Crane:
By letters dated May 7, 2003 (ML031360617), July 29, 2003 (ML032190155), July 31, 2003 (ML032170925), and April 16, 2004 (ML041140380) Exelon Generation Company, LLC (Exelon) submitted reports summarizing the steam generator tube inspections performed during the tenth refueling outage (April 2003) at Braidwood Station, Unit 1. Additional information pertaining to the 2003 steam generator tube inspections was summarized by the NRC staff in a telephone conference call summary dated June 18, 2003 (ML031570110).
As discussed in the enclosed evaluation, the staff concludes that Exelon provided the information required by their technical specifications. In addition, the NRC staff did not identify any technical issues that warranted follow up action at this time. The staff did note, however, that 132 tubes were classified as having tube-to-tube contact. Exelon indicated that it would continue to monitor the condition and perform inspections of the affected tubes during each scheduled steam generator inspection. The staff believes that continued monitoring is important especially if a new mechanism (i.e., not related to fabrication) is causing tube-to-tube contact since a new mechanism may result in different wear/corrosion rates than assumed in the original tube integrity analysis.
Please contact me if you have questions.
Sincerely,
/RA/
George F. Dick, Jr., Project Manager, Section 2 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation DISTRIBUTION:
PUBLIC PDIII-2 R/F AMendiola PCoates GDick OGC ACRS KKarwoski LLund MMurphy EMurphy SReynolds, RIII AStone, RIII ADAMS Accession Number: ML042020262 OFFICE PM:PDIII-2 LA:PDIII-2 SC:PDIII-2 NAME GDick PCoates AMendiola DATE 07/22/04 7/22/04 7/27/04 OFFICIAL RECORD COPY
Braidwood Station Units 1 and 2 cc:
Regional Administrator, Region III U.S. Nuclear Regulatory Commission 801 Warrenville Road Lisle, IL 60532-4351 Document Control Desk - Licensing Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Ms. C. Sue Hauser, Project Manager Westinghouse Electric Corporation Energy Systems Business Unit Post Office Box 355 Pittsburgh, PA 15230 Joseph Gallo Gallo & Ross 1025 Connecticut Ave., NW, Suite 1014 Washington, DC 20036 Ms. Bridget Little Rorem Appleseed Coordinator 117 N. Linden Street Essex, IL 60935 Howard A. Learner Environmental Law and Policy Center of the Midwest 35 East Wacker Dr., Suite 1300 Chicago, IL 60601-2110 U.S. Nuclear Regulatory Commission Braidwood Resident Inspectors Office 35100 S. Rt. 53, Suite 79 Braceville, IL 60407 Ms. Lorraine Creek RR 1, Box 182 Manteno, IL 60950 Illinois Emergency Management Agency Division of Disaster Assistance &
Preparedness 110 East Adams Street Springfield, IL 62701-1109 Chairman Will County Board of Supervisors Will County Board Courthouse Joliet, IL 60434 Attorney General 500 S. Second Street Springfield, IL 62701 George L. Edgar Morgan, Lewis and Bockius 1111 Pennsylvania Ave, NW Washington, DC 20004 Braidwood Station Plant Manager Exelon Generation Company, LLC 35100 S. Rt. 53, Suite 84 Braceville, IL 60407-9619 Site Vice President - Braidwood Exelon Generation Company, LLC 35100 S. Rt. 53, Suite 84 Braceville, IL 60407-9619 Senior Vice President, Nuclear Services Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Vice President of Operations - Mid-West Pressurized Water Reactors Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Chairman, Ogle County Board Post Office Box 357 Oregon, IL 61061
Braidwood Station Units 1 and 2 Regulatory Assurance Manager - Braidwood Exelon Generation Company, LLC 35100 S. Rt. 53, Suite 84 Braceville, IL 60407-9619 Director - Licensing and Regulatory Affairs Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Associate General Counsel Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Vice President - Licensing and Regulatory Affairs Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Manager Licensing - Braidwood, Byron and LaSalle Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE EVALUATION OF TENTH REFUELING OUTAGE STEAM GENERATOR TUBE INSPECTION RESULTS EXELON GENERATION COMPANY, LLC BRAIDWOOD STATION, UNIT 1 DOCKET NO. STN 50-456 By letters dated May 7, 2003 (ML031360617), July 29, 2003 (ML032190155), July 31, 2003 (ML032170925), and April 16, 2004 (ML041140380), Exelon Generation Company, LLC ( the licensee) submitted reports summarizing the steam generator tube inspections performed during the tenth refueling outage (April 2003) at Braidwood Station, Unit 1. Additional information pertaining to the 2003 steam generator tube inspections was summarized by the Nuclear Regulatory Commission staff in a telephone conference call summary dated June 18, 2003 (ML031570110).
The four steam generators at Braidwood, Unit 1 were replaced in 1998 with steam generators fabricated by Babcock and Wilcox International. Each steam generator contains 6633 thermally treated Alloy 690 tubes. Each tube has a nominal outside diameter of 0.6875-inch and a nominal wall thickness of 0.040-inch. The tubes were hydraulically expanded at both ends for the full length of the tubesheet and are supported by a number of stainless steel tube supports (lattice grid). The tubes installed in rows 1 through 21 were thermally stress relieved after bending.
The scope and results of the licensees inspections are contained in the documents referenced above. Based on a review of the above documents, the staff concludes that the licensee provided the information required by their technical specifications. In addition, the staff did not identify any technical issues that warranted follow-up action at this time; however, the staff did have the following observation regarding the results of the licensees inspection and assessments.
During fabrication of the steam generators, tube-to-tube contact was identified. This condition was expected to naturally correct itself after one or two cycles of operation in the vertical position (licensees license amendment application of February 9, 2001, ML010470080). During the preservice inspection, 508 tubes were identified as being in contact. The number of tubes in contact dropped to 85 when examined during the 2000 outage. Reinspection of these 85 tubes during the 2003 outage showed 67 remained in contact; however, 65 additional tubes, which had not been in contact in the past, were classified as being in contact during the 2003 outage. The licensee previously assessed tube integrity given the tube-to-tube contact condition and concluded that there were no structural integrity concerns for the life of the steam generators. In addition, the licensee indicating they would continue to monitor the condition and perform inspections of the affected tubes during each scheduled steam generator inspection. The staff notes that continued monitoring is important especially if a new mechanism (i.e., not related to fabrication) is causing tube-to-tube contact since a new mechanism may result in different wear/corrosion rates than assumed in the original tube integrity analysis.
Principal Contributor: K. Karwoski Date: July 27, 2004