The Nuclear Regulation Authority said Monday that the Sakurajima volcano in Kagoshima Prefecture doesn’t pose a threat to the Sendai nuclear plant 50 km away.
The Meteorological Agency increased the alert level for the volcano to 4 from 3 on Saturday, advising people within 3 km of the crater to prepare to leave. The highest rating on the scale is 5, when evacuation is ordered because of a high risk of eruption.
Kyushu Electric Power Co., which runs the Sendai nuclear facility, said Monday that operations were normal. A reactor at the facility was restarted last week, the first in Japan to be brought back online under new safety rules set up after the 2011 Fukushima nuclear disaster.
“Regarding the effect from volcanic ash (and other debris), the NRA recognizes that it will not impair safe operations of Sendai facility based on the new regulatory requirements,” the authority said in an email. “It recognizes that Kyushu Electric company appropriately prepares its measure for volcanic activity.”
There are 39 known volcanoes, 14 of which are active, within 160 km of the Sendai plant, according to Kyushu Electric. The company uses seismic sensors and global positioning technology to predict eruptions that may threaten its Sendai reactors.
The company has updated equipment to withstand 15 cm of volcanic ash, and an eruption large enough to have an impact on the facility last happened 30,000 years ago, a spokesman for the utility said.
Sakurajima’s last major eruption was over 10,000 years ago, which wouldn’t have affected the location where the Sendai facility was built, according to simulations, Kyushu Electric said in a March 2014 presentation.
Japan lies in the “Ring of Fire,” an arc of volcanoes and fault lines surrounding the Pacific Basin, and it sits at the three-way meeting point of the North American, Eurasian and Philippine Sea tectonic plates.
Authorities ordered the complete evacuation of Kuchinoerabu Island in Kagoshima Prefecture in May after the Shindake volcano erupted for the second time in 10 months. Last September, more than 50 people, mostly hikers, were killed in an eruption at Mount Ontake between Nagano and Gifu prefectures.