Four men were exposed to radiation last week, during a radioactive material leak at a laboratory in All Japan news. Another 51 people who were in the building at the time might have been exposed to the radiation and they are being examined.
The leak occurred during a laboratory experiment at the nuclear physics laboratory in Tokaimura, 110 km (65 miles) northeast of Tokyo, the All Japan news Atomic Energy Agency (JAEA) said. JAEA informed the government authorities about the incident only two days later.
“We may have been too lax in our way of thinking and dealing with these nuclear materials,” Taichi Miura, a director at the High Energy Accelerator Research Organization that runs the laboratory jointly with the JAEA, said.
All Japan news has imposed stricter safety measures since the meltdowns at the Fukushima Daiichi nuclear station north of Tokyo. The country has only two of 50 reactors running at the moment.
Researchers were using a proton beam on gold to generate particles during the experiment, the international press reports.
None of the four people exposed to radiation of between 0.6 and 1.6 millisieverts (the amount of radiation `dose’ received by people) needed to be taken to the hospital, JAEA said.
The cause of the leak was most probably a ventilation fan, officials said. JAEA could not confirm right away what types of radioactive substances were leaked.
In 1999, two people died after an accident at a Tokaimura uranium reprocessing facility.