We unpacked Japan's plan to release Fukushima wastewater

Japan began releasing wastewater from the crippled Fukushima nuclear plant into the Pacific Ocean on August 24, as tanks containing the radioactive water neared capacity. STR/JIJI Press/AFP via Getty Images hide caption

toggle caption STR/JIJI Press/AFP via Getty Images

Japan began releasing wastewater from the crippled Fukushima nuclear plant into the Pacific Ocean on August 24, as tanks containing the radioactive water neared capacity.

STR/JIJI Press/AFP via Getty Images

Workers in Japan started releasing treated radioactive water from the Fukushima Daiichi nuclear power plant into the Pacific Ocean on Thursday.

In 2011, an earthquake and tsunami hit the Fukushima area and triggered reactor meltdowns at the plant.

For today's show, host talks to NPR reporters and about all things Daiichi, the plan to release the radioactive water and why some are unhappy about it.

They begin with what the meltdown of a nuclear reactor means. (Spoiler alert: It's just as bad as it sounds.) "Basically what it means is the nuclear fuel inside the reactor gets so hot, it starts to melt and clump together," senior science correspondent Geoff Brumfiel says. "And that can lead to a runaway chain reaction."

To stop the meltdown, plant workers flooded the reactors with water. But even now, when the plant is offline, the reactors need to be cooled. All that water—about 350 million gallons—is being stored on-site in over 1,000 tanks.

And now, Japan has begun pumping the treated water into the Pacific Ocean.

What's in the water?

Under normal circumstances, nuclear reactors are controlled environments. But after a reactor meltdown, dangerous radioactive isotopes like cesium-137 and strontium-90 contaminate the water.

"Part of what makes this tricky is this is a very uncontrolled environment," Geoff says. "We have a lot of nuclear material and water mixing together."

These isotopes are known to make people and animals sick—and can even cause cancer over time. So, the Japanese government has created a system called the Advanced Liquid Processing System (or ALPS, for short) to filter out several of these radioactive isotopes from the water.

But there's one isotope they cannot get rid of: tritium. Tritium is an isotope of hydrogen. Since hydrogen is part of water itself, there's no filter to remove it. Tritium is less dangerous than other isotopes and occurs naturally in the environment.

The government plans to dilute the water so there's less tritium in every drop. The water will also go through long underground tunnels before entering the Pacific Ocean, which will dilute it further.

, a professor of environmental science at the University of Portsmouth. "I would call it not a risk at all. We've got to put radiation in perspective, and the plant release—if it's done properly—then, the doses that people get and the doses that the ecosystem get just won't be significant, in my opinion."

However, some people still worried about long-term risks of the plan, both to people and to the environment.

"We're not going to suffer directly from the doses from this. But it's, you know, one of the many things we're adding to our ocean that if you have an alternative, we certainly should consider more fully," says , a senior scientist at the Woods Hole Oceanographic Institution. "And I don't think that's been done in the past couple of years."

How are people reacting?

Reactions to the release have been mixed. Local fisheries worry about contaminants that may remain in the water after filtration, and about business following the release.

These concerns spread beyond Japan as well. China banned seafood imports from the area, and there have been protests in South Korea.

After the 2011 disaster, Kat reports that Tokyo Electric Power Company (TEPCO)—the company that ran the plant—and the Japanese government were not transparent about data and information surrounding the meltdown.

"That skepticism isn't coming from nowhere," Kat says. "They were not transparent. And they've since apologized and are trying to be more transparent. But there's this deep distrust that's still there."

This skepticism exists in many Pacific Island nations, too, after decades of grappling with the consequences of nuclear testing in the region by other countries.