Friday, March 11, 2011

Japanese nuclear reactor in peril

Japanese authorities and the U.S. military on Saturday were racing to find ways to deliver new backup generators or batteries to a nuclear power reactor whose cooling facilities have been crippled by a loss of power as a result of the earthquake.
The reactor, owned by Tokyo Electric Power Co., is currently drawing on battery power that may last only a few hours. Without electricity, the reactor will be unable to pump water to cool its hot reactor core, possibly leading to a meltdown or some other release of radioactive material.
Japanese authorities informed the International Atomic Energy Agency's Incident and Emergency Center that they have ordered the evacuation of about 3,000 residents within a 1.9-mile radius of the Fukushima Daiichi nuclear power plant, and told people within a 16.2-mile radius to remain indoors, according to the IAEA Web site.
The cooling problem is with the second of six reactors at the plant, located on the east coast of Japan about 200 miles north of Tokyo and south of the heavily damaged town of Sendai. Separately there were reports of elevated radiation levels inside the control room of one of the other reactor units, which was built 40 years ago. Sources said that the authorities were contemplating venting from that unit.
Altogether, 11 Japanese nuclear reactors shut down automatically as they are designed to do in case of an earthquake.
"The multi-reactor Fukushima atomic power plant is now relying on battery power, which will only last around eight hours," said Kevin Kamps, a specialist in nuclear waste at Beyond Nuclear, a group devoted to highlighting the perils of nuclear power. "The danger is the very thermally hot reactor cores at the plant must be continuously cooled for 24 to 48 hours. Without any electricity, the pumps won't be able to pump water through the hot reactor cores to cool them."
"There's a basic cooling system that requires power, which they don't have," said Glenn McCullough, former chairman of the Tennessee Valley Authority who has been keeping track of the situation in Japan. He said that as a result of the tsunami, water had gotten into the diesel generators that would otherwise have provided backup power.
In a statement that confused nuclear experts, Secretary of State Hillary Rodham Clinton said Friday morning that U.S. Air Force planes in Japan had delivered "coolant" to a nuclear power plant affected by the quake. Nuclear reactors do not use special coolants, only large amounts of pumped water.
"They have very high engineering standards, but one of their plants came under a lot of stress with the earthquake and didn't have enough coolant," she said, "and so Air Force planes were able to deliver that." It remained unclear what the Air Force had delivered.
Just hours after the quake, Japan's Nuclear and Industrial Safety Agency (NISA) declared a heightened state of alert at the Fukushima Daiichi nuclear power plant, according to the IAEA. NISA said that no release of radiation has been detected.
The evacuation comes after NISA said Friday that a fire broke out at the Onagawa nuclear power plant but was later extinguished.
The plant is about 45 miles north of the city of Sendai, which was badly damaged by the deadly earthquake and tsunami that hit Japan Friday afternoon. Sendai is the population center nearest the epicenter of the quake, and Japan's Kyodo News agency said that more than 200 bodies had been found so far near the city.
The key buildings in the Onagawa plant are about 15 meters above sea level, according to the Web site of Tohoku Electric Power, owner of the plant. The company said that was about twice the height of the previous highest tsunami.
Japanese authorities told the IAEA that that the Onagawa, Fukushima-Daini and Tokai nuclear power plants shut down automatically, and no radiation release has been detected. The plants have multiple nuclear reactors.
The IAEA said it is seeking details on Fukushima Daiichi and other nuclear power plants and research reactors, including information on off-site and on-site electrical power supplies, cooling systems and the condition of the reactor buildings. Nuclear fuel requires continued cooling even after a plant is shut down, the IAEA noted. "This is the most challenging seismic event on record, so it is a severe test," said McCullough. "Clearly the Japanese government is taking this very seriously."

No comments:

Post a Comment