By Achim Klüppelberg
On 11 March 2011, Japan’s east coast fell victim to the Tōhoku earthquake. The earth shook for several minutes, causing a huge tsunami, 370 km from Tokyo in the Pacific. As a consequence of both, earthquake and tsunami, several nuclear power plants suffered damage. The one most affected was Fukushima-Daiichi. In the course of the following days, three of six nuclear reactors suffered meltdowns. In reactor four, serious damage through hydrogen explosions occurred.
How was that possible? Japan is located in an area highly prone to earthquakes. In the past, there were multiple occasions on which earthquakes were followed by tsunamis, causing substantial damage to the built environment along Japan’s coasts. When building a nuclear power plant, designers and decision-makers, clearly, need to minimize the plant’s vulnerability to external events. A key question is how to do this when it comes to events that occur only once in a century, millennium, or every ten thousand years.
The reactors in Fukushima-Daiichi were constructed between 1967 and 1979. This was also the time when the Chernobyl nuclear power plant started to be built. In an effort to increase safety and in stark contrast to their Soviet counterparts, the Japanese designed their reactors with containments, which added a layer of protection against the unwanted spread of radionuclides. While the Soviet Union also built power plants in seismically active areas – notably in Armenia – the Japanese plants had higher standards when it came to anti-earthquake safety. All in all, the Japanese reactors were state-of-the-art facilities and with regard to safety on par with those in countries such as the United States, France or Sweden.
So what happened? In essence, safety considerations were not taking exceptional disasters of the scope of the March 2011 earthquake and tsunami into account. In other words, the magnitude of the earthquake and the height of the tsunami were simply greater than the maximum anticipated strain on the nuclear power plant. The plant operator, TEPCO, did not consider an earthquake of magnitude 9 to be a “credible event” in the Japan Trench, as the IAEA concluded in its 2015 report on the accident. TEPCO did not find it economically justifiable to invest in measures to protect the plant against such an event. As NUCLEARWATERS project leader Per Högselius writes in a forthcoming article, the company did consult historical earthquake and tsunami reports, but the conclusion was that although immense tsunamis did occur from time to time along the coast, no tsunami higher than 5.7 meters had ever been recorded in the particular stretch of coast where the Fukushima NPP was located.
Soon, a Japanese parliamentary panel declared that the disaster was not only a natural one. It was also a human-made one, because official institutions believed that measures taken were sufficient and that the cost-safety calculations were appropriate. This is correct, since humans created this envirotechnical system, in which the nuclear power plant was integrated into the waters of the Pacific Ocean.
Environmental historian Sarah Pritchard (Confluence) takes inspiration from Charles Perrow’s normal accident theory and Thomas P. Hughes analyses of technological systems. Following these scholars, accidents inevitably happen in complex human-made systems. The creation of the nuclear technological system, of which Fukushima-Daiichi was part, embedded high-risk large-scale technology into an environment prone to natural disasters. Pritchard argues that the Tōhoku earthquake and the ensuing tsunami did not rupture the envirotechnical system between the power plant and the Pacific Ocean, but instead altered it. Water is still being used as a coolant, only this time the reactor has emitted radioactive substances into the sea.
For Pritchard, both the nuclear station and the aquatic system are still bound to and interwoven with each other. This becomes clear when studies find tritium in the groundwater, showing that the envirotechnical system extends beyond the obvious connection to the Pacific. This further leads to the question of how to deal with the accumulating nuclear waste from the plant, much of it in the form of contaminated water stored in tanks on site.
For TEPCO water was both a saviour that made it possible to re-establish cooling of the molten reactor cores and a medium of contamination at the same time. Currently, the operator struggles with securing the rests of the destroyed reactor cores and storing them somehow safely on land. Radioactivity prevents a lot of the decommissioning work. The reactor cores need permanent cooling to prevent further uncontrolled nuclear reactions. Due to the initial destruction of the cooling circuits and the following makeshift replacements, water was not kept within and reused as coolant, as it leaked into the reactor building. From there, it was pumped out, treated and stored outside the plant. On several occasions, it was ultimately dumped into the Pacific. At the time of writing, no end to this problem is in sight.
In connection with the ten-year-anniversary of this tragedy, I was interviewed by the local Greenpeace Group Gießen, Germany. We discussed issues of safety, the current situation at Fukushima and the exciting question of whether nuclear energy could be useful in the context of the current climate crisis.
The interview can be watched here.
This year, we will also commemorate the 35th anniversary of the Chernobyl disaster. Therefore, it makes sense to reflect upon the role that nuclear energy plays in global and European energy supply. This is even more true in view of the fact that the nuclear industries in France, Britain, Sweden and other countries face tough decisions whether or not to reinvest into the aging nuclear infrastructure, the alternative being renewable energy sources.