Japan on Monday started testing a wastewater discharging facility at the crippled Fukushima Daiichi nuclear power plant that was struck by an earthquake over a decade ago. But it's not the kind of wastewater that flows from city streets into storm drains.

It's the radioactive water used to cool damaged reactors at the plant after the earthquake. For the past 12 years since the accident, the ongoing cooling process has produced over 130 tonnes of contaminated water daily, resulting in a collection of more than 1.3 million tonnes of nuclear wastewater in a tank farm at the plan.

That storage space is about to run out, the Japanese government says, leaving it no choice but to begin dispensing the wastewater into the Pacific.

The plant's operator, the Tokyo Electric Power Company (TEPCO), and the Japanese officials have said the impact of the wastewater discharge "will be minimal," as the water will be treated to legally releasable levels and further diluted with large amounts of seawater, making it harmless to people and marine life.

However, the safety of the treated water remains questionable.

The ALPS 

The wastewater treatment proposed by TEPCO, the Advanced Liquid Processing System (ALPS), is a multi-filter system that can remove radioactive material through a series of chemical reactions. The International Atomic Energy Agency (IAEA) says the system can remove most radionuclides from contaminated water but one – tritium. 

Tritium is a radioactive isotope of hydrogen that is "a relatively weak source of beta radiation" but can be harmful if consumed in large quantities, according to the Canadian Nuclear Safety Commission.

But is the treated wastewater only about tritium, and will the million tonnes of water discharged over decades have no impact on the ecosystem? Experts and scientists around the world seriously doubt it.

Skepticism

First of all, the ALPS filtration system is yet "been shown to be effective all of the time," said Ken Buesseler, a marine radiochemist and adviser to the Pacific Islands Forum.

As reported by the National Geographic, the wastewater stored in the older tanks contains varying levels of radioactive isotopes, such as cesium-137, strontium-90, and tritium, according to Buesseler.

Buesseler said there are other "highly concerning elements … that they haven't been able to clean up," such as cesium and strontium-90, isotopes that have the unpleasant moniker of "bone seeker," as they can increase the chances of developing bone cancer and leukemia.

After analyzing the data from several of TEPCO's wastewater storage tanks, Buesseler and his colleagues said the level of radioactive isotopes in the water varied significantly from tank to tank, even after treatment. "It's unfair to say that they've been successfully removed," he said.

A group of experts associated with the UN also said "the ALPS had failed to completely remove radioactive concentrations in most of the contaminated water stored in tanks at the Fukushima Daiichi plant," a UN press release in April noted. The experts are a group of independent human rights researchers in the UN Human Rights system who report and advise on human rights. 

"A first application ALPS failed to clean the water below regulatory levels, and there are no guarantees that a second treatment will succeed," they said.

A threat to millions

If the hazardous wastewater is discharged, harmful radioactive isotopes also – called radionuclides – could be carried across the entire Pacific Ocean.

In December 2022, the National Association of Marine Laboratories released a statement denouncing Japan's plan to release wastewater. The statement expressed concern about the plan's lack of scientific data supporting Japan's claim of safety, adding that the release may pose a threat to the world's largest body of water and its abundant marine life, including 70 percent of the world's fisheries.   

Robert Richmond, director of the Kewalo Marine Laboratory at the University of Hawaii, also underscored that the radioactive elements in the planned wastewater discharges may once again spread across the ocean. 

Radionuclides may be transported by ocean currents, especially the Kuroshio current that crosses the Pacific, he said. Marine animals that migrate long distances could also contribute to spreading the radionuclides. Phytoplankton, the foundation of the marine food chain, can absorb radionuclides from Fukushima's cooling water.

Even if the wastewater can be treated with only tritium left, UN scientists warn that this isotope organically binds to other molecules, moving up the food chain and affecting plants, fish and humans.

"The radioactive hazards of tritium have been underestimated and could pose risks to humans and the environment for over 100 years," the UN press release said.

Some alternatives

Although it might not be a situation where we are all going to die, "it doesn't mean we shouldn't be concerned," Buesseler said. And there are alternative options.

Kenichi Oshima, a professor at Ryukoku University, put forward two alternatives for dealing with the radioactive wastewater. 

The first is to store the water in large tanks. The half-life of tritium is 12.3 years, so after 123 years of storage, the radioactivity will have decayed to 1/1,000 of its original level. "Japan has experience in oil stockpiling, so this is feasible," said Oshima.

The second is mortar solidification. Mortar solidification can prevent leakage. Mortar solidification has been used in the U.S., Oshima noted.

"We remind Japan of its international obligations to prevent exposure to hazardous substances, to conduct environmental impact assessments of the risks that the discharge of water may have, to prevent transboundary environmental harms and to protect the marine environment," the UN experts said.

The implementation of Japan's discharging plan still needs to await the outcome of the International Atomic Energy Agency's meeting in late June.