A nuclear power reactor north of New York City will face tighter inspections after an electrical fault and fire in a transformer forced an automatic shutdown.

The fire, which was extinguished in 15 minutes, was outside the nuclear area of the Indian Point 3 reactor, and there was no release of radiation, said Diane Screnci of the Nuclear Regulatory Commission. No injuries were reported.

"The plant is stable and reacted normally," she said. "There's no impact on public health and safety."

Nevertheless, Screnci said, an "unusual event" was declared at the plant, which is on the Hudson River in Buchanan, about 40 miles north of New York City. The declaration, the lowest of several safety alert classifications, required plant owner Entergy Nuclear Northeast to notify the NRC and state and local governments. It was called off after about an hour.

In addition, because it was Indian Point 3's fourth unplanned shutdown since July, the plant's rating in that area went from "green," the best, to "white," Screnci said. The change will mean tighter inspections.

Several officials said Friday's fire, combined with other Indian Point woes, showed the need for a permanent shutdown or at least for an inspection known as an Independent Safety Assessment, which the NRC is resisting.

Rep. John Hall, a Democrat whose district includes the plant, said in a statement that the fire "reinforces the necessity of an objective, truly independent safety study before re-licensing for another 20 years is considered." He listed several recent plant problems, including failed emergency sirens and leaks of radioactive water, and said Entergy's safety assurances lacked credibility.

Sen. Hillary Rodham Clinton said in a release: "This constant stream of problems simply does not square with the insistence of the Nuclear Regulatory Commission and Entergy that an Independent Safety Assessment is not needed at Indian Point."

Entergy spokesman Jim Steets said the cause of the fire was not known. It spread smoke around the area of the transformer yard, which is across a street from the plant, but was confined to the transformer, he said.

The NRC said it was extinguished by the transformer's own "deluge system," as well as the plant's fire brigade. Onsite NRC inspectors made sure proper procedures were followed, the commission said.

Indian Point 2, the other working nuclear reactor on the site, remained up and running, Steets said.

He said the transformer takes electricity produced by the plant and transforms it for use by the metropolitan area's electrical grid.

The shutdown was the second this week at Indian Point 3. A water pump malfunction closed the plant down from 4 a.m. Tuesday to 1 a.m. Wednesday. It had been closed for 24 days until Saturday for scheduled refueling and maintenance.