Tokyo, April 6 : The operator of Japan's Fukushima Daini Nuclear Power Plant, a facility currently being decommissioned, has said it suspended cooling of a spent fuel pool after a pump malfunction triggered an alert.

Tokyo Electric Power Company Holdings (TEPCO) said an alarm for the spent fuel pool of the plant's No. 1 reactor went off at around 2:45 p.m. local time on Sunday. Workers shut down the pump after smoke was detected at the site, halting the pool's cooling system, reports Xinhua news agency.

Radiation levels around the nuclear plant have shown no change, and no injuries have been reported so far, TEPCO said, adding that it was investigating the cause of the malfunction and working to repair the pump as quickly as possible to restore cooling.

According to public broadcaster NHK, the pool water temperature stood at 26.5 degrees Celsius when the cooling system was halted, leaving about 8 days before it would exceed the 65-degree Celsius threshold set for safe operation.

The four-reactor Fukushima Daini plant sits about 12 km south of the Fukushima Daiichi plant, both of which were crippled by a massive earthquake and an ensuing tsunami in March 2011, prompting TEPCO to decommission both facilities.

Earlier on April 2, Japan began the first round of discharge of nuclear-contaminated wastewater from the crippled Fukushima Daiichi Nuclear Power Plant into the ocean in fiscal 2026.

The latest discharge is the 19th round of the ocean release since the operation began in August 2023, according to the plant's operator TEPCO.

In this round, set to run through April 20, about 7,800 tonnes of wastewater will be discharged, TEPCO said.

The utility plans to discharge a total of 62,400 tonnes of contaminated water in eight rounds in fiscal 2026, which began on Wednesday.

Hit by a 9-magnitude earthquake and an ensuing tsunami on March 11, 2011, the Fukushima nuclear plant suffered core meltdowns that released radiation, resulting in a level-7 nuclear accident, the highest on the International Nuclear and Radiological Event Scale.

Despite opposition from local fishermen, residents and the international community, ocean discharge of the Fukushima nuclear-contaminated water began in August 2023. So far, approximately 141,000 tonnes of wastewater have been released into the sea.

/IANS