Fukushima Wants Burying Like Chernobyl

The last week's huge quake and tsunami driven a nuclear crisis, which has left at least 17,000 people dead or missing. Though France's Nuclear Safety Authority, has rates the Fukushima crisis at six on the scale.(AFP) this crisis was previously rated as local problem by Japanese authority. Now Japan has raised the alert level at its quake-damaged nuclear plant (Fukushima Daiichi) from four to five on a seven-point international scale of atomic incidents.

The UN says the battle to stabilise the plant is a race against time.

Japanese nuclear officials said core damage to reactors 2 and 3 had prompted the raising of the severity grade, reports BBC.

The 1979 incident at Three Mile Island in the US was also rated at five on the scale, whereas the 1986 Chernobyl disaster was rated at seven.

Gift of Chernobyl

Gift of Chernobyl

But they still hoped to solve the crisis by fixing a power cable to two reactors by today to restart water pumps needed to cool overheating nuclear fuel rods. Workers also sprayed water on the reactor 3, the most critical of the plant's six.

It was the first time the facility operator had acknowledged burying the sprawling 40-year-old complex was possible, a sign that piecemeal actions such as dumping water from military helicopters or scrambling to restart cooling pumps may not work, Reuters reports.

Chernobyl Nuclear Power Plant reactor meltdown(reactor no. 4)

"It is not impossible to encase the reactors in concrete. But our priority right now is to try and cool them down first," an official from the plant operator, Tokyo Electric Power Co, told a news conference.

That is little solace for about 300 nuclear plant workers toiling in the radioactive wreckage, wearing masks, goggles and protective suits with seams sealed off by duct tape to keep out radioactive particles. "My eyes well with tears at the thought of the work they are doing," Kazuya Aoki, a safety official at Japan's Nuclear and Industrial Safety Agency, told Reuters.

Even if engineers restore power at the Fukushima Daiichi plant, the pumps may be too damaged from the earthquake, tsunami or subsequent explosions to work.

The first step is to restore power to pumps for reactors 1 and 2, and possibly 4, by today, said Hidehiko Nishiyama, Japan's nuclear safety agency spokesman.

By tomorrow, the government expects to connect electricity to pumps for its badly damaged reactor 3 -- a focal point in the crisis because of its use of mixed oxides, or mox, containing both uranium and highly toxic plutonium.

Asked about burying the reactors in sand and concrete, Nishiyama said: "That solution is in the back of our minds, but we are focused on cooling the reactors down."

Burying the reactors would leave part of Japan off-limits for decades. "It's just not that easy," Murray Jennex, a San Diego State University in California professor said when asked about the so-called Chernobyl option to bury the reactors.

Cleaning operation of contaminant in Chernobyl

"They are kind of like a coffee maker. If you leave it on the heat, they boil dry and then they crack," he said. "Putting concrete on that wouldn't help keep your coffee maker safe. But eventually, yes, you could build a concrete shield and be done with it."

Enigma of Nuclear radiation of the Fukushima Daiichi plant reactors in Japan

The reactors at the Fukushima Daiichi plant are boiling water reactors. The reactor which saw the explosion is Fukushima Daiichi 1. It was connected to the grid in November 1970, making it about 40 years old. There are six reactors at the Fukushima Daiichi site, of which unit 1 is the oldest, according to the World Nuclear Association.

How does a nuclear reactor of this kind work?

Uranium 235 -- the fuel inside a nuclear reactor -- undergoes nuclear fission. This process emits a lot of heat energy which produces steam, and that steam turns a turbine, generating electricity.

What happened to the nuclear reactors during the quake?

Three of the six reactors at the site were in operation when the earthquake hit. The reactors are designed to shut down automatically when a quake strikes, and emergency diesel generators began the task of pumping water around the reactors to cool them down. However, these stopped about an hour later. The failure of the back-up generators has been blamed on tsunami flooding by the International Atomic Energy Agency (IAEA.)

Sea water injection was started on Saturday, but then paused after a tsunami warning, according to the plant owners Tokyo Electric Power Company.

What could have caused the explosion at the plant?

* Nuclear Energy

The blast was not caused by damage to the nuclear reactor but by a pumping system that failed as crews tried to bring the reactor's temperature down, Chief Cabinet Secretary Yukio Edano said Saturday. He said the plant operator confirmed there was no damage to the steel container housing the reactor.

Malcolm Grimston, Associate Fellow for Energy, Environment and Development at London's Chatham House, said he believed the explosion had been caused by a build-up of pressure inside the inner containment of the reactor.

"Because they lost power to the water cooling system, they needed to vent the pressure that building up inside.

"My suspicion is that as the temperature inside the reactor was rising, some of the metal cans that surround the fuel may have burst and at high temperature, that fuel cladding can react with water to produce zirconium oxide and hydrogen.

"That hydrogen then will be part of the gases that need to be vented. That hydrogen then mixes with the surrounding air. Hydrogen and oxygen can then recombine explosively.

"So it seems while the explosion wasn't directly connected with the nuclear processes, it was indirectly connected, because the hydrogen was only present because of what was going on in the reactor core."

What is a meltdown, and can it be avoided here?

Japan's nuclear agency said there was a strong possibility that radioactive cesium detected at the plant after the blast was from the melting of a fuel rod.

Robert Alvarez, Senior Scholar at the U.S. Institute for Policy Studies, explained that a meltdown could happen when the water surrounding the core of the reactor boiled or leaked away, leaving the fuel rods exposed, allowing temperatures to rise to up to 5,000 degrees Fahrenheit.

"The radiation is so intense it's impossible to deal with it. The control room would be uninhabitable," he said. "Without cooling, cladding surrounding the fuel can ignite, and the fuel itself start to melt.

"Then you have a huge amount of radioactive gases and particles, and if the primary and secondary containment fails, you have a large amount of radioactive gases escaping into the environment."

Whether a meltdown happens in this case depends on whether the pumping and cooling system can be restored in time, and whether if a meltdown starts, the secondary containment is strong enough to stay intact, according to Alvarez.

"If the pumping system is down there won't be enough pressure or water inside to cool the fuel rods down," he said. (ArticlesBase SC #4396654)