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Japan to Release 1.3 Million Tonnes of Water Used During Fukushima Nuclear Accident

The water used to cool damaged reactor cores from the Fukushima Daiichi Nuclear Power Plant accident in March 2011.

David Krofcheck, The Wire 16 Jul 23

“…………………………………………This year the Japanese government plans to release 1.3 million tonnes of water – used to cool the damaged reactor cores from the Fukushima Daiichi Nuclear Power Plant accident in March 2011 – into the Pacific Ocean

Between 2011-2013, approximately 300,000 tonnes of untreated wastewater had already flowed into the ocean off Fukushima. These first two years were the most dangerous time because long-lived heavy nuclei, like cesium-137, strontium-90 and shorter-lived iodine-131, from nuclear fission in the reactors ended up in the ocean.

Since 2013, the stored water has also accumulated flushed seawater goundwater which leaked into the three damaged reactor cores.

The big challenge is how to manage 1.3 million tonnes of unsafe radioactively-tainted water………………………………………………………………………….

“As Low As Reasonably Achievable” or ALARA – filtering out the nuclear fission nuclei from the stored wastewater may be the best that can be done. The ALARA approach to reduce nuclear fission nuclei released resulted in a 2013 effort to develop and employ an advanced liquid processing system, or ALPS. A series of filters was designed to remove 62 fission nuclei leaving both tritium and carbon-14 in the water.  It only partially worked.

 Potentially, this water could be run through more cycles of the ALPS before extra dilution and later release into the ocean.

The other 30% of treated water could also be diluted with seawater by factors of several hundred to one thousand and then released into the ocean. Any remaining tritium from the Fukushima reactor may find its way into the food chain as organically bound tritium via build-up in underwater plants and organisms.

The second option for managing the Fukushima water was to hold it on site in an ever-increasing number of tanks.

If the water is properly filtered to leave only tritium and carbon-14, then the natural decay of tritium can be used to reduce overall radioactivity.  Since the radioactive half-life of tritium is 12.4 years, holding the water in tanks for seven half-lives, about 85 years, would reduce the tritium content to less than 1% of its current value. This option leaves the carbon-14 which would still roughly have the same radioactivity due to its 5,730-year half-life.

However, storing a tremendous volume of water for an entire human lifespan has never been tried. Even more water and storage tanks would need to be added as decommissioning the Fukushima Daiichi nuclear reactor cores proceeds. This is problematic.

A third option was to evaporate the water on land near Fukushima.

A 1979 nuclear accident at Three Mile Island Nuclear Station in the United States resulted in a similar radioactive water storage problem. About 9,300 tonnes of tritiated water, about 140 times less than that currently held in the Fukushima storage tanks, was electrically evaporated over two years. The tritium was released into the atmosphere, resulting in a radiation dose to people in the surrounding area of about one-hundredth of the natural background radiation. 

Japan and TEPCO would need to deal with even larger amounts of water and tritium emitted into the atmosphere if the 30-year timeline for the reactor core clean-up is followed……………….. https://thewire.in/environment/japan-to-release-1-3-million-tonnes-of-water-used-during-fukushima-nuclear-accident

July 18, 2023 - Posted by Christina Macpherson | Fukushima continuing, oceans, Reference