The nuclear crisis in Japan continues to get worse. After an explosion at reactor 2 at the Fukushima power station and a fire (now extinguished) at reactor 4, radiation from the plant has reached harmful levels. Everyone within 30 kilometres of the danger zone has been told to stay indoors, and a no-fly zone has been imposed around the power station.
The prime minister, Naoto Kan, has warned: "Radiation has spread from these reactors and the reading of the level seems high . . . There's still a very high risk of further radioactive material coming out." The plant's operator, the Tokyo Electric Power Co, reported dose rates of up to 400 millisieverts per hour – eight times the legal limit for exposure in one year.
But as several scientists have reminded us this morning, this is not another Chernobyl. The four damaged reactors at the Fukushima plant were shut down automatically when the earthquake was detected. In Chernobyl, by contrast, the reactor exploded while operating at full temperature, with the result that far greater levels of radioactive material were released.
Despite this, the Fukushima accident has already prompted a rethink in several European countries not renowned for their large earthquakes. In Germany, Angela Merkel, who reversed the popular SPD-Green pledge to phase out nuclear energy by 2022, has announced a "three-month moratorium" on plans to renew 17 power stations. In other words, the Japanese catastrophe has provided Merkel with the political cover necessary to drop an extraordinarily unpopular policy (88 per cent of the public want all plants closed).
Germany isn't alone. Switzerland, another country not known for its high levels of seismic activity, has suspended the approvals process for three new nuclear power stations.
In Italy, where large earthquakes are more common, plans to introduce nuclear energy by 2013 are now in doubt. But it's notable that the US, where eight plants are located on the earthquake-prone West Coast, has offered a robust defence of nuclear power. Yet as the New York Times noted: "most of the nuclear plants in the United States share some or all of the risk factors that played a role at Fukushima Daiichi: locations on tsunami-prone coastlines or near earthquake faults, ageing plants and back-up electrical systems that rely on diesel generators and batteries that could fail in extreme circumstances."
Given the uncertain outcome of events in Japan, other countries, including Britain, are suspending judgement. The twin challenges of energy security and climate change have bolstered the case for nuclear power in recent years. The long-term consequences of any decision to change course deserve serious consideration.