TOKYO (Reuters) - The operator of Japan's tsunami-hit Fukushima nuclear power plant said Wednesday that it would stick to its timetable of trying to achieve "cold shutdown" of damaged reactors by January, though technical problems could delay the plan.
The Fukushima Daiichi plant was damaged in March by a earthquake and tsunami that left more than 20,000 people dead or missing. The nuclear accident was the worst of its kind since the explosion and fire at Chernobyl in Ukraine in 1986.
"There is no change to the basis of our timeframe. But regarding our aim to bring rectors and fuel pools to cold shutdowns, we have succeeded in further stabilizing the situation, Zengo Aizawa, Tepco's vice president, told reporters.
Tokyo Electric Power Co (Tepco) first announced the cleanup plan in April, proposing to bring under control three nuclear reactors and four pools containing spent nuclear fuel at the Daiichi plant.
Cold shutdown is a state where water used to cool nuclear fuel rods remains below 100 degrees Celsius, making the fuel safe from heating up again.
Cooling systems were knocked out in March, causing meltdowns of nuclear fuel rods at three of the six reactors at the plant, 240 km (150 miles) north of Tokyo. Hydrogen explosions damaged buildings housing the reactors days after the disaster.
Tepco Wednesday said it had achieved ahead of schedule its aim of bringing the spent fuel pools to stable temperatures and that it would try to further cool the reactors by adjusting the amount of water being pumped into them.
"The cooling at the plant made progess with the extreme effort of workers under very tough conditions," Nuclear Crisis Minister Goshi Hosono told reporters alongside Tepco officials.
But Tepco said it still had to decontaminate large amounts of water tainted by radiation, another key step in the cleanup.
Decontaminating tainted water is critical as the treated water is reused as coolant through a circulatory system built after the March disasters.
The newly built circulatory system has freed Tepco from the need to pump in tens of thousands of litres of water to cool the reactors and spent fuel pools. Much of the water had ended as contaminated runoff at the plant needing treatment or removal.
Decontamination has been delayed by repeated breakdowns of instruments designed to remove harmful substances. About 42,000 tonnes of contaminated water had been processed by August 9, with roughly 120,000 tonnes still left.
Experts say Tepco could face further delays if damage to the plant turns out to be worse than expected.
Fumiya Tanabe, director at the Sociotechnical Systems Safety Research Institute, suggested that the large amounts of water poured in during the early days of the disaster could mean that fuel in one reactor may have melted twice -- and not just once.
"The damage to the reactors could be worse than anticipated and if this is the case it may delay Tepco's clean up timetable," he said.
The utility said it was investigating the suggestion, though a spokesperson said it was uncertain when results would be released.
The disaster has caused Japan to rethink energy policy. Only 15 of 54 reactors remain on stream after safety checks were conducted, as local governments have opposed their restart. Parliament is set to pass a bill to promote the use of renewable energy as part of efforts reduce reliance on nuclear power.
Living in fear of radiation has become a part of daily life. Consumers have become increasingly worried about food safety following cases of contaminated vegetables, tea, milk, seafood and water due to radiation leaks from the Daiichi plant.
Editing by Ron Popeski