The estimated cost of repairs this year for the troubled Davis-Besse nuclear power plant has jumped by about 60 percent to $80 million, while a hoped-for restart has been pushed back into the fall, owner FirstEnergy Corp. said Thursday.

The higher repair bill, coupled with the need to buy replacement power into the fall, is likely to hike total costs to more than $500 million before the 883-megawatt plant will be allowed to restart.

The Akron utility previously estimated it would spend about $50 million on repairs this year for the shut-down Oak Harbor plant. But needed modifications to safety equipment, including high-pressure injection pumps, have increased costs and pushed back previous restart dates this year, FirstEnergy said.

As a result, Davis-Besse, in Oak Harbor about 25 miles east of Toledo, will not be ready to restart any sooner than this fall, the company said. The company earlier this week said the plant probably would not be ready to restart any sooner than mid-September. The Nuclear Regulatory Commission has final say on when the plant can restart.

FirstEnergy has reported it spent about $300 million in repairs and to buy replacement power for Davis-Besse after unprecedented boric acid damage that went nearly all the way through the top of the reactor vessel was found in March 2002.

Through June 30, FirstEnergy reported it spent $58 million in repairs this year. It also spent approximately $15 million a month through June to buy replacement power. The utility expects to pay between $20 million and $25 million in July and August to buy electricity.

Including the revised $80 million repair figure, but not including July and August electricity purchases, total costs are now $473 million.