Kyushu Electric called it a small error and said that the automatic shutdown it triggered had gone smoothly. But some critics warned that the episode constituted a serious safety lapse and pointed to a more widespread problem at other plants.
Since then, however, the utility has submitted — and Japan’s nuclear regulators have checked and approved — operation manuals for that reactor, paving the way for a restart.
“If this is a decision reached by the central government after ample checks, we accept,” Mr. Furukawa told reporters Tuesday before the restart.
The reactor at the Genkai plant was started up around 11 p.m. local time and was set to reach 100 percent generating capacity on Wednesday, Kyushu Electric said. But the reactor’s run will be brief: the same reactor must be stopped in mid-December for routine maintenance.