IAEA mission to visit Onagawa

27 July 2012

The International Atomic Energy Agency (IAEA) is sending a team of experts to the Onagawa nuclear power plant in northeastern Japan to study the impact of the massive earthquake and tsunami of 11 March 2011 on the plant's structures and systems.

Onagawa (Tohoku)
Onagawa's elevated position helped protect it from the tsunami (Image: Tohoku)

The 20-strong mission - comprising IAEA staff, members of national regulators and external experts - will visit Japan between 29 July and 11 August. The team will be led by Sujit Samaddar, the head of IAEA's International Seismic Safety Centre (ISSC). It will visit the three-unit plant in Miyagi Prefecture, which is operated by Tohoku Electric Power Company.

All three units at Onagawa automatically shut down, as designed, when the earthquake occurred. Onagawa 1 briefly suffered a fire in the non-nuclear turbine building. All three units have since remained offline. The plant sustained far less damage than expected, considering the magnitude of the earthquake and the height of the subsequent tsunami. A major contributing factor to this is that the plant sits on an elevated embankment almost 14 metres above sea level. Although the earthquake knocked out four of the five external power lines, the remaining line provided sufficient power for the plant's three reactors to be brought to cold shutdown.

The mission will "look at how parts of the plant's structure, systems, and other safety-related components performed during the earthquake and tsunami," the IAEA said. The findings "will be provided to the IAEA seismic experience database to be made available to IAEA member states in developing earthquake preparedness and response plans."

The IAEA launched the ISSC in 2008 to address in an integrated manner the safety of nuclear installations. The role of the centre is to assist IAEA member states in external hazard assessment, and in aspects of site selection and site evaluation. The ISSC develops IAEA Safety Standards related to site selection and evaluation, as well as seismic design.

Researched and written
by World Nuclear News