Overwhelmed: Tokyo Electric Power Company Managing Director Akio Komiri cries as he leaves after a press conference in Fukushima

UK Mail Online

By David Derbyshire

 The boss of the company behind the devastated Japanese nuclear reactor today broke down in tears - as his country finally acknowledged the radiation spewing from the over-heating reactors and fuel rods was enough to kill some citizens

Japan's Nuclear and Industrial Safety Agency admitted that the disaster was a level 5, which is classified as a crisis causing 'several radiation deaths' by the UN International Atomic Energy.

Officials said the rating was raised after they realised the full extent of the radiation leaking from the plant. They also said that 3 per cent of the fuel in three of the reactors at the Fukushima plant had been severely damaged, suggesting those reactor cores have partially melted down.

After Tokyo Electric Power Company Managing Director Akio Komiri cried as he left a conference to brief journalists on the situation at Fukushima, a senior Japanese minister also admitted that the country was overwhelmed by the scale of the tsunami and nuclear crisis.

He said officials should have admitted earlier how serious the radiation leaks were.

Chief Cabinet Secretary Yukio Edano said: 'The unprecedented scale of the earthquake and tsunami that struck Japan, frankly speaking, were among many things that happened that had not been anticipated under our disaster management contingency plans.

'In hindsight, we could have moved a little quicker in assessing the situation and coordinating all that information and provided it faster.'

Nuclear experts have been saying for days that Japan was underplaying the crisis' severity.

It is now officially on a par with the Three Mile Island accident in Pennsylvania in 1979. Only the explosion at Chernobyl in 1986 has topped the scale.

Deputy director general of the NISA, Hideohiko Nishiyama, also admitted that they do not know if the reactors are coming under control.

He said: 'With the water-spraying operations, we are fighting a fire we cannot see. That fire is not spreading, but we cannot say yet that it is under control.'

But prime minister Naoto Kan insisted that his country would overcome the catastrophe

'We will rebuild Japan from scratch,' he said in a televised speech: 'In our history, this small island nation has made miraculous economic growth thanks to the efforts of all Japanese citizens. That is how Japan was built.'

It comes after pictures emerged showing overheating fuel rods exposed to the elements through a huge hole in the wall of a reactor building at the destroyed Fukushima nuclear plant.

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Radiation is streaming into the atmosphere from the used uranium rods at reactor number four, after a 45ft-deep storage pool designed to keep them stable boiled dry in a fire.

Boiled dry: This shot shows of the inside of reactor number four at the Fukushima nuclear plant before the disaster. The spent fuel storage pool is seen at the front of the shot. The rods are at the bottom of the pool, which has now boiled dry

However they say it will not be dangerous when it reaches our shores while low levels of radiation have already hit Southern California.

A UN official said the radiation reaching America is 'about a billion times' beneath health-threatening levels.

An airborne plume of radiation is expected to be swept towards Europe, and again officials stress that the levels reaching the UK will not be high enough to pose any risk to human health.

Lars-Erik De Geer of the Swedish Defence Research Institute, said particles would eventually be detected across Europe.

'It is not something you see normally,' he said. 'But it is not high from any danger point of view. It is only a question of very, very low activities so it is nothing for people to worry about.'

The prediction that particles could reach Britain within two weeks is based on previous data, gathered by scientists observing nuclear testing in China.

Meanwhile,  workers at the devastated power station are continuing their desperate battle to prevent a complete meltdown which some fear could be as bad as Chernobyl.

The latest pictures show a whole wall missing from the building housing reactor number four. Inside, a green crane normally used to move spent fuel rods into the storage pool can be seen. Underneath the crane, but not seen in the picture, is the 45ft-deep spent fuel storage pool which has boiled dry.

Officials at Fukushima are rapidly running out of options to halt the crisis. Military trucks are spraying the reactors for a second days with tons of water arcing over the facility.

Engineers are trying to get the coolant pumping systems knocked out by the tsunami working again after laying a new power line from the main grid.

And they today admitted that burying reactors under sand and concrete - the solution adopted in Chernobyl - may be the only option to stop a catastrophic radiation release.

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.   

'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.   

But some experts warned that even the concrete solution was not without risks.

'It's just not that easy,' Murray Jennex, a professor at San Diego State University in California, said when asked about the so-called Chernobyl option for dealing with damaged reactors, named after the Ukrainian nuclear plant that exploded in 1986.   

'They (reactors) 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.'   

And Yukiya Amano, the head of the U.N.'s International Atomic Energy Agency said workers were in a 'race against the clock' to cool the reactor.

Attempts to quell the overheating plant with waterbombs from helicopters yesterday failed and despite the army pelting the site with water cannon, radiation levels rose higher.

Engineers are also working to restore power to the coolant pumping system knocked out by the tsunami.