(FORTUNE Magazine) – A cloud of highly toxic and mildly radioactive gas escaped from a Kerr-McGee uranium processing plant in Gore, Oklahoma, killing one worker and hospitalizing 34 people. The poisonous hydrogen fluoride vapor leaked from an overloaded 14-ton shipping cylinder at Kerr-McGee's Sequoyah Fuels subsidiary and spread over a sparsely populated area some 80 miles southeast of Tulsa. The Nuclear Regulatory Commission is investigating. Over the past eight years, the NRC has cited the plant for 15 safety infractions, none serious enough to prevent renewal of its license last September. Based in Oklahoma City, Kerr-McGee is primarily an oil and gas company. The Sequoyah facility converts uranium concentrate into uranium hexafluoride, which is then shipped to government production plants where it is enriched for use in nuclear reactors. Besides Kerr-McGee's plant, only Allied's facility in Metropolis, Illinois, makes uranium hexafluoride in the U.S. Domestic sales have dropped as the U.S. nuclear power industry has slumped, and both companies have tried to tap overseas markets. Kerr-McGee's unit has posted losses for the past two years. Uranium conversion makes up only 2.6% of the company's $3.5 billion in revenues, but it has been a persistent thorn in the company's side. In 1974 Karen Silkwood, a Kerr-McGee lab analyst, became contaminated with plutonium and accused her employers of safety violations. She died in a mysterious car crash and later was the subject of a popular motion picture starring Meryl Streep.