Although Tomari Nuclear Power Station was shut down subsequent to the beginning of the – still ongoing – TEPCO-Fukushima nuclear disaster in 2011, electricity is still required to keep the spent nuclear fuel rods cool, so that they don’t melt down. A power outage after the recent 6.6 M earthquake meant that it had to use back-up diesel generators. As can be seen on the map, the nuclear power station isn’t very close to the epicenter. Tomari Nuclear Power Station is the orange skull to the left of the epicenter.
M 6.6 – 27km E of Tomakomai, Japan 2018-09-05 18:07:58 UTC 42.671°N 141.933°E
See: “Japan nuclear plant’s power restored after quake triggers Hokkaido blackout August 6, 2018 (Reuters) – Power was restored to a nuclear energy plant in Hokkaido, northern Japan on Thursday after a strong earthquake left it relying on emergency generators for 10 nervous hours, but it may be a week before lights are back on all over the major island.” Read more here: https://nuclear-news.net/2018/09/06/japan-nuclear-plants-power-restored-after-quake-triggers-hokkaido-blackout
“Nuclear Spent Fuel Damage: Pool Accident, by DAVE LOCHBAUM, DIRECTOR, NUCLEAR SAFETY PROJECT | APRIL 19, 2016, 6:00 AM EDT ” https://allthingsnuclear.org/dlochbaum/nuclear-spent-fuel-damage-pool-accident
“Death toll from Japan quake hits 44, power supply, Toyota output disrupted Posted:Mon, 10 Sep 2018 01:19:28 -0400 The death toll from a powerful earthquake in northern Japan last week rose to 44, with 660 injured, the government said on Monday, as electricity supply remained short and top automaker Toyota suspended work at most of its assembly plants.” http://feeds.reuters.com/~r/reuters/environment/~3/_ZRWCSsIYC8/death-toll-from-japan-quake-hits-44-power-supply-toyota-output-disrupted-idUSKCN1LQ00X
“Toyota to restart all domestic assembly lines by Thursday after quake Posted:Mon, 10 Sep 2018 01:19:28 -0400 Toyota Motor Corp said it would resume operations at all domestic assembly plants by Thursday as a transmission plant in Hokkaido was poised to restart production following last week’s earthquake.” http://feeds.reuters.com/~r/reuters/environment/~3/W-UD__iXDdI/toyota-to-restart-all-domestic-assembly-lines-by-thursday-after-quake-idUSKCN1LQ0C7
Map source and more information: https://earthquake.usgs.gov/earthquakes/eventpage/us2000h8ty#executive