Science

Despite opposition, Japan may soon dump Fukushima wastewater into the Pacific

TOKYO—The Japanese government is pushing ahead with its plan to release 1.3 million tons of radioactive water from the defunct Fukushima Daiichi Nuclear Power Plant into the Pacific Ocean. The release could begin as early as this spring or summer, according to materials distributed at a 13 January ministerial meeting. But it has stirred broad opposition—from Japan’s fishing industry and consumers, countries throughout the Asia-Pacific region, and some marine scientists.

The Tokyo Electric Power Company (TEPCO), which owns the power station, says it is running out of space to store the water on land. Radioactivity levels in the discharged water will be too low to pose a risk to marine life or humans, TEPCO says, and its plan has the blessing of the International Atomic Energy Agency (IAEA). At a 20 January briefing here, IAEA nuclear safety official Gustavo Caruso, who heads a special agency task force on Fukushima, said Japan’s Nuclear Regulation Authority (NRA) has procedures in place to ensure the discharge meets international safety standards.

But critics say the risks haven’t been studied in enough detail. TEPCO’s assurances are “not supported by the quantity and quality of the data,” says oceanographer Ken Buesseler of the Woods Hole Oceanographic Institution. “We need more information.” The release would set an awful precedent, says Robert Richmond, a marine biologist at the University of Hawaii, Manoa: “There is a strong consensus internationally that continued use of the ocean for dumping waste is simply not sustainable.”

Ever since the 2011 Tohoku earthquake and tsunami devastated the Fukushima power plant, crews have continuously pumped water through the wrecked reactors to cool the nuclear fuel, much of which melted. The cooling water picks up radio-
nuclides, many of which are then captured by a specially developed filtering process. But tritium, which is chemically identical to the ordinary hydrogen in water, slips through the system. For now, the water is stored in more than 1000 tanks on the plant grounds.

Tritium gives off only low-energy beta particles believed to pose minimal risks for marine life and humans. And TEPCO plans to dilute the waste with massive amounts of seawater to reduce tritium levels below regulatory standards for drinking water before dumping it into the ocean through a pipe extending 1 kilometer offshore.

A level safe for drinking sounds reassuring, but is still thousands of times higher than the natural level in seawater, Richmond says. And the water will be discharged at a single point for decades, so tritium, which can be bound into animal and plant tissue, and other radioactive isotopes may still accumulate in marine organisms and work their way up the food chain to fish and humans. “This has real implications for ocean life and the human lives that are tied to our oceans now and into the future,” Richmond says.

Other radionuclides may also be slipping through, says Ferenc Dalnoki-Veress, an expert in low concentration radioactivity measurements at the Middlebury Institute of International Studies at Monterey. “What’s in the water? We don’t really know,” he says. TEPCO has sampled small amounts of water from just one-quarter of the tanks, he says, and measured concentrations of tritium and only a limited number of other radionuclides. Strontium-9 and cesium-137, radioactive products of nuclear fission, have turned up in wildly varying concentrations, raising questions about how well the filtration system works. (TEPCO maintains that further filtering will capture more of the radionuclides.)

Japan’s neighbors share the concerns. “There should be no discharge until all parties verify through scientific means that [it] is safe,” Henry Puna, secretary general of the Pacific Islands Forum, a group of 16 countries, said at a recent seminar. The U.S. National Association of Marine Laboratories also opposes the plans, citing “a lack of adequate and accurate scientific data supporting Japan’s assertion of safety.”

Scientists have put forward alternatives. Richmond sees an opportunity for bioremediation, by pumping the wastewater through tanks full of oyster species that consume plankton and incorporate radionuclides into their shells. If other radionuclides are removed, the contaminated water could simply be stored for 40 to 60 years, since tritium has a half-life of only about 12 years. Or the water could be used to make concrete, from which tritium’s beta particles are unable to escape.

But TEPCO is pressing ahead. NRA will monitor the entire operation, as will IAEA and at least one third party commissioned by TEPCO. Independent groups will also be watching. A group led by Núria Casacuberta Arola, an oceanographer at ETH Zürich, collected samples off the coast of Fukushima in November 2022 that will provide baseline concentrations of tritium and other radionuclides, with which any changes can be compared. But more studies should be done before the releases begin, Richmond says: “Monitoring does not prevent problems from occurring, it identifies when problems occur.”

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