Japan raises nuclear crisis level
Japan's nuclear safety agency has raised the severity rating of the country's nuclear crisis from Level 4 to Level 5, putting it on a par with the 1979 Three Mile Island accident in the United States.
Ryohei Shiomi, a spokesman for the nuclear safety agency, confirmed the rating for the Fukushima Dai-ichi nuclear crisis had been raised on the seven-level International Nuclear Event Scale.
The scale defines a Level 4 incident as having local consequences and a Level 5 incident as having wider consequences.
The hallmarks of a Level 5 emergency are severe damage to a reactor core, release of large quantities of radiation with a high probability of "significant" public exposure or several deaths from radiation.
A partial meltdown at Three Mile Island in Pennsylvania was also ranked a Level 5.
The Chernobyl accident in the Ukraine in 1986, which killed at least 31 people with radiation sickness, raised long-term cancer rates, and spewed radiation for hundreds of miles, was ranked a Level 7.
France's Nuclear Safety Authority has said it believes the crisis in north-eastern Japan should be ranked Level 6 on the scale.
Meanwhile, Japan's radioactive fallout has reached Southern California but first readings are "about a billion times beneath levels that would be health threatening," a diplomat said
The diplomat, who has access to UN radiation tracking, was citing readings from one of its California-based measuring stations.
The Comprehensive Test Ban Treaty Organisation does not usually make its data public.