Here are key developments in Japan as the country prepares to announce the cold shutdown of stricken reactors at its Fukushima nuclear plant, nine months after a massive quake and tsunami triggered the worst atomic accident since Chernobyl in Ukraine in 1986.

- March 11, 2011: A 9.0-magnitude earthquake, the world's fourth largest since 1900, strikes off Japan's northeast coast, triggering a massive tsunami that destroys entire towns and villages along the Pacific coast and kills about 20,000 people.

The power supply and reactor cooling systems at the coastal Fukushima Daiichi nuclear power plant about 220 kilometres (135 miles) northeast of Tokyo are damaged, causing fuel inside to overheat.

- March 12: The government orders the evacuation of residents living near the plant, where an explosion rips through a reactor building.

- March 14: A second explosion hits the plant.

- March 15: Two more blasts and a fire rock the plant, and radiation levels reach dangerous levels.

- April 1: Japan announces start of the "rehabilitation and reconstruction phase".

- April 4: Operations start to dump 11,500 tonnes of radioactive water into the Pacific amid continued emergency cooling operations.

- April 7: Four people are killed and 140 injured in a new 7.1 magnitude quake in the northeast, one of more than 500 strong aftershocks so far.

- April 12: Japan upgrades its assessment of the severity of the nuclear emergency to a maximum seven on an international scale -- equal with Chernobyl, although less radiation was released.

- April 22: Japan approves an initial disaster recovery budget of four trillion yen ($49 billion).

- May 5: Nuclear plant workers enter a Fukushima reactor building for the first time since the explosion.

- May 6: Japan's government decides to ask another nuclear plant operator to shut two reactors at the quake-prone Hamaoka plant southwest of Tokyo.

- May 11: Emperor Akihito visits evacuees from the radiation zone.

- May 19: Data shows Japan's economy plunged back into recession in the first quarter because of the impact of the disaster.

- May 26: Prime Minister Naoto Kan says Japan will boost its share of green energy to 20 percent of total power supply by 2020 and review from scratch plans for any new reactors.

- May 27: Fitch Ratings agency revises its debt outlook for Japan to negative from stable.

- June 7: Japan more than doubles its initial estimate of radiation released from the Fukushima nuclear plant in the week after the tsunami.

- July 5: Japan's cabinet approves a second special disaster recovery budget of two trillion yen ($24 billion).

- Disaster reconstruction minister Ryu Matsumoto quits after causing a furore with scathing remarks to leaders of tsunami-hit regions.

- July 19: Japan bans all cattle shipments from Fukushima prefecture over radiation fears.

- July 28: Japan widens its ban on beef from the disaster zone.

- August 4: The government says it will fire three top energy officials over their handling of the disaster.

- August 8: UN chief Ban Ki-moon visits the area close to the plant.

- August 18: Tests find traces of radioactive elements in the thyroid glands of 45 percent of children from the region around the stricken plant, but they are not present at dangerous levels.

- August 25: Japan lifts a ban on beef from disaster-hit regions.

- August 26: Kan resigns after just 15 months in office following criticism of his leadership in the aftermath of the twin disasters.

- August 30: Kan's finance minister Yoshihiko Noda becomes Japan's sixth new prime minister in five years.

- September 10: The minister for economy, industry and trade is forced to quit after describing the Fukushima evacuation zone as a "town of death".

- September 13: Noda vows to reduce atomic power use.

- September 19: Tens of thousands of people rally in Tokyo calling for an end to nuclear energy in Japan.

- September 30: Japan lifts evacuation advisories for five areas near the crippled plant.

- October 6: A worker at the stricken Fukushima nuclear power plant dies. It is unclear whether his illness was related to radioactive leaks.

- November 2: Plant operator Tokyo Electric Power (TEPCO) says it fears that nuclear fission has resumed inside one of the Fukushima reactors.

- November 4: TEPCO says it expects a net loss of 576.3 billion yen ($7.4 billion) for the fiscal year to March 2012.

- Japan agrees to give TEPCO $11.5 billion to help it pay compensation to those affected by the disaster.

- November 15: The UN atomic agency praises Japan's clean-up efforts but says there is still room for improvement.

-- Scientists warn that land in parts of Japan is no longer safe to farm because of high levels of radiation in the soil.

- November 16: Japan announces its first ban on rice produced near the crippled plant after samples showed radioactive contamination well above legal limits.

- November 21: Parliament passes a third extra recovery budget of 12.1 trillion yen ($157 billion).

- December 6: TEPCO says that highly radioactive water has leaked into the Pacific, and promises to prevent similar incidents.

- Radiation contamination has been found in a leading brand of Japanese baby formula, its manufacturer says.

- December 9: The former chief of the crippled plant has cancer of the esophagus, the operator says, but adds it is unlikely to be linked to radiation.

- December 16: Japan looks set to announce it has finally tamed the leaking reactors with the declaration they are in a state of cold shutdown after nine months.