Japan has raised the severity rating of its nuclear crisis from level five to the highest level, seven. The 1986 Chernobyl disaster is the only other time a nuclear emergency has been given a level seven. This decision reflects the total release of radiation at the damaged Fukushima Daiichi power plant, which is ongoing, rather than a sudden deterioration. Reporting from Tokyo is Keith Bradsher, reporter for The New York Times. The Japanese government says that the total amount of radiation is 10 percent of what was released at Chernobyl and there's still nervousness in the country, says Bradsher.