The nuclear plant was damaged on March 11 when Japan was hit by one of the greatest natural disasters ever recorded - a magnitude 9.0 earthquake, followed by a tsunami with waves over 10 meters, leaving more than 28,000 people dead and missing.
The damaged Unit 3 reactor at Fukushima Daiichi nuclear plant emits smoke, March 28, 2011 (Photo courtesy Japan's Ministry of Defense)
Tokyo Electric Power's Fukushima Daiichi nuclear plant went into automatic shutdown, but loss of power and emergency generators caused the cooling systems to fail, exposing nuclear fuel.
There are indications that fuel in the reactor cores of Units 1, 2, and 3 and some spent fuel pools have been damaged due to overheating. The high levels of radioactivity in the water leaks likely resulted from a partial meltdown of fuel rods, Japanese officials have said.
The company has been spraying sea water, and since Friday, fresh water, into the reactors to cool the fuel to prevent a meltdown, but government officials acknowledge that a partial meltdown has occurred in at least one reactor.
Water is sprayed from tanker trucks to cool the overheating nuclear fuel. (Photo courtesy Japan's Ministry of Defense)
"To keep the core of the reactors cool, they have to continue spraying water. If the core isn't kept cool the reactors could be damaged," Koji Okamoto, a Tokyo University professor who specializes in nuclear plant design, told NHK television. "And if that happens, there's a possibility that a huge amount of radioactive gas will be released into the air."
But if too much water is sprayed, Okamoto warned, "the water could leak out."
Little progress has been made in removing the radioactive water from the basements of the turbine buildings of the first three reactors. The water is thought to have come from the reactors' containment vessels. The amount may increase until workers determine where the water is coming from.
The plant's operator, Tokyo Electric Power Company, says it is likely that highly radioactive water in an underground tunnnel next to the Unit 2 reactor's turbine building has the same source as a puddle in the basement, but that source has not yet been identified.
The water seeping into a trench outside the Unit 2 reactor had a radiation level of more than 1,000 millisieverts per hour, TEPCO officials said, far above the 100 millisieverts per hour considered to be the lowest amount at which cancer risks are apparent.
The company is studying where to store the polluted water and how to remove the radioactive substances. But TEPCO officials have said they are not sure if the methods used in the past can treat the highly contaminated water.
A view of the damaged Fukushima Daiichi nuclear power plant (Photo courtesy TEPCO)
The utility says radioactive water in the Unit 1 reactor's trench may have been brought in by tsunami waves. The company says it will consider releasing the water in the Unit 1 reactor's trench into the sea if analysis shows that the water is safe.
High levels of radiation were found in the ocean near the plant this past weekend, but officials said it would be quickly diluted and posed no threat to human health.
Chief Cabinet Secretary Yukio Edano said Monday that TEPCO must increase monitoring of soil and water.
The head of the U.S. Nuclear Regulatory Commission Gregory Jaczko, arrived in Tokyo on Monday to meet with senior Japanese nuclear experts and health authorities and TEPCO officials. A team of experts from the NRC has been in Japan working to help resolve the crisis.
Lights are on again in the control room of the Unit 2 reactor at the Fukushima Daiichi nuclear plant. (Photo courtesy TEPCO)
Chairman Jaczko said, "Our nuclear experts are working closely with their Japanese counterparts, and we both continue to share expert analysis as we move forward to address this challenge. I reconfirmed in my meetings that we are prepared to provide any assistance we can in the days to come."
France says it will send three more nuclear experts to Japan to help with efforts to remove highly radioactive water from the troubled Fukushima Daiichi Nuclear Power Plant.
Two other French experts are already in Japan and holding talks with the plant operator, Tokyo Electric Power Company. Four of the five experts are from French-based AREVA, one of the world's biggest nuclear energy firms, and the other is from the French Atomic Energy Commission.
This is the first time that France, the world's second largest operator of nuclear plants, has sent nuclear experts to Japan.
French President Nicolas Sarkozy will visit Japan as chair of the Group of 20 nations on Thursday. He will meet Prime Minister Naoto Kan to discuss extending further technical assistance to help end the nuclear crisis.
Some progress was made at the power plant on Tuesday when lighting was switched on again in the control room of the Unit 4 reactor. Workers connected an external power source to the display panel of the first reactor's control room, allowing it to show the status of some equipment.
The most recent radiation measurements outside the 20 kilometer (12 mile) radius evacuation area are within both U.S. and Japanese acceptable levels.
Copyright Environment News Service (ENS) 2011. All rights reserved.