Ohio nuclear plant corrosion raises concerns, says NRC
Wednesday, March 20, 2002
By Reuters
http://enn.com/news/wire-stories/2002/03/03202002/reu_46715.aspWASHINGTON - U.S. regulators Tuesday ordered 69 nuclear plants to submit reactor safety information after finding unexpected corrosion at an Ohio plant owned by FirstEnergy Corp. that raised broader concerns.
FirstEnergy last month shut its Davis-Besse nuclear power plant in Oak Harbor, Ohio, due to corrosion inside the reactor chamber.
The Nuclear Regulatory Commission (NRC) wrote to 69 U.S. plants with pressurized water reactors similar to Davis-Besse's seeking information on their structural integrity. The agency said it did not believe the problems at the Ohio plant could release radiation into the atmosphere but that they could reduce its margin of safety.
The other 34 reactors, which use boiling water reactors, were not required to take any action. There are 103 total operating U.S. nuclear power plants, which generate about 20 percent U.S. electricity supplies.
Regulators gave the utilities two weeks to respond, a short turnaround that "reflects the seriousness with which we view this," an NRC spokesman said.
While refueling the Ohio plant in February, FirstEnergy found an area on top of a high-pressure vessel which contains the nuclear reaction that showed unusual wear. Corrosion left less than one-quarter inch of stainless steel to protect the top of the reactor vessel, normally shielded by 6.5 inches of carbon steel, the NRC spokesman said.
The NRC said it expects that a corrosive coolant leaking from the reactor core ate through the pressure vessel but has not announced definite findings. "The issue could have generic implications for other pressurized water reactors," the spokesman said.
The NRC said it will use the new information to determine if its current inspection and maintenance practices are adequate.
FirstEnergy's 925-megawatt plant supplies electricity to the Midwest electricity grid.
NRC inspections now underway at Davis-Besse show boric acid in the cooling water was a contributing cause of corrosion. Boric acid is added to the water to control the speed of the nuclear reaction.
Last year, the NRC identified 13 reactors that either developed or were believed highly susceptible to developing tiny cracks that could damage power plant equipment and cause lengthy shutdowns for repairs. Of the 13 units, cracks were found and repairs were made at three. Eight did not show cracks.
Two plants - the Davis-Besse plant and American Electric Power's Cook 2 unit in Michigan - were to be inspected. Repairs were made at the 1,090-megawatt Cook 2 reactor earlier this year.