Japan’s largest utility will restart its first nuclear power plant since the 2011 Fukushima disaster, a watershed moment in the global return back to atomic energy.

Tokyo Electric Power Co will start the No 6 reactor at its Kashiwazaki Kariwa plant in Niigata prefecture after 7 pm local time on Wednesday, the company said on its website. Tepco, as the utility is known, had previously intended to resume operations on Tuesday, but issues with an alarm system at the facility led to a temporary delay.

Kashiwazaki Kariwa is the world’s biggest nuclear power plant and its restart marks a turning point for Japan, which is still grappling with the fallout from the Fukushima meltdown. Tepco has admitted the facility wasn’t prepared for the massive earthquake and tsunami that overwhelmed the three reactors.

READ MORE: Tepco to restart Japan’s biggest nuclear plant in Jan

The Fukushima disaster upended Japan’s energy policy, forcing the country to depend more on imported fossil fuels. Prior to the accident, atomic power made up a third of electricity generation, and the nation had goals to boost that to 50 percent by 2030. Now, roughly two-thirds of 33 operable reactors are offline.

Japan’s nuclear return is part of a global trend as governments look for ways to decarbonize grids. Companies are also clamoring for clean and stable sources of electricity to meet booming data-center demand to power artificial intelligence. Tech giants such as Microsoft Corp and Amazon.com Inc are securing direct agreements with atomic energy providers in the US.

An independent regulator was created in Japan after Fukushima, and restart reviews dragged on for years as Tepco struggled to secure support from local communities and governments. Unit No 6 at Kashiwazaki Kariwa will be the 15th reactor to come back online under post-Fukushima safety rules.

Tepco announced on Saturday it had suspended a control rod withdrawal test at the reactor after an alarm failed to activate. No issues were found with the rods — a tool that regulates the nuclear chain reaction — after the utility finished checks on Wednesday at Unit No 6, a spokesperson said.

To begin the restart process, control rods will be removed, Tepco’s Risk Communicator Masakatsu Takata said in a briefing earlier in January. The utility will take steps to inspect other critical parts, such as pumps and turbines, and final clearance will be needed from the regulator before commercial operations can be resumed at the end of February, he said.

READ MORE: Revival of Japan’s biggest nuclear plant faces last hurdle

Kashiwazaki Kariwa is Tepco’s only remaining commercial nuclear facility. Unit No 6 is one of seven reactors at the plant, and the first to be restarted, while Unit No 7 also has clearance from the regulator to come back online.