On the heels of the Department of Energy's investigation of uranium enrichment plants in the United States, worker exposure to radiation is in the news again this time in Japan.
On Sept. 30, a major leak at a uranium-processing plant in Tokaimura, Japan, sent radiation levels skyrocketing and injured three workers. More than 310,000 people were ordered not to leave their homes.
By the next day, the Japanese government had lifted the advisory that ordered residents within six miles of the plant to stay indoors. That advisory included closing schools and stopping train service in the region.
The three injured workers remained in a hospital's intensive care Oct. 1. Hisashi Ouchi, 35, and Masato Shinohara, 39, had typical symptoms of radiation sickness shock, diarrhea, a fever, a high white-blood-cell count and reddened skin. The two had improved, but still were in critical condition, doctors said. The third worker Yutaka Yokokawa, 54 was alert and able to walk.
Three firefighters, 36 additional workers and seven residents were exposed to radiation, although none required hospitalization, according to the National News Agency. Exposed workers inside the plant reportedly received radiation of up to 4,000 times the level considered safe.
In what is considered to be the worst nuclear accident in Japan's history, government officials said the accident was contained after workers removed water from cooling equipment from around a tank. The nuclear fission started in the tank when workers mixed uranium with nitric acid to make fuel for a nuclear power plant, said a spokesman for JCO Co., which operates the plant.
In admitting that safety rules were violated, the company spokesman said the workers are believed to have put 35 pounds of uranium into the tank, well over the 4.8-pound limit. Radiation came from neutrons produced in the fission reaction, said an official at Japan's Science and Technology Agency. When the reaction stopped, radiation levels returned to normal after neutrons ceased to be produced.
U.S. Secretary of Energy Bill Richardson, while in Sarov, Russia, said that, while neither the United States nor Russia have been asked to assist, both countries' governments stand ready to help.
"Russian Minister of Atomic Energy Yevgeniy Adamov and I today began assembling a joint team of Russian and American nuclear specialists to be ready to provide assistance to the Japanese people in responding to this incident," Richardson said on the day of the accident. "The Department of Energy (DOE) has experts in several areas who could be helpful, including radiological health, atmospheric monitoring, criticality and robots that could be dispatched to the area."
In the past several weeks, Richardson has been involved in investigating worker contamination of uranium, plutonium and other radioactive materials at DOE gaseous diffusion plants in Kentucky, Ohio and Tennessee. President Clinton has signed into law a bill that funds a portion of the DOE's plan to resolve worker safety and health problems at plants.
Contractor workers, mostly at the Paducah, Ky., uranium enrichment facility, were potentially exposed to plutonium and other radioactive contaminants as a result of the Atomic Energy Commission's reuse of uranium previously used to produce plutonium from the 1950s to the 1970s. Radioactive residues are still present in small quantities at the plant.
See Occupational Hazards' November issue for more information on the DOE investigation. For a complete look at how Paducah workers have been impacted, look for a feature article in OH's December issue. If you're an environmental, health and safety professional who doesn't receive the magazine each month, click on the "Subscriptions" button on the Web site.