The risk of a partial meltdown at a floundering Japanese nuclear power plant rose today as cooling systems failed at a third generator, potentially exposing its fuel rods, just hours after a second explosion at a separate reactor blew the roof off a containment building.
Japanese authorities are struggling to bring several damaged reactors under control three days after a massive earthquake and tsunami on Japan's northeast coast crippled the electricity that runs the cooling system for reactors.
Eleven people were injured in the blast, one seriously, officials said. It was unclear if radiation was released by today's explosion, but a similar explosion at another of the plant's reactors over the weekend did release radioactive material.
Yukio Edano, chief Cabinet secretary, said the release of large amounts of radiation was unlikely. Trace amounts could be released into the atmosphere, though, and about 500 people who remained within a 12-mile radius were told to temporarily take cover indoors, he said.
The two reactors where the explosions occurred are thought to have already suffered partial meltdowns, which can occur when radioactive fuel rods, normally underwater, remain partially uncovered for too long. The longer that the fuel is exposed, the closer the reactor comes to a full meltdown.
Now, technicians are fighting for time while the fuel gradually generates less heat. They are trying to keep the rods covered despite a breakdown in the normal cooling system, which runs on power from the electrical grid. The operators have been using a makeshift system for keeping cool water on the fuel rods ever since the earthquake knocked out power and the diesel generator later failed.
The incidents are putting incredible strain on Japanese nuclear officials and Tokyo Electric Power Co., the company that runs both struggling plants.
"I'm not aware that we've ever had more than one reactor troubled at a time," said Frank von Hippel, a physicist and professor at Princeton University.
"The whole country was focused on Three Mile Island," he said, referring to the 1979 nuclear plant accident in Pennsylvania. "Here you have Tokyo Electric Power and the Japanese regulators focusing on multiple plants at the same time" (Tabuchi/Wald, New York Times, March 14). -- AS
