If a caldera eruption were to occur in proximity to the Fukushima Daiichi Nuclear Power Plant, the consequences would be nothing short of catastrophic. The volcanic ash would not merely fall upon the surrounding regions of Fukushima, obstructing the cooling mechanisms of the nuclear reactors, but the fusion of radioactive materials with the ash would exacerbate the risk of widespread dispersion. In such a scenario, it is highly probable that nations across the Northern Hemisphere would face direct repercussions, rendering them far from unaffected.
Dispersal of Radioactive Materials
Should a nuclear accident transpire, radioactive substances such as iodine, caesium, and strontium would be released into the atmosphere, and owing to prevailing wind patterns and atmospheric conditions, these materials would disperse over vast expanses. With strong winds or atmospheric disturbances in play, radioactive substances could travel hundreds of kilometres. In the most extreme of circumstances, the effects could reach across the entire Northern Hemisphere, with regions experiencing high concentrations of radiation potentially being impacted even thousands of kilometres from the source. The IAEA’s reports have outlined the trajectory of radioactive materials and the influence of meteorological conditions on such dispersion (source: IAEA, Preparedness and Response for a Nuclear or Radiological Emergency, 2011).
The Scope of Impact
In the aftermath of the Chernobyl disaster in 1986, radioactive materials were carried throughout Europe and North America due to prevailing winds. Within mere days of the incident, radiation spread to regions thousands of kilometres away, with particularly severe effects in Russia, Ukraine, Belarus, and parts of Western Europe. Thus, in the worst-case scenario, radioactive materials could be dispersed across the entire Northern Hemisphere, leading to widespread contamination and severe radiation exposure.
Risk of Acute Radiation Exposure
As radioactive materials spread over such vast distances, the risk of acute radiation exposure becomes alarmingly significant, particularly for neighbouring countries or even distant continents. If radiation were to descend in concentrated doses, regions exposed to over several hundred millisieverts could witness residents suffering from acute radiation sickness, manifesting as nausea, vomiting, diarrhoea, and immune system deficiencies. According to IAEA guidelines, health effects become apparent with exposure to more than 100 millisieverts of radiation (source: IAEA, Safety of Nuclear Reactors, 2018), and in the direst of circumstances, these effects could manifest over vast swathes of the globe, leading to extensive health consequences across the Northern Hemisphere.
The Risk of Caldera Eruptions in Japan
Japan, an archipelago blessed with many active volcanoes, faces an especially dire risk from caldera volcanoes, capable of causing catastrophic damage. Historical records reveal frequent caldera eruptions, particularly in the Kyushu region, where the Aso and Kikai calderas pose significant risks of re-eruption. Furthermore, caldera volcanoes are also found in the Tohoku and Hokkaido regions, where large eruptions have occurred in the past.
Indeed, the caldera risk in the vicinity of the Fukushima Daiichi Nuclear Power Plant epitomises the “gray rhino” phenomenon.
The “gray rhino” metaphor, coined in the work The Gray Rhino: How to Recognize and Act on the Obvious Dangers We Ignore (2016) by economist Michele Wucker, explores the theme of how societies tend to overlook imminent and conspicuous risks—represented by the “gray rhino”—until they become insurmountable crises. She underscores the challenge of recognising and responding to unavoidable dangers that we too often ignore (source: Michele Wucker, The Gray Rhino: How to Recognize and Act on the Obvious Dangers We Ignore, 2016).
According to research conducted by Professor Yoshiyuki Tatsumi and Associate Professor Keiko Suzuki at the Graduate School of Science, Kobe University, the likelihood of a caldera eruption of significant magnitude within the Japanese archipelago in the next century is approximately 1% (source: Kobe University, KOBE-U.AC.JP).
This study was published in the Proceedings of Japan Academy, Series B, Physical and Biological Sciences on November 11, 2014 (source: Kobe University, KOBE-U.AC.JP).
For further details on this research, please refer to the press release by Kobe University.
Long-Term Management of Radioactive Waste
Amid the ongoing decommissioning of the Fukushima Daiichi Nuclear Power Plant, the management of radioactive materials with exceptionally long half-lives, such as Plutonium-239 (Pu-239), over an astonishing period of approximately 24,000 years, presents an unfathomable challenge. Within this vast timespan, humanity will inevitably face numerous natural disasters and unforeseen risks. The caldera eruption risk surrounding Fukushima Daiichi stands as the quintessential embodiment of the “gray rhino.”
Should such a massive caldera eruption transpire, the resultant volcanic ash and radioactive materials would merge, dispersing contamination over vast territories. Were this risk to materialise, the management of the radioactive waste at Fukushima Daiichi would become all the more challenging, triggering further health risks and environmental repercussions. This scenario would only serve to underscore the complexity and difficulty of managing safety over the long term, placing a profound and enduring responsibility on future generations across millennia.
Thus, risk management surrounding Fukushima Daiichi is not merely a contemporary issue but a monumental responsibility extending far into the future, encompassing multiple generations and demanding our collective foresight and action.