A Japanese power company reactivated a nuclear reactor on the south-western island of Shikoku on Friday for the first time in more than five years, it said.
Reactor 3 at the Ikata Nuclear Power Station in Ehime prefecture was brought back online after the utility lifted control rods that are used to contain nuclear fission, said president Hayato Saeki in a statement.
The reactor is expected to start generating and transmitting electricity on Monday and resume commercial operation in September in its first operation since it was suspended in April 2011 for regular maintenance.
“We lodge a strong protest” to the operator as it has gone ahead with the restart despite strong local opposition, said environmental group Friends of the Earth Japan.
The group said there is no feasible evacuation plan for about 5,000 residents on a narrow peninsula called Sadamisaki, where the plant is located.
They are likely left without an overland escape route in the event of a severe accident, it added.
Kunihiko Shimazaki, a former member of the Nuclear Regulation Authority, warned earthquake hazards may have been underestimated in the screening process of Japan’s reactors, especially those in the western part of the country, including the ones at Ikata.
Critics urged the operator to postpone restarting the reactor after two powerful earthquakes rocked Kumamoto in April, 170 kilometres south-west of the Ikata plant.
The Ikata reactor is the fifth to be reactivated in Japan since tighter safety regulations which were put in place after the country's worst nuclear accident at Fukushima in 2011 forced many to shut down.
The Fukushima Daiichi Nuclear Power Station suffered a triple meltdown after it was hit by an earthquake and resulting tsunami.
But two reactors were halted in March after a court issued an injunction order prohibiting operator Kansai Electric Power from running the units at Takahama Nuclear Power Station on the Sea of Japan coast due to safety issues.
Japan ended nearly two years without nuclear power in August 2015 when Kyushu Electric Power restarted a reactor on the southern island of Kyushu, and a second two months later.