Experts probing the cause of the plutonium-inhalation accident involving five employees at a fuel research facility in Ibaraki Prefecture are trying to determine whether failures in safety equipment or procedures allowed the deadly powder to escape its container.
The accident might have been caused by the long-term buildup of helium emitted by the plutonium, one expert says.
The accident took place at around 11:15 a.m. Tuesday when five men from the Plutonium Fuel Research Facility at Oarai Research & Development Center were taking stock of a radioactive substance in an old storage container. This process usually involves placing the container into a special machine that adjusts the air pressure to prevent the material inside from being blown into the air.