Radiation leak at Japan lab; small impact expected

Radiation leak at Japan lab; small impact expected
Local government officials investigate the inside of nuclear research lab J-PARC in Tokaimura, Ibaraki prefecture, Saturday, May 25, 2013. The nuclear research lab in northern Japan has reported a radiation leak that may have affected 55 people, though none were hospitalized and no impact was expected outside the facility. (AP Photo/Kyodo News)

An atomic research lab in northern Japan has reported a radiation leak that may have affected about 50 people, though none were hospitalized and no impact was expected outside the facility, the lab's operator said Saturday.

The Atomic Energy Agency said the accident occurred Thursday in its Hadron Experimental Facility at the Japan Research Complex in the town of Tokaimura, where at least two previous radiation accidents have occurred.

Researchers were trying to generate particles by directing a at some gold when their equipment overheated, causing the evaporation and release of some radioactive gold, the government-run JAEA said in a statement. The leak originally was thought to have been contained inside the lab, and when a ventilation fan was switched on the radiation spread, it said.

The JAEA said it was studying the potential environmental impact from the radiation leak, but did not expect any effect on surrounding areas.

On Saturday, officials from the JAEA and the research complex apologized for the accident. The minister of Education, Science and Technology, Hakubun Shimomura, described it as "regrettable."

Four researchers were tested after the incident, with the highest found to be 2 millisieverts, the JAEA statement said. That's near the average annual background dose for someone living in Japan. Nuclear workers generally are limited to 100 millisieverts of exposure over five years.

Radiation leak at Japan lab; small impact expected
The inside of nuclear research lab J-PARC is seen in Tokaimura, Ibaraki prefecture, Saturday, May 25, 2013. The nuclear research lab in northern Japan has reported a radiation leak that may have affected 55 people, though none were hospitalized and no impact was expected outside the facility. The Japan Atomic Energy Agency said Saturday that the accident occurred Thursday at a nuclear physics lab in Tokaimura, the site of at least two previous radiation accidents.(AP Photo/Kyodo News)

The belief that the leak had been contained led the research institute to delay reporting the incident until Friday, when it notified both the Nuclear Regulation Authority and the local government, the JAEA said. Work was suspended at the research facility.

Japan's has been in crisis since the March 2011 accident at the tsunami-hit Dai-ichi nuclear plant, the country's worst-ever atomic energy disaster. Most of Japan's remain closed after they were shut down for safety checks.

On May 17, the president of the JAEA, Atsuyuki Suzuki, resigned after the country's nuclear watchdog announced that the trouble-plagued Monju next-generation test reactor would not be allowed to restart due to safety violations. Monju was meant to enable Japan to dispose of atomic waste and reduce the country's plutonium stockpile.

Tokaimura was the site of Japan's second-worst nuclear accident, in September 1999, when two workers were killed by a radiation leak at a fuel-reprocessing plant when they tried to save time by mixing excessive amounts of uranium in buckets instead of using special mechanized tanks.

Hundreds of people were exposed to radiation, and thousands of residents were evacuated as a precaution. The government assigned the accident a level-4 rating on the International Nuclear Event Scale, which ranges from 1 to 7.

In March 1997, at least 37 workers were exposed to low doses of radiation in a fire and explosion at a different nuclear reprocessing plant in Tokaimura.


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