By Will Davis
Two significant earthquakes have struck Kumamoto Prefecture in Western Japan within a week, and the Japanese nuclear plant owners and their regulator (the Nuclear Regulation Authority, or NRA) have responded to some reignited fears over nuclear plants in this region by beginning to publish reports and data. The data show that at no point was any of the plants in danger.
The Japan Atomic Industrial Forum published a piece on April 18 explaining that the quake accelerations experienced by the various nuclear plants in the region did not approach any of the design limits for these plants—and in fact did not approach at all the seismic shutdown limit for the region’s only operating nuclear plant (two units at Kyushu Electric Power’s Sendai NPP). The JAIF home page is here.
The NRA has released similar information, but in somewhat greater detail. It is also promising to make daily situation updates, although these have not yet begun. How long these will need to be maintained is also unclear. The NRA homepage is here.
Kyushu Electric Power has added a new header to its home page with a link to information specific to its Sendai and Genkai nuclear plants. It has also launched the 24-hour operation of a webcam that looks at the operating Sendai NPP units. The company reported soon after both of the largest recent quakes that the two Sendai units were operating normally and that they would continue to do so, which is important to reconnecting power to the thousands of persons who are without power in the area due to damage to the grid.
The public’s fears are, of course, rooted in the recent memory of the Fukushima Daiichi accident and the after-effects therefrom. What’s being left out of many of the present narratives is the fact that it was the tsunami’s inundation of the nuclear plant site and an extended loss of power and cooling that led to the accident, as the plants operated normally during the 45 minutes between the earthquake (at which they shut down on automatic seismic signal) and the arrival of the tsunami. Japanese nuclear plants have survived many earthquakes over decades, from 7.5 on the Richter scale to even 9.0 (March 2011) without unexpected problems, considering that the automatic seismic shutdown in such a case is expected. None of the nuclear plants in the region has been threatened by any tsunami, even small, during the recent quakes, which have taken place in the land mass and not offshore.
Will Davis is Communications Director and board member for the N/S Savannah Association, Inc. He is a consultant to the Global America Business Institute, a contributing author for Fuel Cycle Week, and he writes his own popular blog Atomic Power Review. Davis is also a consultant and writer for the American Nuclear Society, and serves on the ANS Communications Committee and will serve on the Book Publishing Committee beginning in June. He is a former US Navy reactor operator.