Why the contaminated waters of Fukushima will be discharged into the ocean

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Japan has confirmed its intention to gradually discharge tonnes of treated water from the Fukushima Daiichi nuclear power plant into the ocean. Despite fierce opposition from fishermen and other concerns from foreign governments, local authorities believe this is the best disposal option.

The best or the least bad option depends on. Two years ago, we learned that the Fukushima plant will soon no longer have enough space to contain its irradiated water. The local authorities then spoke of “controlled discharge” into the Pacific Ocean of these billion liters of highly radioactive water, presenting it as the most “realistic” option.

The intention was not passed to environmental associations, national fishing crews or even Seoul (Japan and South Korea have always had complicated relations).

Dumping that water into the ocean is the cheapest and fastest option, and we’re confident that’s what it will do. [le Japon]. Once this contaminated water is in the ocean, it will follow ocean currents and end up everywhere. Including in the sea east of Korea“, Then declared Chang Mari, representative of the NGO Greenpeace in the country. “It is estimated that it will take seventeen years for this radioactive contamination to be diluted enough to reach a safe level.“.

The tritium problem in Fukushima

Ten years after this sad event, the clean-up of the site is far from over. To prevent the three damaged reactor cores from melting, cooling water is continuously pumped into them.

This water is then sent through a powerful filtration system capable of removing all radioactive materials (62 radionuclides, atoms that have excess nuclear energy) with the exception of tritium, an isotope of hydrogen with a chemical affinity with water which experts say is not harmful to human health in small doses.

Note that tritium can be carcinogenic and mutagenic in humans, but only in case of exposure to very high doses (of the order of gigabecquerel).

There are now approximately 1.25 million tonnes of wastewater stored in more than a thousand tanks on the plant site. And water continues to accumulate at a rate of about 170 tonnes per day. Tokyo Electric Power Co (or Tepco), which operates the plant, said it would run out of space to build more storage tanks in about two years.

Fukushima Daichi nuclear power plant on February 21, 2007. Credits: Tokyo Electric Power Co., TEPCO

A controlled spill

The Japanese authorities have thus weighed their intentions over the past two years, to finally deliver their verdict on Tuesday: there will be a controlled release of these radioactive waters in the Pacific. The first operations should start in two years and take place over several decades.

The Japanese government has committed to taking “all measures to absolutely guarantee the safety of treated water and fight against disinformation“.

The US State Department hailed the decision: “In this unique and difficult situation, Japan has weighed options and effects, has been transparent and appears to have adopted an approach consistent with global nuclear safety standards.“, Can we read in a press release.

The International Atomic Energy Agency also welcomed the announcement. It will also offer technical support to this mission in accordance with international law. “Today’s decision by the Japanese government is an important step that will help pave the way for continued progress in dismantling the Fukushima Daiichi nuclear power plant“The agency said in a statement.

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