Beacon Journal business writer

A key emergency system designed to prevent a meltdown at FirstEnergy's Davis-Besse nuclear plant was so seriously flawed that the Nuclear Regulatory Commission on Thursday said it plans to give it the agency's second-worst safety rating.

The emergency system, with a decades-old 50-square-foot sump area designed to recirculate water back into the reactor during what is called a loss of coolant accident, has been replaced with an improved version. The old sump was too small and susceptible to clogging from debris that likely would be created from such an accident, the NRC said.

FirstEnergy discovered and disclosed the problem last year. It has since spent millions of dollars to design and build a 1,200-square-foot sump area at the troubled nuclear plant in Oak Harbor, and also removed potential sources of debris inside the containment chamber that surrounds the reactor. The plant has been shut down since mid February 2002.

The NRC said it is proposing to give the old sump a ``yellow'' rating under its color-coded safety assessment system. A green rating is given for findings of minor safety significance, then white, yellow and finally red for a finding of high safety significance. The sump problem was highlighted in a 42-page NRC inspection report that found other, less significant safety problems at the plant.

Typically, a yellow finding could lead to increased NRC inspections and oversight, but the agency said the plant is already receiving extra federal monitoring.

FirstEnergy will not contest the preliminary yellow assessment, utility spokesman Todd Schneider said.

``We identified the problem and we took decisive steps to remove the old sump,'' he said. ``We have resolved that issue.''

FirstEnergy hopes to have Davis-Besse ready to restart this fall, with total repair and replacement power costs to exceed $500 million. The company said the most significant issue to be resolved is to modify high pressure injection pumps to make them less likely to clog during an accident.

``The major stuff seems to be pretty well wrapped up,'' Schneider said. The NRC has final say on when Davis-Besse will be allowed to restart.

Because of the problems found with Davis-Besse's old sump system, the NRC earlier this year ordered the operators of the 68 other similar reactors in the nation to review their sumps as well.

In 2001, the NRC listed Davis-Besse as among the top five least likely of the 69 pressurized water reactor plants in the nation to be vulnerable to sump problems, said David Lochbaum, nuclear expert with the Union of Concerned Scientists.

This latest yellow assessment means Davis-Besse is the only nuclear power plant in the country to have received all four color safety assessments, Lochbaum said. The NRC gave Davis-Besse a ``red'' assessment for the large corrosion hole found last year nearly all the way through the top of the reactor's former steel vessel head.

The NRC inspection report also noted that Davis-Besse control room operators ignored three alarms showing that a turbine room was being flooded with water during a test in May. About three inches of water accumulated in the turbine room before it was discovered by another worker and reported. The NRC gave the incident a ``green'' safety assessment rating.

Lochbaum said while he thought the flooding was not a big deal, he found it troubling that it happened, especially because the plant is under so much scrutiny.

Schneider said the control room operators have been talked to, and that no disciplinary measures were taken.