Re-evaluation of INES rating; Effect to the Nuclear Facilities from the earthquake on east area of Japan


Print View Posted on: 12 April 2011

Event Date: 12 April 2011 Event Type: Power Reactor
Event Location: Japan, FUKUSHIMA-DAIICHI INES Rating: 7 (Provisional)

In March 18, rating of the INES on the events in Fukushima Dai-ichi Nuclear Power Station, by the Tohoku Regional Pacific Ocean Offshore Earthquake is temporary estimated Rating 5. However, Nuclear and Industrial Safety Agency (NISA) estimated total amount of discharge from Fukushima Dai-ichi NPS, using the analytical result of the state of nuclear reactor under the cooperation of Japan Nuclear Energy Safety Organization (JNES). As a result of re-evaluation, total amount of discharged I131 is estimated at 1.3E17Bq, and Cs137 is estimated at 6.1E15Bq. Hence NISA concluded that the rating of the accident would be equivalent of Rating 7.
This result is present status of discharge from Fukushima Dai-ichi NPS. Because discharge is on going and the amount of discharge from each reactor is unspecified, NISA will continuously be gathering information and evaluate them.

INES Rating: 7 - Major accident (Provisional) as per 12 April 2011
Release beyond authorized limits? Yes
Overexposure of a member of the public? No
Overexposure of a worker? Yes

Contamination spread within the facility? Yes
Damage to radiological barriers (incl. fuel damage) within the facility? Yes

Degradation of Defence In-Depth Yes

Person injured physically or casualty? Yes
Is there a continuing problem? Yes

Masahiro Yagi
Nuclear and Industrial Safety Agency (NISA/METI)


Site Sponsors
Site Sponsors: IAEA, NEA and WANO
This site is hosted by the International Atomic Energy Agency (IAEA) and co-sponsored by the Nuclear Energy Agency of the Organization of Economic Cooperation Development (OECD/NEA) and World Association of Nuclear Operators (WANO).
Disclaimer
This site is hosted by the IAEA, however, event reports are filed and updated by authorities in participating countries, which remain responsible for all related content. Read more >