TOKYO — A two-month shutdown of Japan’s nuclear power plants ended Sunday when officials at a western plant reactivated a reactor for the first time since last year’s disaster in Fukushima.
The restarting of reactor No. 3 at the Ohi nuclear plant was ordered two weeks ago by Prime Minister Yoshihiko Noda, in a decision that has spurred growing public protests. The plant’s operator, Kansai Electric Power, had been working since then to prepare the reactor to resume operations Sunday.
All of Japan’s 50 functional reactors were taken offline one by one for safety checks after the disaster at the Fukushima Daiichi plant, which contaminated a large part of northern Japan with radiation.
The last reactor was shutdown in early May amid widespread public concern over the safety of nuclear plants in the event of another large earthquake and tsunami of the sort that struck Fukushima in March 2011.
Noda said the restarting of the reactor was necessary to avoid crippling power shortages in the heavily urbanized Kansai region, which the plant serves. However, his decision has drawn unusually vocal public opposition in normally compliant Japan, with many Japanese saying that he ignored safety concerns to protect the powerful nuclear industry.
Over the weekend, about 200 protesters blocked the road to the Ohi plant. Kansai Electric said it had enough staff members in the plant to restart the reactor, but a senior vice minister from the ministry in charge of nuclear power had to be ferried to the plant by boat.
‘‘I’m watching this with a tense feeling,’’ the official, Seishu Makino of the Trade Ministry, said of the restart, according to Japanese news reports. ‘‘The government has taken a necessary step forward despite controversy that has divided the nation.’’
About 1,000 protesters marched Sunday in central Tokyo, just two days after tens of thousands of chanting antinuclear demonstrators filled streets in front of the prime minister’s residence.
Despite the protests, Kansai Electric said it had pulled out the control rods in the reactor core on Sunday evening local time, allowing nuclear fission to resume. The operator said it hoped to have a sustained nuclear reaction by Monday morning, and the first transmission of electricity Wednesday.