The Nuclear Regulation Authority (NRA) held a meeting of a panel of outside experts on Oct. 17 to start considering the formulation of standards for ordering a nuclear power plant to shut down in preparation for a giant volcanic eruption.
Arguing that there is a high possibility of smaller volcanic eruptions occurring ahead of a giant eruption, the expert panel showed a proposal to prepare for a giant eruption after a smaller eruption occurs. But the panel did not show specific details of standards.
According to the NRA's proposal, a giant eruption is believed to occur following small-, medium- or large-scale eruptions. With such a possibility in mind, the NRA said that the expert panel would consider how to respond in the event of small- and medium-sized eruptions occurring and extremely abnormal data being observed. The NRA listed crustal movement, seismic activity and temperatures and gasses of a volcano as data to be subject to monitoring.
Meanwhile, there was a spate of suggestions from experts at the meeting that it would be difficult to detect signs of a giant eruption. For example, Tetsuo Kobayashi, professor emeritus at Kagoshima University, said, "Even if there is a significant phenomenon, whether or not it will lead to a giant eruption will not be known until the last minute."
The NRA is to examine data on past volcanic eruptions, but it will likely face difficulties in working out standards as there are very few cases of giant eruptions being observed in the world.
The NRA had given the green light for two reactors at Kyushu Electric Power Co.'s Sendai Nuclear Power Plant in Kagoshima Prefecture to restart, saying, "The possibility of a giant volcanic eruption occurring at the periphery of the nuclear plant is very low." If the NRA deems there is a sign of a giant eruption, it will order a relevant power company to halt the operation of nuclear reactors and take nuclear fuel out from the reactors. But in order to take out nuclear fuel from reactors, several years have to be spent to cool down the atomic fuel first. And yet, nothing has been decided as to where such fuel should be sent.