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CNN goes inside the Fukushima nuclear plant where wastewater is being treated
03:36 - Source: CNN
Tokyo CNN  — 

After months of controversy and anticipation, Japan is set to begin releasing treated radioactive wastewater from its Fukushima nuclear plant later this week despite fierce objections from some countries.

The plan has been in the works for years, with authorities warning in 2019 that space was running out to store the material and they had “no other options” but to release it.

While some governments have expressed support for Japan, others have strongly opposed the wastewater release, with many consumers in Asia hoarding salt and seafood amid fears of future contamination.

Here’s what we know so far.

When and how will it be released?

Japanese Prime Minister Fumio Kishida said Tuesday the government had formally decided to start releasing the water as early as Thursday, August 24, “if they encounter no obstacles.”

Over the years, the wastewater has been continually treated to filter out all the removable harmful elements, then stored in tanks. Much of the water is treated a second time, according to the state-owned electricity firm Tokyo Electric Power Company (TEPCO).

When the wastewater is finally released, it will be be heavily diluted with clean water so it only has very low concentrations of radioactive material. It will travel through an undersea tunnel about 1 kilometer (0.62 miles) off the coast, into the Pacific Ocean.

Third parties will monitor the discharge during and after its release – including the United Nations’ nuclear watchdog, the International Atomic Energy Agency (IAEA). The IAEA has staff stationed in a newly-opened Fukushima office and will monitor the situation for years to come, it said.

A TEPCO researcher assesses the radiation impact of treated wastewater in  Fukushima, Japan, on April 12, 2023.

Why are they doing this?

The devastating 2011 earthquake and tsunami damaged the Fukushima nuclear plant’s power supply and cooling systems – causing the reactor cores to overheat and contaminate water within the plant with highly radioactive material.

Since then, new water has been pumped in to cool fuel debris in the reactors. At the same time, ground and rainwater have leaked in, creating more radioactive wastewater that now needs to be stored and treated.

TEPCO built massive tanks to contain the wastewater, but space is quickly dwindling. The company says building more tanks isn’t an option, and it needs to free up space to safely decommission the plant.

IAEA Director General Rafael Grossi told CNN in July that Japan had considered five options for getting rid of the water, including vapor release, which would have seen wastewater boiled and released into the atmosphere.

But most of these options are “considered industrially immature,” he said. For instance, vapor release can be more difficult to control due to environmental factors like wind and rain, which could bring the waste back to Earth, he said. That left a controlled release of water into the sea – which is frequently done at nuclear plants around the world, including those in the United States.