SEOUL, South Korea - The Japanese government declared Friday that the tsunami-stricken Fukushima Dai-ichi nuclear power plant had ceased to leak substantial amounts of radiation, achieving a condition that suggests a critical stable state known as a "cold shutdown."

The announcement came more than nine months after the quake-generated tsunami struck the plant March 11, knocking out its cooling system and eventually causing a series of meltdowns.

Prime Minister Yoshihiko Noda's statement to cabinet members was intended to reassure Japan and the rest of the world that the nation was moving beyond its nuclear nightmare. But critics say the plant, stricken by what many call the worst nuclear disaster since Chernobyl, is continuing to cause harm and that it will take decades to fully decommission it.

Officials say they can now move forward with assessing dangers at evacuation areas. In the days following the disaster, about 80,000 residents were evacuated from communities near the plant after the reactors spewed radioactivity into the air, sea and, soil.

A 12-mile off-limits zone around the plant is expected to remain in effect for years, Japanese authorities acknowledge.

Officials had predicted they would reach the cold shutdown state by early 2012. The government's declaration Friday in support of claims by the plant's operator, Tokyo Electric Power Co., that the reactors have reached that crucial point is one step toward encasing the plant in concrete as a precaution.

Still, Friday's announcement was carefully worded, with officials suggesting that the plant had reached cold shutdown "conditions," since the utility cannot measure temperatures of melted fuel in damaged reactors as precisely as it could in normal facilities.

Facility operators conceded that engineers will not be able to remove spent fuel from the three worst-hit reactors for 10 years, but say they may begin removing fuel from storage pools within the next two years.

Engineers said that establishment of an improvised cooling system to circulate water through the damaged reactors helped create the more stable state. They have also set up a system to decontaminate water that becomes radioactive in the process.