In satellite pictures, they look like the pale blue and gray eggs of a giant butterfly, laid in tight patterns on some dismal leaf. The eggs, made of steel, are tanks brimming with radioactive fluid—contaminated water from Japan’s Fukushima nuclear plant. The water will soon be diluted and pumped into the sea. Núria Casacuberta Arola, of ETH Zürich, is among those who will be watching. Closely.
“We have access to a ship that goes to the coast of Fukushima every year, sometimes once, sometimes twice,” she says. Casacuberta Arola and her colleagues regularly drop an assembly of jars into waters near the incapacitated power plant to collect samples at different depths. The lids of the jars close automatically, one by one, as the device is slowly pulled back up to the surface.
By doing this, and also taking sediment samples from the seabed, they hope to be able to tell in the coming months and years whether the disposal of water from Fukushima is causing a noticeable rise in radiation in this corner of the Pacific Ocean. The water release could start as early as next month. If there is a significant bump in radiation levels in the surrounding waters, it will mean things have gone very wrong.
In 2011, a massive tsunami struck Fukushima Daiichi Nuclear Power Station. The defensive sea wall intended to protect the plant from such an onslaught was many meters too low to stop the monster wave. Seawater flooded the facility, ultimately leading to partial meltdowns and huge explosions at some of the reactors. It is considered one of the worst nuclear accidents in history.
In the years since, workers have had to constantly pump water into Fukushima’s stricken reactors, which still contain hot nuclear fuel. This water has, thankfully, done its job of keeping the reactors cool, but it has become irradiated in the process, meaning it can’t just be flushed away. Workers have kept the used cooling water on-site, building tank after tank in which to store it. All the while, they have known that they will eventually have to dispose of it. Today, there are 1.3 million metric tons of contaminated water on-site. And no space for any more tanks. The time to do something about it is here.
It has taken years of research, modeling, and sampling, but earlier this month the International Atomic Energy Agency gave its approval for a discharge plan. Japan’s Nuclear Regulation Authority signed off on the proposals at the same time, meaning that the Tokyo Electric Power Co (Tepco), which is in charge of the plant and its cleanup, has full authority to begin slowly releasing the water into the ocean via a 1-km-long underwater pipe.
Some aren’t happy. Local fishers are strongly opposed to the plan, and there have been street protests in South Korea. Yet many scientists are highly confident that the discharge will be perfectly safe.
The contaminated water, enough to fill more than 30,000 fuel-truck semi-trailers, contains a mix of unstable chemical elements, known as radionuclides, that emit radiation. To keep these radioactive components to a minimum, Tepco has installed special water purification technology that treats the water before storage. In essence, it involves passing the contaminated water through a series of chambers containing materials that can adsorb radionuclides. The isotopes stick to those materials and the water flows on, a little cleaner than before.