Japan set to declare Fukushima plant shutdown

Prime Minister Yoshihiko Noda was expected to tell a disaster-weary public that all reactors at the plant, struck by a titanic tsunami in March, were in a state of cold shutdown and were no longer at any risk of spontaneous fission.

Stabilisation of the reactors, whose molten cores spewed radioactive particles into the air and sea, will mark the end of what the government has dubbed "Step Two" of the clean-up.

The initial success of Step One - the stable cooling of reactors and used fuel pools - was announced in July, after the quake-triggered tsunami pummelled the plant on March 11 and laid waste to much of the northeast coast.

Sawada stressed that the use of the term "cold shutdown" by the government and plant operator Tokyo Electric Power (TEPCO) did not indicate that all four disaster-hit reactors were now safe.

After the March disaster, an exclusion zone around the plant was established with tens of thousands of people evacuated to avoid their being exposed to dangerously high levels of radiation.

Swathes of this zone remain polluted, with the clean-up plodding along amid warnings that some towns could be uninhabitable for three decades.

While the natural disaster claimed 20,000 lives, the nuclear emergency has recorded no direct casualties, but it has badly dented the reputation of a technology on which Japan previously depended for a third of its electricity.

Chief Cabinet Secretary Osamu Fujimura said the government's nuclear task force would meet Friday afternoon to make the decision on declaring cold shutdown.

On March 11, waves up to 14 metres high swamped the reactors' cooling systems, sparking meltdowns, explosions and the release of radioactive material in the world's worst nuclear accident since Chernobyl in 1986.