The Real Cause of Nuclear Accident

On September 30, 1999, a nuclear chain reaction was set off at the uranium processing plant of JCO Co. in Tokaimura, and lasted for almost a day, contaminating dozens of workers and spewing radiation into the atmosphere. About 310,000 people living within 10 kilometers of the plant were warned to remain in their homes with windows and vents shut for more than a day. Some 80 people living within 350 meters of the plant, evacuated soon after the accident, were still barred from returning to their homes on 2 October. This was Japan's worst-ever nuclear accident.

Japanese newspapers quoted officials from the JCO Co. as saying at a news conference, "The nuclear chain reaction began around 10:35 a.m. 30 September when workers skipped a key step that would have prevented the start of the reaction. They apparently used buckets to transfer a uranium solution into a mixing tank. Because the employees were doing the job by hand, instead of using a required apparatus, they mistakenly loaded 16 kilograms of uranium into a container, nearly eight times the normal amount. They also appear to have transferred the uranium solution to the wrong tank." (Adapted from the website news of CNN.)

The above report gives us an impression that the accident was entirely caused by the workers' error, but fullest consideration should be given to the more basic reason that lead the human error to the disaster. Is it not a gross administrative failure to permit the establishment of a nuclear fuel plant without any fail-safe system against the fission chain reaction?

Related References

• IAEA-WHO, Diagnosis and Treatment of Radiation Injuries, Safety Report Series, No. 2, IAEA, Vienna (1998).
• IAEA-WHO, Planning the Medical Responses to Radiological Accidents, Safety Report Series, No. 4, IAEA, Vienna (1998).
• IAEA-ILO-WHO, Health Surveillance of Persons Occupationally Exposed to Ionizing Radiation, Safety Report Series, No. 5, IAEA, Vienna (1998).