A top government spokesperson recently announced that Japan is taking steps toward discharging more than a million tonnes of treated radioactive water from the damaged Fukushima nuclear power plant into the ocean this year.
The International Atomic Energy Agency (IAEA) has approved the proposal, and the government will use every effort to guarantee security and implement safety measures.
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Treated radioactive water set to be released into the Pacific Ocean
Between April and November of last year, the site generated 100 cubic meters of polluted water per day on average, which included groundwater, ocean, precipitation that seeped into the area, and water used for cooling.
Since more than 1.3 million cubic meters of water are on site and the room is running out, the water is filtered to eliminate different radionuclides and transferred to storage tanks.
Safety measures promised
The water is put through a complicated series of filters by Tokyo Electric Power Co. (TEPCO), which it refers to as the Advanced Liquid Processing System (ALPS). As a result, tritium, a radioactive hydrogen isotope with a 12.3-year half-life that exists naturally in microscopic levels in seawater and the atmosphere, is not captured by the treatment, which only removes 62 different radionuclides.
Removal is particularly challenging as it takes the place of hydrogen atoms in water molecules. Tritium is a negligible danger to health since it only emits low-energy beta particles. The tritium content in the water will be diluted to a level that is one-fourth of what Japan permits in drinking water.
Diluting radioactive levels to ‘acceptable levels’
According to Nigel Marks, a nuclear materials specialist at Curtin University, releasing the water into the Pacific Ocean is the right thing to do even though “the aesthetics are dreadful.”
According to Marks, diluting can lower radioactivity to acceptable levels equivalent to exposures from medical imaging and plane travel. But in addition to tritium, the ALPS procedure can occasionally allow for the passage of more unstable isotopes with longer radioactive lives, such as ruthenium, cobalt, strontium, and plutonium. TEPCO finally confirmed this in 2018. These extra nuclides are currently found in 71 percent of the tanks.
The potential risk of radioactive isotopes
According to Ken Buesseler, a marine scientist at the Woods Hole Oceanographic Institution, “These radioactive isotopes behave differently than tritium in the water and are more readily integrated into marine biota or bottom sediments.”
According to the government official, the water from Fukushima will be “repurified” to comply with legal requirements for these nuclides. Buesseler points out that such restrictions weren’t made for the intentional discharge of contaminated water from a nuclear accident, but rather for atomic power reactors still in operation.
Environmental groups propose alternative solutions
Shigeyoshi Otosaka, a marine geochemist at the University of Tokyo, is concerned about the concentration of the isotopes in sediments on the bottom since marine biota may consume them there. He adds that the likelihood is slim, but it’s crucial to assess it correctly.
For starters, the TEPCO “repurification” has only been tried on a tiny amount of water. According to him, the business must confirm “if the processing performance can be maintained for a lengthy period.”
Environmental groups assert that there is the capacity for more tanks on land next to the Fukushima site, despite TEPCO’s claim that it will run out of space to store more water by the middle of 2022. This would buy time for the radioactive isotopes to decay while also enabling their storage of them naturally.
After the release, facilities have been finished and tested, and the IAEA’s entire report has been made public, Japan estimates the release timeframe would be around this spring or summer.
Radioactive debris washed into the Pacific Ocean after the earthquake and tsunami that followed the Fukushima nuclear disaster have led to fears of further radiation releases. An estimated 538.1 petabecquerels of radioactivity — around a sixth of the Chornobyl dose — have been released into the atmosphere.