In 2011, the shores of Japan were shaken by a 9.1 magnitude earthquake that spawned a 14 metre-high tsunami, flooding the reactors of the Fukushima Daiichi nuclear plant. Within four days, the loss of reactor core cooling led to nuclear meltdowns, hydrogen explosions, and contaminations in all three of the operational units. This released over 1,320 tonnes of nuclear waste into the surrounding area.
In late 2020, Yoshihide Suga, the new Japanese prime minister, put forward plans to dump the radioactive water produced by the disaster into the sea, as the tanks used to store the waste will run out of capacity in 2022. Every day, the plant generates 170 tons of radioactive wastewater, currently totaling 1.2 million tons. This has started to raise concerns, especially as some 100 million tons of radioactive matter were leaked in 2014.
What is nuclear energy and why is this waste produced?
The purpose of nuclear reactors is to transfer the energy gained by nuclear fission to steam, using it to spin turbines to produce electricity. A neutron is fired at an atom, which then fissions into smaller atoms and more neutrons. Some of these neutrons hit other atoms with sufficient energy to spark another fission reaction, releasing more neutrons. Over time, this causes a chain reaction in which the cycle repeats itself. These chain reactions release lots of energy as heat. This is removed from the reactor core by a fluid, often water, preventing the system from overheating while transferring the energy to the turbines in the form of steam. In order to maintain a steady chain reaction, control rods, often made from boron, are used to absorb excess neutrons. The spent fuel rods, which provide the ‘fuel’ for this radioactive decay, break down from uranium-235 to plutonium, which is highly radioactive. This is the usual nuclear waste that is produced and must be discarded. Moreover, the fission often causes other particles to form, such as radon or thorium, which also pose a radioactive threat.
In the worst-case scenario, when cooling systems fail and the uranium overheats, nuclear power plants can find themselves with a nuclear meltdown. The uranium-235 releases radioactive vapours which mix with the surrounding gases. In many cases, the gases contain high proportions of hydrogen, making them very flammable. This poses a risk, as when the gas pressure is too high, it can break containers and release nuclear radiation into the surrounding area. In many cases, the high pressure, combined with the high temperature, leads to a hydrogen explosion that spreads the radiation very far. This is what happened at Chernobyl in 1986, the most serious nuclear disaster in history. In the aftermath, there was a lot of tritium and carbon-14 released. In high concentrations, they can be very dangerous and make land uninhabitable.
Dealing with Fukushima’s radioactive waste
The public’s fears concerning nuclear disasters and waste are now focused on Fukushima Daiichi. The task before the Japanese government and climate scientists is how the lasting nuclear waste and damage caused by these accidents can be regulated and controlled. One solution would be to evaporate off radioactive water, as was done at the 1979 Three Mile Island accident. This evaporates off any water while concentrating all the radioactive components of waste, which are then stored in more compact ways, mostly on the site of the reactors. However, the Japanese government has rejected this proposal, as the concentration of radioactive material is too high and poses a health risk to people in the near area, potentially causing gene damage or DNA mutation.
Another response is to dilute the wastewater to 1/40 of its original concentration and release it into the oceans. This is what is currently being proposed for the wastewater present at the Fukushima plant. The Japanese government says that the vast majority of tritium, the radioactive component in nuclear wastewater, is naturally produced and that living bodies are already accustomed to low levels of radiation, so the addition of this waste to the ecosystem would not have much of an impact. This is further supported by some scientists, such as a report by the International Atomic Energy Agency in April 2013. Many experts have pointed to the fallout already existent within the oceans as a result of hydrogen bomb testing. Therefore, since the radioactive activity of cesium-137 in the North Pacific is estimated to be around 100,000 TBq, the 0.1 to 0.9 TBq added by the Fukushima water is unlikely to make a large impact.* Moreover, many natural rocks contain high levels of radioactive material.
Opponents of this policy claim that it poses a great danger to the marine ecosystems and people surviving off of them. A recent Greenpeace report outlined that there are ‘dangerous’ levels of the radioactive isotope carbon-14 in the water used to cool the reactor. This is worrying as the isotope has a half-life of 5,370 years and can become incorporated into living matter. It could build up in especially high concentrations in fish, hence posing a threat to human DNA if consumed. This is especially problematic for fishing and international relations. The local fishermen have spoken out, especially since neighbouring countries banned fish imports from the region after the 2011 meltdown. In addition, the South Korean government has voiced concern, claiming that the water would represent a grave threat to the marine environment, threatening to put further stress on an already tense relationship.
Overall, nuclear power is a tremendous source of energy that can cause great harm or good depending on whether it is harnessed properly. As shown in the case of Fukushima, accidents can have long-lasting consequences and impacts far beyond their vicinity. This serves as a stark reminder of the lack of international cooperation and consensus exhibited in such globally important issues, noting that collaboration is necessary to deal with these issues and prevent them from recurring in the future.
*TBq is an abbreviation for terabecquerel. This is the SI unit for radiation, where 1 becquerel corresponds to an activity of 1 nucleus decaying per second.
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