NRC: News Release - Region III - 2002-002 - NRC to Conduct Augmented Inspection Of Davis-Besse Reactor Vessel Damage

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U.S. NUCLEAR REGULATORY COMMISSION

Office of Public Affairs, Region III
2443 Warrenville Road, Lisle, IL 60532
www.nrc.gov

No. III-02-002		March 12, 2002
CONTACT:	Jan Strasma (630) 829-9663	E-mail: OPA3.RegionIII@nrc.gov
NRC TO CONDUCT AUGMENTED INSPECTION OF DAVIS-BESSE REACTOR VESSEL DAMAGE Printable Version
The Nuclear Regulatory Commission has begun a Augmented Team Inspection into damage to a small area of the top of the reactor vessel, apparently caused by corrosion, at the Davis-Besse Nuclear Power Station. The plant, located at Oak Harbor, Ohio, is operated by FirstEnergy Corporation. The plant has been shut down since February 16 for refueling and maintenance. The cavity in the top of the reactor vessel was discovered during inspection and repair activities in the outage. It is about 4 inches by 5 inches and approximately 6 inches deep. The reactor vessel head, fabricated of carbon steel with a stainless steel liner, is about 6 1/2 inches thick. During the outage, plant personnel inspected 69 control rod tubes which pass through the reactor vessel head. The NRC issued a bulletin last August requiring the detailed inspections at Davis-Besse and other sites after cracking problems were found at several other nuclear plants. Using ultrasonic techniques, FirstEnergy workers found cracks through the tube walls in three tubes, and lesser cracks in two additional tubes. During repairs to one of the tubes with through-wall cracks, workers discovered the void adjacent to the tube. The NRC's Augmented Inspection Team, comprised of metallurgical and engineering specialists, will monitor the utility's investigation and evaluation of the cavity and its determination of the conditions causing the damage. The inspection is being conducted to better understand the circumstances surrounding the corrosion and damage and to consider whether similar conditions might exist at other plants. The preliminary cause of the damage appears to be corrosion as a result of boric acid deposits. Boric acid is a constituent of the water in the reactor cooling system and was apparently deposited on the reactor vessel through the leaking crack in the control rod tube or some other source. The utility is developing its plans for repair of the reactor vessel head. The NRC will review the utility's plans. Following completion of the inspection, the NRC will hold a meeting in the plant vicinity to discuss the inspection findings. The meeting will be open to public observation. The inspection report, issued about four weeks after the inspection, will be available on the agency's website and through its Electronic Reading Room at http://www.nrc.gov as an Agencywide Document Access and Management System (ADAMS) document. Help in using ADAMS is available through the NRC Public Document Room at 301/415-4737 or 800/397-4209. The NRC has issued an Information Notice to operating nuclear plants to inform them of the corrosion damage at Davis-Besse. The notice will be available online in the Electronic Reading Room with the accession number of ML020700556.
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