The events unfolding at the Fukushima Daiichi nuclear plant are already worse than any worst case scenario could have predicted. Three reactors are thought to be damaged, but no one knows how badly, because the tsunami knocked out most of the instruments that would have allowed operators to read, among other things, water levels. With the roofs blown off by hydrogen explosions, there is increasing concern over the spent fuel pools inside the secondary containment shells. The spent fuel, recently discharged from the reactor cores, is hot and extremely radioactive. If the fuel disintegrates (or ‘melts’) because of insufficient cooling, there is a chance that it could reach criticality, either inside the core or in the spent fuel pools. In other words, a self-sustaining nuclear chain reaction could start, and fires could spread the radioactivity far and wide – depending on wind and weather conditions, possibly beyond Japan.
If operators manage to reconnect the station to an external power supply, they should be able to tackle the cooling problem, assuming enough of the auxiliary equipment is still functioning. But months, even years of mitigation work lie ahead. This is now probably the best case scenario.
The only points of comparison for most people are the disasters at Three Mile Island in 1979 and Chernobyl in 1986. In the public mind, they are vague memories at best and, at worst, distorted caricatures. On the 7-level International Nuclear and Radiological Events Scale, a tool developed in 1989 by experts from the International Atomic Energy Agency and the OECD’s Nuclear Energy Agency, Three Mile Island was rated level 5 (‘accident with wider consequences’) and Chernobyl level 7 (‘major accident’). Journalists and analysts alike have been clinging to the scale and the use of it to classify the Fukushima event (the figure has been revised repeatedly) as if these numbers meant something under the rapidly developing circumstances.
The situation at Fukushima Daiichi is starting to make the events at Three Mile Island look rather harmless. But it isn’t anything like Chernobyl: the reactors at Fukushima were successfully shut down before their cores started melting, the reactor designs are entirely different, and the amount of radioactivity released so far has been much more limited. From a technical point of view then, Fukushima is nowhere near as bad as Chernobyl.
From a strictly organisational perspective, however, it’s already much worse: there, you had one reactor to deal with; here you have three – so far. There, you had a huge army of conscripts and a government that recruited (‘volunteered’) hundreds of thousands of ‘liquidators’ to help mitigate the disaster; here, you have a company struggling to round up 100 workers. And, finally, evacuating the affected areas and establishing a 30 kilometre exclusion zone around Chernobyl was no doubt traumatic for the people involved, and a blow for Ukraine’s agriculture, but considering the vast size of the Soviet Union it was at least feasible in principle. Japan is small and densely populated. Where would all the people go, and how would they make up for the lost arable land?
It’s too early to say what lessons can be learned from Fukushima, including what the disaster may mean for the future of nuclear power. No doubt the blame game will begin soon, and proponents of both sides of the debate are marshalling their arguments. It will be important to remember that uncertainties are an intrinsic part of all sophisticated modern technological systems, whatever the risks we anticipate and the safety measures we put in place. In the face of climate change, a growing world population and an increasing demand for energy, doing our best to avoid disaster may not be enough: we must also prepare to deal with it.