Nine months after the quake, engineers say reactors at the plant are stable
16 December 2011 Last updated at 04:05
Japan is set to announce that engineers have brought the crippled Fukushima nuclear plant to a “cold shut-down condition”, nine months after the earthquake and tsunami.
PM Yoshihiko Noda is expected to make the announcement later on Friday.
Declaring a cold shut-down condition is seen as a key milestone in efforts to bring the plant under control.
But the government says it will take decades to completely dismantle the plant.
The six-reactor Fukushima Daiichi nuclear plant was badly damaged by the 11 March earthquake and tsunami. Blasts occurred at four of the reactors after waves knocked out vital cooling systems.
Workers at the plant, which is operated by Tokyo Electric Power Company (Tepco), have been using sea water to cool the reactors. Waste water has built up and some contaminated liquid has been released into the sea.
A 20km (12m) exclusion zone remains in place around the plant.
The Japanese government said earlier this year that it was aiming to reach a “cold shut-down condition” at the plant by the end of the year.
This is where water that cools nuclear fuel rods remains below boiling point, meaning that the fuel cannot reheat.
Tepco is still struggling to contain leaks of contaminated water at the plant
Tepco has also defined it as bringing the release of radioactive materials under control and reducing public radiation exposure to a level that does not exceed 1mSv/year at the site boundary.
According to public broadcaster NHK, the nuclear disaster task force will meet on Friday, after which Mr Noda will make the formal announcement.
With the reactors stable, the government will review evacuation zones established in the immediate aftermath of the incident, it reports.
More than 80,000 people had to leave the area, but radiation levels in some places remain too high for them to return home.
Earlier this week, the government said it could take up to 40 years to fully decommission the plant and clean up surrounding areas.
Spent fuel rods and melted fuel inside the reactors must be removed. Waste water must also be safely stored.
Contamination has been found in foodstuffs from the region including rice, beef and fish, while radioactive soil has also been found in some areas.
Some experts have also warned that the plant could be further damaged if a powerful aftershock were to strike.
Engineers are also continuing to encounter new problems – last week Tepco officials confirmed that 45 cubic metres (1,590 cubic feet) of water had leaked into the sea from a crack in the foundation of a water treatment facility.