OAK HARBOR, Ohio - Federal regulators have turned down a request to allow a third-party team of experts to look into reactor head damage at the Davis-Besse nuclear plant.

Citizen groups had asked the Nuclear Regulatory Commission for an outside review. Sam Collins, NRC nuclear reactor regulation director, formally rejected the request last week.

Viktoria Mitlyng, an NRC spokeswoman, said the request was denied because issues that were raised are being addressed by NRC investigators.

The decision did not surprise those who helped submit the petition, said Paul Gunter, of the Nuclear Information and Resource Service in Washington, D.C.

A boric acid leak at the Davis-Besse plant found in March was the most extensive corrosion ever on a U.S. nuclear reactor and led to a nationwide review of all 69 similar plants. A second, smaller hole was found later at Davis-Besse.

The plant near Toledo has been shut down since the corrosion was spotted.