As fear spreads in Japan, radiation expert Professor Gerry Thomas tells Channel 4 News: "We are panicking that poor, savaged population about radiation that is not going to harm them."

Anti-nuclear protestors in Manila (R)

As helicopters throw water onto the reactor at the Fukushima Daiichi nuclear plant, panic is spreading across across Japan and the wider world. The UK and the United States have chartered planes for people who want to leave the country and France is also advising people to either leave or head to southern Japan.

But some nuclear experts say that the risk of a radiation leak is being exaggerated. Professor Gerry Thomas is Chair in Molecular Pathology at Imperial College, London and an expert in radiation impact. She says that the precautions taken so far should be sufficient to protect people near the site, telling Channel 4 News: "There is no significant release of radiation yet, it's really only the workers that are at risk. We are not looking at an accident anything like Chernobyl. The Japanese have done everything by the book by removing people from the vicinity."

Gregory Jaczko, who heads the US nuclear regulator, disagrees. He told Congress that the public should get at least 50 miles away from the stricken plant. The Japanese cleared a radius of 12 miles.

The EU's energy chief Gunther Oettinger went further, telling the European Parliament: "There is talk of an apocalyspe and I think that word is particularly well chosen."

'Unhelpful response'

Professor Thomas says the response from foreign governments and the media is unhelpful: "I think it's totally irresponsible and one thing we should have learnt post-Chernobyl is not to spread panic and make claims that turn out to be wrong. The psychological damage being done now to the Japanese is huge. At Chernobyl we told local people that they would get cancer and die and they are still living with the fact that we gave them false information."

She believes misinformation about what happened at Chernobyl is partly to blame for the current panic: "The media has got Chernobyl so wrong it's unbelievable. At Chernobyl there was a massive release of iodine that shot high into the atmosphere and got carried on the wind. We are not likely to have anything like that in Japan.'

"Tens of thousands of people have lost their lives. Even if the worst case scenario happened and there was an accident ten times the size of Chernobyl, you wouldn't have as many deaths as that. We are missing the point here and we are panicking that poor, savaged population, about radiation that is not going to harm them."

On Wednesday, as people in Japan bought up supplies of potassium iodide supplements to protect their thyroid glands, radiation expert Professor Richard Wakeford told Channel 4 News that people were wasting their money: "This sort of panic-buying is entirely unnecessary. I can't believe the doses experienced in Japan at the moment could pose a serious risk in food and water."

Dr John Roberts, an expert on nuclear physics at the University of Manchester's Dalton Nuclear Institute, explains why this is not another Chernobyl.

"There are a great number of differences between the situation and Chernobyl. The situation in Chernobyl was a badly designed reactor with a very bad safety culture, due to isolation in the Soviet Union, they were not involved in regulatory issues. The design didn't prevent release in case of a core accident so when the accident happened it blew the top off the building.

"In Japan, initially all systems seemed to work very well after the earthquake struck. Seismic sensors shut down the reactor so power outlet was drastically reduced and diesel generators kicked in to replace the electricity power supply to the primary coolers. After the tsunami flooded the generators the battery kicked in for another 8 hours.

"What happened next is unclear but they were not able to keep the cooler connected to power. This may be where some of the fuel was partially exposed. As soon as steady water can be applied for a good length of time to the decaying fuel rods they will cool down.

"This radiation is not significant at a long distance and I don't think there will be an impact at the distance of Tokyo."

Fears over the radiation leak are having an impact across the world. China has signalled a possible halt to its nuclear power boom, suspending approvals for proposed nuclear sites and launching checks of plants already operating.

And public concern in Europe is forcing governments to follow China in announcing safety overhauls. Chancellor Angela Merkel has said she aims to accelerate Germany's move away from nuclear energy and has ordered the closure of all nuclear plants which began operating before 1980 for at least three months, while checks are carried out.

In an article for Channel 4 News, environmental psychologist Professor Nick Pidgeon writes about the fragile acceptance of nuclear power in Britain. He says that: "While many in Britain have indeed come to support nuclear power over the past decade they do so while viewing it only as a 'devil's bargain', a choice of last resort in the face of severe climate change."

"Germany alone shutting down reactors will add half a billion tonnes of CO2 into the atmosphere within a decade" Mark Lynas

But Dr Roberts says nuclear energy is one of the safest ways of generating electricity, telling Channel 4 News: "Over 40 years this is a very safe industry with extremely low fatality rates compared to other sources (of electricity). Reactors being built in the UK are much more modern and even safer than those which withstood a magnitude 9 earthquake. Reactor designs have multiple back up safety systems, that's why they are so expensive to build. The nuclear industry is very regulated and has a very good safety record."

What next for nuclear power?

Climate change activist and specialist Mark Lynas says the reaction is worrying. He told Channel 4 News that nuclear power is vital in order to curb carbon emissions: "Germany alone shutting down reactors will add half a billion tonnes of CO2 into the atmosphere within a decade"

He believes the reaction is misplaced. "There is no significant danger to anyone who is more than a kilometre away from the plant. This is getting close to public hysteria, the flames of which are being fanned by foreign governments evacuating their citizens in response to radiation increases that are so minimul they barely register against natural background levels."

He argues that nuclear power is the only way to provide energy and stop runaway climate change, saying: "I can't see any other short to medium term sources that will help us deal with global warming. If we don't use nuclear then we are guaranteed a higher use of coal and fossil fuels. And the risk from that is infinitesimally greater than the risk of radiation exposure.

"The imagery resulting from this, of facemasks and exclusion zones, and mentions of Chernobyl are guaranteed to bring back fears of radioactivity in general and that will be a tragedy for the world."