The company was trying to send power to the grid from the reactor when the turbine shut down, which led to the automatic shutdown of the reactor, a company spokesman said, according to Reuters.
Reactors in Japan are required to be shut after 13 months of commercial operations for planned maintenance. All of the country's units were eventually idled in the wake of the meltdown at Tokyo Electric Power in March 2011.
That led to a period of nearly two years between September 2013 and August 2015 when Japan had no nuclear power generation, the longest since it started using atomic energy in the early 1970s.
The three reactors that are in operation have a combined capacity of 2.65 gigawatts, or 6.3% of Japan's total nuclear capacity, Reuters calculations show.
Japan's nine major power monopolies and a wholesaler, Japan Atomic Power Co, have 43 nuclear reactors for commercial use, with a total generating capacity of 42,048 megawatts, according to the report.
