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Media Advisory: Technical Briefing on the Radiation Accident in Japan

  • the IAEA has offered assistance to the Japanese government, but has not yet been invited to assist in any investigation; an expert team remains on standby
  • under the Convention on Early Notification of a Nuclear Accident, countries are only required to notify the IAEA when there is the risk of transboundary release of radiation, which was not the case in this instance. Hence, the information to the Agency from Japan was voluntarily provided and the IAEA’s activation of its Emergency Response Unit also was done on that basis
  • the Japanese government has provisionally rated this accident as a level 4 on the International Nuclear Event Scale, implying limited risk of radiological contamination off the site
  • high doses of radiation were received by three workers; 2 of whom received doses of at least 8,000 mSievert
  • 36 other workers on-site may have received abnormal doses, as well as 3 firemen and 7 nearby members of the public
  • release of significant radioactive materials into the surrounding environment, other than short-lived gases; was unlikely
  • for reasons unknown as yet, criticality continued on and off over a 17 hour period, until the water jacket surrounding the container in which the criticality occurred was drained
  • the accident was an irradiation accident involving beams of radiation, not widespread contamination or dispersal to the environment
  • the accident cannot be compared to the Chernobyl accident which happened at a specific type of nuclear reactor in limited operation and resulted in wide dispersal of radioactive materials
  • the immediate area within 350 metres of the facility was evacuated and residents were ordered to stay indoors within 10 km of the facility; those measures have now been lifted


Last update: 26 July 2017