TOKYO — Japan’s nuclear regulator on Wednesday approved plans by the operator of the destroyed Fukushima nuclear power plant to discharge the treated radioactive wastewater into the sea next year, saying the methods described are safe and have minimal environmental risks.
The plan was submitted in December by Tokyo Electric Power Company Holdings based on the government’s decision last year to release the wastewater as a necessary step for the ongoing remediation and decommissioning of the plant.
A massive earthquake and tsunami in 2011 destroyed the cooling systems at the Fukushima plant, causing three reactors to collapse and releasing large amounts of radiation. Water used to cool the three damaged reactor cores, which are still highly radioactive, has since leaked but was collected and stored in tanks.
There is still a concern in the community and neighboring countries about the potential health hazards of releasing wastewater containing tritium – a by-product of nuclear power production and possibly carcinogenic in high concentrations.
The government and TEPCO say more than 60 isotopes selected for treatment can be reduced to meet safety standards, except for tritium, but it is safe when diluted. Scientists say the impact of long-term exposure to low doses on the environment and humans is unknown and that tritium may have a greater impact on humans when consumed in fish than in water.
The chairman of the Japanese nuclear authority, Toyoshi Fuketa, said the plan has been made conservative so that the radiation impact on the environment can remain below the legal limit in case of potential risks.
Under the plan, TEPCO will pipeline water treated below-release levels from the tanks to a shoreside facility, where the water will be diluted with seawater.
From there, TEPCO said that the water enters a submarine tunnel to be discharged at a point about 1 kilometer (0.6 mi) from the plant to ensure safety and minimize the impact on local fisheries and the environment.
The plan will become official after a 30-day public review, a formality that is not expected to overturn the approval.
The green light came as Mariano Grossi, director of the International Atomic Energy Agency, arrived in Japan to meet with top officials to discuss the plan, which has attracted international attention.
Fuketa will meet with Grossi on Friday following the IAEA director’s visit to the Fukushima plant and meetings with other Japanese officials.
The government and TEPCO plan to begin phasing out the treated water in the spring of 2023.
The contaminated water will be stored in about 1,000 tanks at the damaged factory, which officials say will need to be removed to build facilities for decommissioning. The tanks are expected to reach their capacity of 1.37 million tons next year, slower than an earlier estimate released later this year.
Japan has enlisted the help of the IAEA to ensure its waters meet international safety standards and to reassure local fishermen and other communities, as well as neighboring countries that have strongly criticized the plan.
A team of IAEA experts visited the plant in February and March to meet with the Japanese government and TEPCO officials. The task force said in a report released in late April that Japan is making “significant progress” with the plan and is taking appropriate steps toward the planned discharge.