The Davis-Besse nuclear plant is getting less than glowing grades again from the Nuclear Regulatory Commission.

The federal agency has formally criticized the FirstEnergy-owned plant for letting five contract workers leave the plant while contaminated with small amounts of radioactive particles. The Akron utility will not be fined or otherwise penalized.

In related news, a watchdog group's investigation of the government's decision to keep Davis-Besse running found that political pressure played no role in delaying a shutdown of the reactor.

Regarding the radioactive particles, the NRC has determined that their accidental release about a year ago was of low to moderate importance to safety. The agency on Thursday released a letter sent to FirstEnergy making final its preliminary finding from about a month ago.

``These are important issues, issues that need to be corrected,'' NRC spokesman Jan Strasma said. The agency made those issues part of a checklist the Akron utility needs to complete in order to be allowed to restart the Oak Harbor plant.

FirstEnergy has corrected the problems and taken steps to prevent further accidental release of radioactive particles, a spokesman said. Davis-Besse has overhauled its radiation detection process, hired a manager for a new radiation protection department, bought new detection equipment and recalibrated existing equipment, FirstEnergy spokesman Todd Schneider said.

``There was no threat to the public safety,'' he said.

The workers, who had been working on the plant's steam generator, carried the microscopic radioactive particles to South Carolina, Texas, Virginia and elsewhere in Ohio.

The NRC has said the workers never should have been allowed out of the plant with the particles on them. While the workers received relatively low radiation dosages, the radiation levels probably exceeded the amount workers are allowed to be exposed to in one year's time, the NRC said.

Two of the workers ``potentially received a relatively large amount of internal contamination,'' the NRC concluded.

Also, the watchdog group Union of Concerned Scientists released documents this week that show an NRC decision to delay closing Davis-Besse beyond a Dec. 31, 2001, deadline was not influenced by politicians.

The NRC wanted to shut down the plant by that deadline, fearing possible cracks or leaks in the nozzles that pass through the reactor lid.

But FirstEnergy lobbied the agency for an extension and the NRC compromised, letting the plant run until mid-February 2002. Two weeks later workers found a hole in the reactor's lid from years of leaking boric acid.

The NRC's inspector general's office looked into whether the decision to delay the shutdown was swayed by politics, but no evidence of that was found, according to documents released Wednesday under the Freedom of Information Act.

The NRC's inspector general's office last year looked to see, among other things, whether Sen. George Voinovich tried to sway the NRC to let the plant on the Lake Erie shoreline east of Toledo keep operating.

Transcripts of interviews show investigators asked NRC, FirstEnergy and other officials about Voinovich's role. The Ohio Republican chairs a Senate subcommittee that deals with nuclear power issues.

The inspector general's office concluded that Voinovich and his staff ``played no role. They were not a factor in this thing at all,'' George Mulley Jr., deputy assistant inspector general, said Wednesday.