18 April, 2016
The 2016 Kumamoto Earthquake Has Not Affected NPPs
Beginning on April 14, a series of intermittent major earthquakes has occurred primarily in Kumamoto Prefecture, the western part of Japan. We mourn the loss of life and express our deepest condolences to the families of the deceased.
Although the scale was great, the intensity of ground motion was substantially below the standard ground motion (Ss) used when designing nuclear facilities, and there have been no abnormalities as a result. In the 2011 Great East Japan Earthquake, similarly, no NPPs, including at the Fukushima Daiichi NPPs, which was severely damaged by tsunami, were affected significantly by the earthquake itself. Thus, again, the strength of designs and measures to protect NPPs against earthquakes has been validated.
In the table below, the status of NPPs that could have been affected by the recent earthquakes is shown. At the Sendai-1 and -2 NPPs, owned and operated by the Kyushu Electric Power Co., the only units in the table in operation at the time, ground acceleration did not reach values that would have triggered automatic shutdown at either unit, and both remain in normal operation.
Figures in parentheses are values set by the Nuclear and Industrial Safety Agency (NISA) when the Regulatory Guide for Aseismic Design of Nuclear Power Reactor Facilities was revised in 2006. They are currently being reevaluated by the NRA.