TOKYO (Reuters) - Following are main developments after a massive earthquake and tsunami devastated northeast Japan and crippled a nuclear power station, raising the risk of uncontrolled radiation.
- Japan's nuclear safety agency says cannot say if the quake-damaged nuclear reactors are under control.
- Japanese engineers say entombing the Fukushima Daiichi plant with concrete and sand may be a last resort to prevent a catastrophic radiation leak, the method used at Chernobyl in Ukraine in 1986.
- Workers were dumping water to cool the most critical No.3 reactor and planned to run a power cable to reactors No.1 and 2 by Saturday to restart the water pumps needed to cool overheating fuel rods.
- Japan's nuclear agency says priority is to get water into spent fuel pools, particularly in reactor No. 3, which contains plutonium.
- The agency also raised the incident level at the stricken power plant to a 5 on a 1-7 scale. That would suggest a level of seriousness on par with the Three Mile Island nuclear accident in the United States in 1979. But it said there was no need to expand the evacuation area beyond 30 km at this point.
- The head of the U.S. Nuclear Regulatory Commission, Gregory Jaczko, says it could take weeks to cool the reactors. About 300 workers, wearing masks, goggles and protective suits are toiling in the radioactive wreckage.
- Japan's nuclear agency said the radiation level at the plant was as high as 20 millisieverts per hour. The limit for workers was 100 per hour.
* Very low concentrations of radioactive particles believed to have come from Japan's Fukushima nuclear power plant have been detected on the U.S. west coast, diplomatic sources said on Friday. The level of radiation was far too low to cause any harm to humans, they said.
- G7 industrialised countries agreed, after a teleconference of finance ministers, on concerted intervention, the first since 2000, to restrain the yen, hoping to calm global markets.
The U.S. dollar surges two yen as far as 81.83 yen, leaving behind a record low of 76.25 on Thursday, after the Bank of Japan began to sell yen and other central banks agreed to intervene later. Japanese shares jump 2.72 percent, but were still down about 10 percent on the week.
- World Health Organisation believes the spread of radiation is localised and poses no immediate risk to human health. Millions in Tokyo remain indoors, though winds are likely to carry contaminated smoke or steam away over the Pacific Ocean.
- Airlines pull in extra, larger aircraft to help thousands of people leave. U.S. Homeland Security Secretary Janet Napolitano says passengers and cargo arriving from Japan will be checked for radiation. Other countries also begin screening.
- Nuclear crisis diverts attention from the tens of thousands affected by last week's earthquake and tsunami. About 320,000 households in the north without electricity in near-freezing weather. Death toll is expected to exceed 10,000.
(Tokyo bureau; Compiled by World Desk Asia)