The nearest houses were a half-mile south-southeast of the plant near Gore, which has a population of about 500. Kerr-McGee officials said people living in the path of the leak would be given medical examinations as a precaution.
Brisk winds of nearly 30 m.p.h. "dissipated" the gas rapidly, said Clyde Wisner, regional director of the Nuclear Regulatory Commission's office in Bedford, Texas.
By late last night, however, 73 plant workers and area residents turned up at Sequoyah Memorial Hospital, complaining of skin and eye irritation from the toxic gas.
Charles Wade, a hospital administrator, said 29 people were admitted for observation and were in good condition. He said many of those seeking treatment had driven through the area at the time of the accident.
Eight other workers had been taken to the hospital immediately after the accident for treatment of exposure to hydrofluoric acid, which is formed when uranium hexafluoride mixes with air. Seven workers were in stable condition, and one was treated and released.
Another employee, James Harrison, 25, of Vian, Okla., died at Sparks Regional Medical Center in Fort Smith, Ark., about four hours after the accident at 11:30 a.m.
Harrison suffered "toxic chemical exposure, with hydrofluoric acid burns to the face and lungs," said Carol Martin, a spokeswoman at the hospital.
Stauter did not say what caused the leak at the 32-employee plant, which purifies uranium for production of nuclear fuel rods. Rick Pereles, another Kerr-McGee spokesman, said the container was being heated at the time.
Kerr-McGee officials said the leak occurred in a pressurized 14-ton cylinder containing uranium hexafluoride that "ruptured" but did not explode.
A company spokeswoman, Donna McFarland, said the mist that escaped appeared to have settled within the immediate confines of the plant, which is situated on a 1,200-acre site in eastern Oklahoma, near the Arkansas border.
The plant was evacuated and shut down, and a team from the NRC was sent to investigate.
Michael Herndon, an emergency room physician at Sequoyah Memorial Hospital, said the people admitted there were treated for exposure to hydrofluoric acid, which "may cause irritation to skin, eyes and the respiratory tract."
"We have absolutely no evidence of radioactive exposure," he said.
NRC spokesman Joe Fouchard in Washington said the uranium hexafluoride is used to convert uranium ore into fuel for nuclear power plants.
"It's more of a chemical problem than a radiation problem," Fouchard said of the leak. "But you still don't want to get it in the body."
Stauter said the leak sent radioactive gases into the air, but he indicated there was no danger from the radioactivity to the area.
"The heavier uranyl fluoride particles settled out in the immediate area of the plant," Stauter said. "A thorough radiation survey will be conducted; however, a preliminary survey indicated that radioactivity on the public highways in the area is at normal background levels."
The Oklahoma Highway Patrol reopened Interstate 40 after the Sequoyah County Civil Defense said the air was clear of unusually high radiation.
Kerr-McGee is the same company that employed Karen Silkwood, a union activist who worked at the company's nuclear facility in Crescent, Okla., before she died in a car accident in November 1974.
Silkwood, who had been exposed to a large amount of radiation a week before her death, was on the way to meet with a New York Times reporter when she died. She had promised to deliver evidence of safety problems at the plant.