The Japan Times reported that at Tokyo Electric Power Company Holdings' (Tepco) Kashiwazaki Kariwa nuclear power plant officials "confirmed Monday that water from a spent fuel pool spilled over due to the earthquake, but that no abnormalities in operation had been detected". In an update issued on Tuesday, Tepco said: "At the Kashiwazaki-Kariwa nuclear power plant, the readings on the stack monitors and monitoring posts installed at the power plant site boundaries are within normal fluctuation ranges, and there is no radioactivity impact on the outside world. The spent fuel pool cooling system is in operation at all units, and there are no abnormalities in fuel cooling. As of 12:25 pm on 2 January, all patrols had been completed and no abnormalities caused by this earthquake were confirmed."

https://www.world-nuclear-news.org/Articles/No-abnormalities-reported-at-Japanese-nuclear-plan