Desperation: Japan Now Using Seawater To Cool Damaged Reactor
March 12, 2011: Yuka Hayashi and Andrew Monahan / The Wall Street Journal – March 12, 2011
This is clearly an act of desperation and something that has never been attempted before in Japan, or elsewhere… – SJH
“Using seawater will destroy the reactor. Taking this step means they have given up all hope of recovering and repairing the reactor.” – Michael Rivero (WRH)
TOKYO—Japanese officials continued their battle to control a dangerous reactor overheating in the nation’s worst nuclear accident that followed Friday’s earthquake, as they resorted to an unprecedented attempt to cool the reactor with seawater.
Top government officials assured the nation Saturday evening that an explosion that took place at one of the reactors at the Tokyo Electric Power Co.’s Fukushima Daiichi nuclear-power plant earlier in the day merely knocked down the walls of its external concrete building, and that the reactor and the containment structure surrounding it remained intact.
“The latest explosion wasn’t of a kind that would come with a significant leakage of radiation,” Yukio Edano, the chief cabinet secretary, said at a news conference. “It’s our expectation that we can bring this nuclear-power plant under control, using this unprecedented step of filling the containment structure with seawater.” Boric acid will also be added to the salt water to fight a possible elevation in nuclear reaction, Mr. Edano said.
The building housing the stricken reactor collapsed Saturday afternoon with smoke billowing out, and officials responded by expanding the evacuation perimeter to a 12-mile radius and saying they were preparing to stockpile iodine supplies “just in case.”
Soon after the explosion, the radiation level outside the reactor became elevated to 1,015 microsievert—the equivalent of being exposed to the maximum allowable level for a full year in a single day. The level has since come down sharply. The explosion was caused by hydrogen leaking inside the containment structure from the reactor experiencing high vapor pressure, Mr. Edano said.
Three people waiting at a nearby high school campus at the time of the explosion were confirmed to have been exposed to radiation, NHK, the national broadcaster, reported. The exposure, it said, hasn’t affected their physical conditions. Some 90 people also at the site then—all to be evacuated from the proximity to the troubled power plant—may also have been exposed, it said.
Earlier in the day, Tokyo Electric took emergency measures to avert a meltdown of a stricken nuclear-power plant hit by the massive tsunami that followed Friday’s earthquake in the northeast region of Tohoku. Those steps appeared to be bringing down the dangerous pressures that had built up in the container, a Tokyo Electric spokesman said. But he and the government officials wouldn’t discuss in detail the progress they have made in lowering the temperature inside the reactor. The plant is located 150 miles away from Tokyo.
Previously, the utility had said there was a risk of a meltdown in the core after the quake cut off power to pumps providing cooling water. That, in turn, could lead to heating of the core, the risk of a meltdown, and the release of radiation. A portion of the reactor’s fuel rods, which create heat through a nuclear reaction, had become exposed due to tsunami-related cooling-system failure, a Tokyo Electric spokesman said.
“The size of tsunami caused by the latest earthquake far exceeded what we had previously assumed,” Prime Minister Naoto Kan said at a news conference Saturday evening. “We’ve had a backup system designed to kick in when a nuclear-power plant failed, but this time, there has been a problem with that system.”
Loss of cooling water resulted in a near meltdown of the Three Mile Island reactor in Pennsylvania in 1979, the worst nuclear incident in U.S. history.
At Fukushima Daiichi, the three reactors that were operating when the earthquake struck shut down as they were designed to do, but pressure built up inside them due to malfunctioning of their cooling system.
On Saturday, Tokyo Electric said another nuclear-power plant nearby, Fukushima Daini, was experiencing rises of pressure inside its four reactors. A state of emergency was called and precautionary evacuations ordered. The government has ordered the utility to release “potentially radioactive vapor” from the reactors, but hasn’t confirmed any elevated radiation around the plant.
The International Atomic Energy Agency said it is ready to provide assistance if requested. All other Japanese power companies operating nuclear-power plants said their facilities are operating normally.
Nuclear problems are particularly troubling in Japan, which has 56 nuclear reactors, providing about 20% of the nation’s electricity. Eleven reactors shut down as a result of the earthquake, as well as dozens of conventional fossil-fired or hydroelectric plants, leaving millions of people without electricity.
To cope with a severe power shortage expected to result from reactor shutdowns, Tokyo Electric on Saturday asked industrial customers to close or reduce their operations to save electricity and ensure supplies to households, a spokesman said.
When nuclear plants lose grid power, emergency on-site generation is supposed to furnish backup power. But some diesel generators at the Fukushima Daiichi plant failed a short time later due to the damage from the tsunami that followed the earthquake. That forced the plant to resort to batteries to furnish electricity to critical instrumentation and controls for at least one of the reactors, experts said.
Reactors at the plant use a special cooling system, called the Reactor Core Isolation Cooling system, to take waste heat and run some critical systems. But experts said even that system and batteries wouldn’t be able to furnish as much power as was needed, putting pressure on plant officials to quickly find additional sources of electricity.
Experts said that Tokyo Electric has improved its processes and communications since a July 2007 earthquake heavily damaged the Kashiwazaki-Kariwa nuclear plant, one of the world’s largest. The entire plant was shut down for 21 months following that quake, and some reactors still aren’t back in operation.
Tokyo Electric was criticized after the 2007 quake for secrecy concerning how it was responding to problems at the Kashiwazaki plant and for rejecting inspection and assistance offers from the IAEA, which is intended to create confidence in the way an emergency is handled.
The Kashiwazaki plant suffered from seismic activity, in the 2007 quake, that exceeded the level for which it was designed, calling into question seismic assumptions made by regulators and the plant operator. There was a radioactive release when water sloshed out of spent-fuel-cooling pools and spilled into the Sea of Japan.
BBC: The Seawater Solution At Fukushima
The Tonka Report Editor’s Note: It has now been confirmed by the Nuclear and Industrial Safety Agency (NISA) that a meltdown triggered the Fukushima reactor explosion in Japan… – SJH
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