Nuclear reactor owned by Fukushima plant operator TEPCO to shut down again hours after restart

Japan’s Largest Nuclear Reactor Forced to Shut Down Hours After Historic Restart

A reactor at the world’s largest nuclear power plant was shut down Thursday due to a technical malfunction, just hours after restarting for the first time since the 2011 Fukushima disaster, according to Tokyo Electric Power Company Holdings (TEPCO).

The No. 6 reactor at the Kashiwazaki-Kariwa plant in north-central Japan had begun operations Wednesday night after a 14-year hiatus. Plant workers had initiated the process by removing neutron-absorbing control rods from the reactor core to start stable nuclear fission.

However, the restart was short-lived. Operations were suspended when an alarm was triggered after only 52 of the 205 control rods had been removed, prompting plant officials to initiate a complete shutdown.

“The equipment is essential to safe operation, and we will examine it inside out,” said Kashiwazaki-Kariwa plant chief Takeyuki Inagaki during a news conference. “The reactor will not be restarted until the cause is found and appropriate measures are taken.”

While TEPCO maintains there were no safety issues resulting from the malfunction, Inagaki acknowledged the investigation and resolution would not be quick. “I don’t think this is going to be resolved in a couple of days,” he said.

The setback represents a significant blow to Japan’s nuclear energy revival efforts. The resource-poor nation has been accelerating its nuclear power program to address growing electricity demands and reduce dependence on imported fossil fuels. Since the 2011 Fukushima disaster, 14 nuclear reactors have resumed operations across Japan, but the Kashiwazaki-Kariwa restart marked the first for a TEPCO-managed facility.

TEPCO’s nuclear operations have been under intense scrutiny since the company also manages the Fukushima Daiichi plant, where multiple reactors experienced meltdowns following the devastating 2011 earthquake and tsunami. The disaster released substantial radioactive contamination, rendering some surrounding areas uninhabitable even today. Government and independent investigations attributed the Fukushima catastrophe to TEPCO’s poor safety culture and inappropriate relationships with regulatory authorities.

The cleanup at Fukushima continues, with costs estimated at 22 trillion yen (approximately $139 billion), while TEPCO works to rebuild public trust and its operational reputation.

The Kashiwazaki-Kariwa plant, located about 220 kilometers (135 miles) northwest of Tokyo, houses seven reactors with a combined capacity of 8 million kilowatts, making it the world’s largest nuclear power facility. However, all units have remained dormant since the year following the Fukushima disaster.

Had the restart been successful, the No. 6 reactor would have generated an additional 1.35 million kilowatts of electricity—enough to power more than one million households in the Tokyo metropolitan region. This capacity represents a crucial component of Japan’s energy strategy as the country faces increasing electricity demands.

TEPCO currently plans to restart only two of the plant’s seven reactors in the coming years, reflecting the cautious approach to nuclear power that has characterized Japan’s energy policy since 2011.

The malfunction and subsequent shutdown highlight the ongoing challenges facing Japan’s nuclear industry as it attempts to regain operational momentum while addressing safety concerns and rebuilding public confidence. Despite rigorous new safety standards implemented after Fukushima, technical issues continue to complicate the nation’s nuclear revival efforts.