To: stan_hughes who wrote (8743 ) 3/22/2002 11:58:26 PM From: russet Read Replies (1) | Respond to of 24920 US nuclear plants face downtime for reactor cracks -------------------------------------------------------------------------------- Mail this story to a friend | Printer friendly version USA: December 12, 2001 SAN FRANCISCO - The U.S. Nuclear Regulatory Commission has identified 13 atomic reactors that are developing tiny cracks that could seriously damage plant equipment and cause lengthy shutdowns for repairs. The NRC, which licenses and oversees the nation's fleet of 103 nuclear plants, doesn't believe the cracks in gear that controls the rate of atomic fission in the reactors could release poisonous radiation into the atmosphere, said Victor Dricks, a spokesman for the NRC. Instead, the chief headache is an economic one for the plant owners because complex inspections and repairs could idle a reactor - and shut off sales of electricity - for weeks, according to utility officials. Nuclear plants produce about one-fith of the nation's electricity. The hairline cracks in the reactor heads are believed to be caused by stress and corrosion triggered by high temperatures and pressure inside the reactors combined with years of producing electricity, according to the NRC. Akron, Ohio-based FirstEnergy Corp.'s 935-megawatt Davis Besse nuclear plant in Ohio was one of the 13 units the NRC identified as having the cracks or being "highly susceptible" to them, said Dricks. The plant was scheduled to shut in April for refueling and maintenance work, but the work was moved up to February at the NRC's request. Richard Wilkins, a spokesman for FirstEnergy Nuclear Operations, said the company hoped to complete the work in 35 to 40 days. CRACKS IN REACTOR NOZZLES The NRC investigation focused on metal alloy nozzles on 69 pressurized water reactors. Equipment known as control rods pass through the nozzles atop the "head" of the reactor. By raising or lowering rods of neatly stacked cylindrical uranium pellets, the control rods regulate the intensity of the atomic reaction taking place inside the reactor core. Pressurized water reactors typically have from 50 to 100 nozzles atop each reactor head. Cracks have appeared in the past along the length of the nozzles, but the NRC did not consider they needed immediate attention. Inspections and repairs usually were made during routine maintenance outages. Earlier this year, however, circular cracks around the nozzle width began to show up, raising a "potentially significant" safety concern, the NRC said in a bulletin sent to plant operators in August. Circular cracks are difficult to find, and plants may need to do inspections with the help of fiber optic cameras to pinpoint all of them, according to the NRC. The regulators' main worry is that a nozzle with circular cracks could separate from the reactor head, causing debris to fall into the fuel core and rupture cooling tubes and damage other power equipment, in turn allowing water to escape from the main plant cooling system. "It's like a leak in your car radiator. The system is under high pressure, so a break will cause coolant to leak out. You have to shut down the plant to find out what's going on," said a utility official. Exelon Nuclear's 786-megawatt Three Mile Island 1 unit in Pennsylvania, one of the 13 plants, had to extend a refueling outage expected to be finished in mid-November by about three weeks for more work, inspection and tests on the nozzles and two steam generators. Three Mile Island owner AmerGen Energy is a joint venture between Exelon Corp. , of Chicago, and British Energy Plc of Scotland. The NRC's list also includes Virginia Power Co.'s 800-megawattt Surry 1 and 921-megawatt North Anna 2 plants in Virginia. Virginia Power, a unit of Richmond, Virginia-based Dominion , is making the repairs, Dricks said. Story by Leonard Anderson REUTERS NEWS SERVICE