The plan announced by Japanese authorities to release radioactive water from the Fukushima nuclear power plant into the ocean has been causing controversy among neighboring countries and environmental NGOs. The waste — which has already been treated — takes up more than a thousand tanks and needs to be disposed of so that the remediation works can continue at the site.
It may sound like a bad idea, as it did for China, South Korea and several Pacific islands, but the government of Japan, the International Atomic Energy Agency (IAEA) and scientists unrelated to the plan have declared it to be safe. Recently, an article published by Australian experts on the portal The Conversation reinforces this position.
With long professional and academic experience in the field of nuclear science and energy, scientists assess the type and amount of radiation to be released, as well as the radiation already present in the ocean. The analysis concludes that there are no risks and the measure is necessary for Japan to continue with the recovery process in the area.
What’s in Fukushima’s water
A total of 1.3 million tons of water — enough to fill 500 pools the size of which athlete Bruno Fratus swam to win a bronze medal at the Tokyo Olympics. This is the amount stored so far in Fukushima. It was used in the continuous cooling process of the plant’s reactors.
In addition, a large volume of water is contaminated every day in the soil below the site. The facility in which the reactors operated was built at the level of the water table precisely to use the liquid for cooling. It is necessary to proceed with the process of remediation of the area so that the 140,000 liters contaminated daily are zeroed.
All of this water—both what was used while the plant was active and what is contaminated on a daily basis—is treated through a process called Advanced Liquid Processing System (ALPS). The treatment can be repeated as many times as necessary to bring the water within legal standards, a monitoring that is carried out by the IAEA.
The only radioactive contaminant that ALPS cannot remove is tritium—a form of hydrogen that has two neutrons and one proton in its atomic nucleus. As with every radioactive element, tritium’s radiation decreases over time at a rate called its half-life. The term refers to the period required for the radiation to drop by half.
In the case of tritium, there are 12 years of half-life, or a century until it is practically zero, a time that is too long to maintain storage in the tanks.
Why is it safe to release tritium?
There are national and international standards regarding water potability, placing limits on the presence of a series of substances after treatment processes. In Brazil, the Ministry of Health requires that the concentration of uranium in water does not exceed 0.03 mg per liter.
In the case of tritium, the international standard is measured in a unit called Becquerel (Bq), which indicates the radioactive decay in the sample. The World Health Organization (WHO) establishes 10,000 Bq per liter as a parameter for drinking water, while Japan intends to release water from Fukushima into the ocean with only 1,500 Bq per liter.
In addition, small amounts of radiation are present at all times in our daily lives: even the air, plants and even our food emit radiation to some extent, in insignificant amounts for health. The Pacific Ocean itself already contains about 3 quintillion — 3 billion billion — Becquerels of tritium.
The number is so large that it is possible to express it in the total mass of the element: it would be 8.4 kg of tritium in the entire volume of the largest ocean in the world. By comparison, Japan aims to release a total of around 3 grams with Fukushima water, at a rate of 0.06 grams per year (22 billion or 22 TBq).
Finally, other nuclear power plants are also required to dispose of the substance in some way. China and Korea release more than 50 TBq per year from their respective Kori and Fuqing plants. In the UK, the Heysham plant can reach 1,300 TBq per year and has been in operation for 40 years.
There is justifiable resentment in the Pacific Islands towards nuclear technologies due to the legacy of bomb tests carried out in the region. Either way, the difference Fukushima waters would make would be minimal. Twelve years after the earthquake that left almost 20,000 dead, the region must continue its reconstruction process.
Source: The Conversation
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