Japan has raised its evaluation of the Fukushima Daiichi nuclear disaster to the highest level on the international nuclear accident scale - level seven. But Japanese Prime Minister Naoto Kan says things are getting better at the plant.
The upgrade makes Fukushima only the second nuclear accident ever to rank at level seven. The other was the 1986 Chernobyl disaster.
Hidehiko Nishiyama, an official with Japan's Nuclear and Industrial Safety Agency says, despite the similar rankings, the severity of the the two accidents is different.
Nishiyama says the amount of radiation released so far is only a tenth that of Chernobyl and there have been no radiation-related deaths in Japan.
Radiation is still coming out of the damaged Fukushima plant, but the levels measured in communities outside of a 20-kilometer evacuation area are slowly falling, each day.
Japanese Prime Minister Naoto Kan says based on that decline, the situation at Fukushima is getting better, step by step.
Kan says the reactors and spent fuel pools at Fukushima must be brought under control at all costs. He has asked Tokyo Electric Power for a plan on how it intends to do that.
Work was momentarily interrupted at the plant on Tuesday afternoon when a strong aftershock hit nearby. The magnitude 6.3 tremor was the third strong aftershock in 24 hours.
It caused workers to move into a safe area at the plant, but did not affect operations aimed at cooling and stabilizing the reactors.
A morning aftershock caused a small fire outside of the reactor building. It was quickly extinguished. A day earlier, water injection was temporarily interrupted by a tremor.
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