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Navigating nuclear complexity – a scientist’s take on the Fukushima disaster

Navigating nuclear complexity – a scientist’s take on the Fukushima disaster

by Robert Martin-Short

Robert attended the British Science Festival 2013 as part of the British Science Association student bursary scheme.

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The first thirteen years of the 21st century have seen more than their fair share of earthquake disasters; Sumatra 2004, Sichuan 2008 and Haiti 2010 to name just a few. The aftermath of the magnitude 9.0 Tohoku earthquake on 11th March 2011 thus represents yet another example of the challenges the growing human population faces here on our restless planet.

Japan was – and still is – undoubtedly the most earthquake-prepared nation on earth, but the sheer scale of this event and the tsunami that followed proved beyond what had been planned for. The result was a death toll of almost 16,000, the destruction of 130,000 buildings and, of course, a nuclear incident that held the world’s attention for months.

Given this background, it was unsurprising to see the talk entitled “Fukushima two years on: The real story” so popular. Our speakers Paddy Regan and Stephen Judge – both nuclear physicists with experience of the disaster – were greeted by a packed lecture theatre containing a varied audience of both young and old, who listened intently to what they had to say.

Just a glance at its vast Wikipedia page will tell you that the Fukushima disaster is huge and complex subject, so I was keen to discover how the speakers would approach it and what they would focus on.

I guess we all know the basic story: Following the quake, the plant shut down and emergency generators came on to keep the coolant water circulating through the reactors, which remained hot due to radioactive decay. However, shortly after the quake the site’s defences were overtopped by a 14 metre high tsunami, which destroyed the emergency generators and left the reactors powerless.

Without power to operate the coolant systems, the fuel rods began to overheat and a cascade of failures resulted. All this and some general background to nuclear fission was described in the first talk. Nothing too new here, but it sets the scene.  

When I think of Fukushima on the news, images of explosions and radiation plumes spring immediately to mind. These explosions, Paddy explained, were caused by the build-up of hydrogen gas created by a high temperature reaction between the zirconium fuel-rod casing and water within the reactors. In fact, even before the explosions, some of this hydrogen had been intentionally vented into the atmosphere in order to reduce the pressure inside the cores.

Although they did release radioactive material into the atmosphere, these explosions did not break open the reactor cores as occurred at Chernobyl. Even so, this sounds like a dire situation – three crippled reactors and a cloud of radioactive material spreading over Japan. But how serious were the risks, and might they have been exaggerated? I think this question above all others was what this lecture was seeking to address.  

Confusion, worry and panic. From what we heard these seemed to be the three major responses to the disaster, not just from the public but also from certain authorities and the international media.

Nuclear radiation is truly frightening, not least because it is invisible and poorly understood by the public, but also because there is no agreeable ‘safe’ exposure value short of the statement “the more, the worse”. Indeed, it wasn’t long before traces of caesium 134 and caesium 137 - two of the most dangerous radioactive isotopes released from Fukushima Daiichi - were being detected in food produced in the prefecture, in the urine of Japanese children and as far afield as Vancouver. However, a point stressed again and again by Stephen and Paddy was as follows: Nuclear radiation is all around us, and levels of radiation outside the exclusion zone around Fukushima Daiichi are still several times below natural levels in many parts of the world – France, Switzerland and Germany to name just a few. Additionally, thanks to the atmospheric testing of nuclear bombs in the 1950s and 60s humanity has been irradiating itself with Cs-134 and Cs-137 for some time now – something that, said Paddy, would certainly bemuse alien scientists.

Statistically, it is true that one’s chances of contracting cancer increase with radiation dosage, but for the dose increase experienced by the people of Fukushima the increase in the chance of cancer is so diminishingly small that it is certain to be overwhelmed by other factors – namely lifestyle choices.

In light of this, Stephen made an important and thought provoking point at the close of his lecture; despite the dramatic images of exploding reactor buildings, the stories of evacuations of Tokyo and the fear of radioactive contamination, the Fukushima disaster pales in comparison to the destruction wrought by the tsunami. We would do well to remember this.

In my humble opinion, the Fukushima disaster was indeed a serious incident that threatened lives and pointed to serious failures in the disaster preparedness of its operator. Undoubtedly it could have been worse, but the true effects of the radiation released will probably be minor, especially when viewed in the context of the tsunami that caused it. We are right to fear radiation, but not irrationally so and certainly not to the extent that it drives us to despise nuclear power in general – something that should, in my opinion, be an important part of the world’s future energy mix.

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