A few days ago, and shortly before leaving his post, Yoshiaki Harada, former Minister of the Environment of Japan, announced that by the year 2022 there will be no more space to store contaminated water from the Fukushima nuclear power plant and that it will probably be necessary to ‘throw it into the sea and dilute it’. Although Harada stressed that it is simply his opinion, and that there is still more discussion on the issue, the truth is that currently dumping into the ocean seems the only viable option for Japan.
Where does the radioactive water come from?
After the earthquake in 2011, a huge tsunami originated that ended up damaging the Fukushima nuclear power plant and damaging several of its reactors, which now need constant cooling to avoid explosions. As a result of the damage, the reactor walls are no longer airtight, and therefore this water is contaminated. On the other hand, after the accident there were also leaks of underground water under the reactors that mixed with radioactive material and was also affected.
The water is stored in large tanks with the aim that time passes and the radioactive activity of the pollutants decreases, but the amount generated is such that the storage capacity has been exceeded, so Japan has to look for alternatives since It is estimated that in three years there will be no space to store more water.
Why is there so much talk about tritium?
As Begoña Quintana, a researcher at the Ionizing Radiation Laboratory at the University of Salamanca, explains, “ these waters have already been treated with resins and various chemical processes that manage to eliminate many of the radionuclides they contain. Most are relatively easy to remove, with the exception of tritium. “
This happens because tritium is a radioactive isotope of hydrogen, an element that is part of the water molecule itself. “There are some electrolytic-type processes that do allow you to concentrate the water molecules that contain tritium, but they are carried out in laboratories, on a much smaller scale,” says the researcher. But, in this case, the amounts of water to be treated are of such magnitude that this procedure is probably not feasible.
With regard to the effects of tritium, we are talking about a radioactive isotope with a half-life of about twelve years, a relatively short period of time, in addition to not having a very high energy, so it is not one of the most dangerous isotopes. “In reality, controlled tritium discharges are made very frequently, but always in very low quantities,” Quintana explains. The problem here, the expert points out, will occur at the local level: “the fish and aquatic plants in the environment in which the tritium water is poured will assimilate and concentrate the tritium, and the thresholds above which it will surely be exceeded. a food is considered unfit for consumption. With regard to radioactive contamination, the policy is to minimize the risk, so these thresholds are very low ”, explains the researcher.
“That is a very local effect. At a global level, we are talking about the sea having millions of tons of water, obviously that is going to end up being diluted and the risk is minimal. The main problem here is for Japan and the surrounding countries ”. Due to this, the fishing sector in the Fukushima area, already very affected by the disaster, is going to have an added problem by not being able to commercialize the fish for a while, and this is the reason why fishermen have criticized the minister’s proposal. According to the newspaper El País, only two years ago fish auctions were resumed in the area, and even so sales are 20% below pre-disaster levels.
“What does seem clear is that the scope of radioactive contamination would be very short and very specific. From the moment of emission, the water would begin to be diluted in the ocean, therefore, at a local level it would be problematic, but not at a global level ”, Quintana clarifies.
The problem of contaminated water is not new
Despite everything, many voices are suspicious of the decision to dump the contaminated water from Fukushima into the sea. “Actually, this is not a new issue, since the accident took place we have a continuous problem with the discharge of radioactive water into the sea,” explains Eduardo Rodríguez Farré, researcher at the Barcelona Institute for Biomedical Research (CSIC) and expert in neurotoxicity. ” There is a problem with the leaks, which they have tried to control by freezing the water, but even so, a large part has already been spilled into the sea .”
Indeed, since March 2011 there have already been cases of contaminated water leaks, and last year Tepco, the company that manages Fukushima, admitted that 80% of the water stored in the tanks contains more contaminants in addition to tritium, and some of these Radioactive substances are found in quantities above legal levels.
“Japan has a problem of continuous discharges that will last decades, and in these waters there are radionuclides that have half-lives of many years and that are being incorporated into the trophic chains”, explains the researcher, who cites the case of the tunas of the Pacific Ocean, published in the journal PNAS in 2015, which analyzed the presence of different radioactive isotopes in tuna caught off the coast of California. “We detected levels of cesium 137, which accumulates in the muscles, and strontium 90, which accumulates in the bones , much higher than those they had prior to the accident,” the expert indicates. Regarding the impact on public health, which is yet to be determined, the researcher recalls that “there are already publications in epidemiology journals that point to an increase, as expected, in the incidence of thyroid cancer due to exposure to iodine 131 ”.
Are there other alternatives to the controlled discharge of water?
In an issue as controversial as nuclear energy and the accidents associated with it, which generates heated debates with highly polarized opinions and is subject to political and economic pressure of all kinds, it is difficult to find information and data 100% objectives, both in terms of what the stored water actually contains and its consequences on marine ecosystems.
But what seems clear, and the experts agree on that, is that right now Japan does not have much more room for maneuver when it comes to contaminated water . If indeed the storage capacity has reached its limit, the possibilities are reduced.
Another of the alternatives that is talked about would consist of evaporating the water. “That is possible as long as you have the electrolytic process set up,” Quintana explains. “What you do is evaporate the water at very cold temperatures using magnetic fields, and thus the water with tritium, which is heavier, remains at the bottom and the water without tritium, which is lighter, evaporates. But we return to the issue of scale, I am not an engineer and I do not know if it is feasible to fine-tune this procedure, because we are talking about huge amounts of water. In addition, in the end, the only thing that would be done is to divide the problem, because instead of a single type of effluent, you would have two: one aqueous and the other gaseous “, indicates the expert.
Rodríguez Farré agrees that there do not appear to be other alternatives for the management of radioactive water. “The issue is to know what the consequences of the spill will be. Japan, under enormous pressure in the management of the Fukushima disaster on the occasion of the Olympic Games in 2020, has a very serious problem with this, and it is a problem that will last for years ”, he concludes.
