⚠ Japan quake: Radiation warning after third blast ⚠

Prime minister Naoto Kan warned there is danger of more leaks and told people living within 19 miles (30 kilometers) of Fukushima complex to stay indoors to avoid exposure that could make people sick.

Around 70,000 people had already been evacuated from a 12-mile (20-kilometer) radius, and now about 140,000 remain in the new warning zone.

Chief Cabinet Secretary Yukio Edano urged: 'Please do not go outside. Please stay indoors. Please close windows and make your homes airtight.

'These are figures that potentially affect health. There is no mistake about that.'

As many as 800 non-essential staff have been evacuated from the Fukushima complex, while 50 workers remain to try to cool the reactors with water.

Professor John Beddington, the UK Government's chief scientific adviser, told the BBC Radio 4 Today programme: 'The reasonable worst case that can happen is that the cooling fails, the containment vessel is ruptured and they can't keep the temperature down.

'At that stage, the reactor is going to increase in temperature and you get meltdown. In that situation... that radioactive material is going to react with, for example, the concrete on the base of the reactor. That is likely to cause an explosion if that happens - and it is a big if.

'Even then, the sort of thing that would happen is we would get an explosion. It would put radioactive material up to about 500m...

'This would be a relatively small and short-term explosion, absolutely serious for the surrounding area, but I think that the exclusion zone of 20km, extending to 30km, is entirely appropriate.'

As the nuclear crisis deepened the official death toll topped 2,400 following the disaster on Friday.

There are still tens of thousands missing, and there are concerns some Britons may be among the dead.

There are so far no confirmed reports of British deaths, but around 17,000 UK nationals are known to have been in Japan at the time the quake hit.

The Foreign Office has urged any UK nationals who are in Japan to make contact and confirm that they are safe and well.

In a rare bit of good news, rescuers found a 70-year-old woman alive in her swept-away home in northeastern Japan four days after the tsunami struck.

Magnitude 9.0 Earthquake And Tsunami Devastate Northern Japan

OTSUCHI, JAPAN - MARCH 14: In this handout images provided by the International Federation of Red Cross Japan, A general view is seen of what is left of the city after a tsunami wiped away the gas station which caused a fire and burnt down the whole town, after an 9.0 magnitude strong earthquake struck on March 11, off the coast of north-eastern Japan, March 14, 2011 in Otsuchi, Japan. The quake struck offshore at 2:46pm local time, triggering a tsunami wave of up to 10 metres which engulfed large parts of north-eastern Japan. On Tuesday there was a third explosion from the Fukushima Daiichi nuclear power plant causing fears for the radiation levels being emitted from the plant. Japan have implemented a no fly zone for 30km round the reactors in order to stop any further spread of radiation.

More Japan quake: Radiation warning after third blast

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