TOKYO — For more than four years since the nuclear meltdowns in Fukushima in 2011, Japan has been debating whether it should permanently abandon a technology that went so disastrously wrong but that for years was seen as essential to its economy.

Governments have offered differing answers. The public has sent confusing signals.

But on Tuesday, the country took what appeared to be a decisive step toward resurrecting the nuclear industry and ending a de facto freeze on the use of atomic power, as an electric utility restarted one of dozens of reactors that were taken offline after the Fukushima disaster.

The reactor at the Sendai Nuclear Power Plant, in Kagoshima Prefecture, was the first to return to service since government regulators introduced upgraded safety standards two years ago. Most of Japan’s 48 operable commercial nuclear reactors were shut down soon after the meltdowns at Fukushima, and none have operated since 2013.

The government of Prime Minister Shinzo Abe supports restarting idled reactors that meet the enhanced safety standards, arguing that Japan’s economy depends on the low-cost power they provide.