Japan has shut down a reactor at the world’s largest nuclear power plant just one day after beginning its long-awaited restart, following a technical malfunction involving critical safety equipment, according to the BBC. The issue occurred at the No. 6 reactor of the Kashiwazaki-Kariwa nuclear power plant, a vast facility that has been largely idle since the Fukushima disaster in 2011.
4he restart process began when workers started withdrawing neutron-absorbing control rods from the reactor core to initiate stable nuclear fission. Hours later, however, a malfunction in electrical equipment linked to the control rods forced operator Tokyo Electric Power Company Holdings to suspend the operation and return the reactor to a shutdown state for further inspection.
TEPCO said the reactor remains stable and that there has been no radioactive release or environmental impact. A company spokesperson confirmed the issue was detected early and emphasized that safety systems functioned as designed. Control rods are among the most critical components in a nuclear reactor, used to regulate or halt the chain reaction by absorbing neutrons, which makes any fault involving them particularly sensitive.
The restart had already faced delays. It was originally scheduled earlier in the week but was postponed after another control-rod-related issue was detected during pre-start checks. Although that earlier problem was resolved, the latest malfunction has once again cast uncertainty over when the reactor will actually begin supplying power.
Kashiwazaki-Kariwa is the largest nuclear plant in the world by installed capacity, with seven reactors capable of generating enormous amounts of electricity, though only one unit was slated for restart. The entire facility was taken offline after the 2011 earthquake and tsunami that triggered meltdowns at the Fukushima Daiichi nuclear power plant, also operated by TEPCO.
Japan’s government has been pushing to bring reactors back online as the country grapples with high energy costs, heavy reliance on fossil fuel imports, and rising electricity demand driven by data centers and artificial intelligence. Officials also see nuclear power as essential to meeting Japan’s goal of carbon neutrality by 2050.
If fully operational, the No. 6 reactor alone could produce around 1.35 million kilowatts of electricity, enough to power more than one million households in the greater Tokyo area. Despite this, public opinion in Niigata Prefecture remains sharply divided. Surveys show a majority of residents oppose the restart, citing seismic risks and lingering distrust of TEPCO, while a sizable minority supports it for economic and energy-security reasons.
Opposition groups argue the plant sits near active fault lines and point to damage caused by a strong earthquake in 2007. Earlier this month, nearly 40,000 signatures were submitted to regulators and TEPCO demanding the restart be halted permanently.
The abrupt shutdown, coming just a day after restart procedures began, underscores how politically and technically fragile Japan’s nuclear revival remains, more than a decade after Fukushima reshaped the country’s energy debate.