The company said smoke was detected in the turbine building of reactor No. 1 at the Fukushima Daini nuclear power plant around 6 p.m. (5 a.m. ET).
Smoke could no longer be seen by around 7 p.m. (6 a.m. ET), a company spokesman told reporters.
The Fukushima Daini nuclear power plant is about 10 kilometers (6 miles) from the Fukushima Daiichi nuclear power plant, where workers have been scrambling to stave off a meltdown since the March 11 earthquake and tsunami knocked out cooling systems there. (read more)