Views of reactor head obstructed in many plant inspections

The Associated Press
4/1/02 12:02 AM

TOLEDO, Ohio (AP) -- Inspectors at most nuclear power plants similar to the temporarily closed Davis-Besse do not get a complete look at reactor heads, according to an industry report that has been turned over to the Nuclear Regulatory Commission.

At least 40 of the 69 nuclear plants with pressurized-water reactors said their most recent visual inspections were completed without removing obstacles such as insulation, or without inspectors getting into position to see everything, The Blade reported Saturday.

Some utilities said their reactors stand so tall and the devices implanted in reactor heads are packed so tightly that obstacle-free inspection is almost impossible.

The informal survey was conducted by the Washington-based Nuclear Energy Institute, an industry trade group.

FirstEnergy Corp. of Akron has shut down the Davis-Besse Nuclear Power Station near Port Clinton, a pressurized-water plant, because of corrosion in its reactor head, apparently caused by boric acid deposits. It plans to have the plant bak on line by June.

The corrosion has been described as the most severe ever found in a nuclear plant in the United States.

The company found a 4-inch by 5-inch by 6 1/2-inch deep hole in the reactor's 17-foot-wide steel cap. In some parts of the cap, the stainless steel was thinned to less than one-half inch.

The plant had visual inspections over the years, but corrosion was overlooked.

FirstEnergy recently acknowledged about 15 percent of the plant's reactor head is typically out of sight because of heavy insulation.

At other plants surveyed, obstructions were noted in as little as 2 percent to as much as 40 percent of the viewing area.

The industry report did not indicate any worse corrosion elsewhere, although several plants acknowledged having acid leakage that the industry considers minor, the newspaper said.

The NRC considers the industry report to be "additional information that the staff will look at and evaluate," but it will not vouch for the report's results or use them in deciding its next move, NRC spokesman Victor Dricks said.

It is awaiting technical responses to a bulletin it issued earlier this month to all nuclear plants with pressurized-water reactors.

Those responses are due Tuesday, Dricks said.

The nation has 103 operating nuclear plants, of which 69 have pressurized water reactors. The rest, including FirstEnergy's Perry plant east of Cleveland, have boiling-water reactors, which the utility says are not susceptible to the corrosion problem because they don't use acid.