Forty nine people were exposed to radiation—two with a potentially lethal dose—after Japan’s worst nuclear accident struck a uranium processing plant on 30 September.
The accident occurred at a facility run by JCO, an affiliate of Sumitomo Metal Mining, in Tokaimura, 70 miles north west of Tokyo, as a result of an attempted short cut.
In the process of purifying reactor fuel, workers were supposed to use an automatic pump to mix up to 2.4 kg of enriched uranium with nitric acid. Instead, they manually used a stainless steel bucket and mixed 16 kg of the fissile material.
The uranium reached a critical mass at 1035 am and set off an uncontrolled chain reaction that emitted radiation for almost 20 hours.
The three workers who carried out the operation reported seeing a blue flash—the Cerenkov radiation that is emitted during a critical reaction—before collapsing with nausea. They were rescued by colleagues and taken to a local hospital by emergency services.
According to doctors, two of the men were exposed to more than the 7 sieverts of radiation that is considered lethal: Hisashi Ouchi, aged 35, and MasatoShinohara, aged 29, received17 sieverts and 10 sieverts respectively. Their supervisor, Yutaka Yokokawa, aged 54, was irradiated by 3 sieverts.
After the men were taken to the National Institute of Radiological Sciences in Chiba, just east of Tokyo, tests on Mr Ouchi and Mr Shinohara showed their lymphatic blood count had plunged to almost zero. Symptoms included nausea, diarrhoea, and dehydration.
Three days after the accident the two men were transferred to the University of Tokyo Hospital for transfusion operations that were seen as the only hope of reactivating their blood producing functions.
At the time the BMJ went to press, Mr Ouchi was due to receive peripheral stem cells from his brother and Mr Shinohara was to have a transfusion from congealed umbilical cord blood. David Kyd, a spokesman for the International Atomic Energy Agency, based in Vienna, said that the chances of the two men surviving were slim.
Full story in News Extra at ww.bmj.com
Figure.
DIT:AP PHOTO/KATSUMI KASAHARA
A man has his radiation level checked in Tokaimura, Japan