By MICHAEL S. JAMES, DANIEL ARNALL, CHRIS VLASTO and MATTHEW MOSK March 12, 2011 ( ABC NEWS )
The container protecting a nuclear reactor at a plant facing a possible meltdown was not damaged in an explosion that injured four workers and destroyed the exterior walls of the plant, a Japanese government spokesman said today.
Government Spokesman Yukio Edano said the blast did not damage the nuclear reactor itself at the Fukushima Daiichi, which would cause radioactive material to leak out.
Contrary to initial reports of radiation levels rising around the Fukushima Daiichi plant after the blast, Edano said that radiation is decreasing and that the pressure inside the reactor is also dropping.
"Based on this situation, we are concerned about the nuclear reactor and have decided to fill the reactor with seawater," Edano said.
But a top U.S. scientist said Japan must come to terms with the severity of the nuclear accident it is facing, and work to immediately protect its most vulnerable residents from the damage of radiation exposure -- particularly protecting children against exposure to radioactive iodine.
"Any attempt to make it seem that this is not the worst case imaginable is foolhardy," said Edwin Lyman, a senior scientist with the Union of Concerned Scientists.
Both the U.S. and France have plans in place to distribute doses of stable potassium iodine to children who live in the vicinity of a nuclear power plant in the event of a catastrophic radiation release. Lyman said he did not know whether Japan had similar plans in place.
If the reactor core melts through the steel vessel that is housing it, Lyman said, the risk Japan faces is a radioactive plume that could disperse tens or even hundreds of miles. "You could have large swaths of areas that will need severe remediation. And a lot of people exposed to radioactivity who will have an increased chance of cancer."
After the nuclear accident at Chernobyl, Lyman said there were over 6,000 cases of childhood thyroid cancers, and it was later determined if the children had taken stable iodine a few hours before being exposed to the radiation it would block the intake of the radioactive material in the thyroid. "That has been shown to reduce exposure significantly," he said.
The Fukushima Daiichi plant, located about 200 miles northeast of Tokyo, was one of two run by the Tokyo Electric Power Co. whose cooling systems were damaged in the 8.9 earthquake and tsunami that hit Japan Friday.
At least two reactors at the Daiichi plant and three at the Fukushima Daini plant which located about 10 miles away had damaged cooling systems, the Associated Press reported. Officials declared states of emergency for the five reactors.
Ryohei Shiomi with Japan's Nuclear Safety Commission said earlier that a meltdown was possible at the Fukushima Daiichi plant.
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Japanese TV images showed the crumbled remains of one of the plant building's walls with smoke emerging from the site.
An evacuation order was expanded from a 10-kilometer to 20-kilometers radius around the plant.
The majority of the 51,000 people living near the danger zone have been already evacuated, according to Shiomi.