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After close call, nuclear plants must make checks

Nuclear reactor operators have been ordered to check their reactor vessels after the discovery that acid in cooling water had eaten a hole nearly all the way through the 6-inch-thick lid of a reactor at a plant in Ohio. The corrosion left only a stainless-steel liner less than a half-inch thick to hold in cooling water under more than 2,200 pounds of pressure.

At the Ohio plant, Davis-Besse, near Toledo, the stainless steel was bent by the pressure and would have broken if corrosion had continued, according to the Nuclear Regulatory Commission, where officials were surprised by the discovery.

The commission, which has warned plants for years to watch for this kind of corrosion, has ordered all 68 other plants of similar design _ pressurized-water reactors _ to check their lids. The commission is particularly worried about a dozen of the oldest plants and ordered them to report by early April on whether they are safe enough to keep in service. The commission told these plants to demonstrate that technicians there would have noticed such corrosion in their normal inspections, had it occurred.

If the liner had given way in the Ohio reactor, experts say, there would have been an immediate release of thousands of gallons of slightly radioactive and extremely hot water inside the reactor's containment building.