Japan's Nuclear Regulation Authority (NRA) has endorsed a plan to discharge into the sea treated water stored at the damaged Fukushima Daiichi NPP. The plan, which is expected to start in 2023, will be officially approved in July at the earliest after NRA hears submissions from the public, according to NRA Chairman Toyoshi Fuketa.
Japan's Economy, Trade and Industry Minister, Koichi Hagiuda, thanked visiting International Atomic Energy Agency (IAEA) Director General Rafael Grossi for his leadership in leading the IAEA's review on the planned water discharge, saying the release of a report last month was "a major step forward" toward executing the plan in a safe manner.
In late April, the IAEA task force released its first evaluation report on the technical preparations for the discharge, saying the plan is so far making good progress but needed further improvement.
Grossi was quoted by the ministry, in a written statement, as saying that the IAEA review will assure people around the world that water, treated through an advanced liquid processing system that removes radionuclides except for tritium, will not have a harmful impact on public health and the environment.
More than 1 million tons of treated water has accumulated at the Fukushima NPP since the March 2011 earthquake and tsunami triggered the meltdown of three reactor cores. Water pumped into the ruined reactors at the Fukushima plant to cool the melted fuel, mixed with rain and groundwater, which has also been contaminated, is being treated using an advanced liquid processing system (ALPS). The process removes 62 radionuclides, including strontium and caesium, as well as Carbon-14, but leaves behind tritium. The decision to release the water offshore into the Pacific is aimed at preventing reputational damage to local marine products amid an outcry from fishermen.
The treated water is currently stored on the Fukushima Daiichi site in more than 1000 large tanks with a storage capacity of about 1.37 million cubic metres. However, the complex is expected to run out of water storage capacity by the summer of 2022, with contaminated water increasing by about 170 tons a day.
Plant operator, Tokyo Electric Power Company Holdings (Tepco) will need to gain consent from municipalities hosting the power complex to start construction of the water discharge facilities. The treated water will be diluted with seawater to one-40th of the concentration permitted under Japanese safety standards and released one kilometre off the power plant through an underwater pipeline, according to the plan.
Tepco applied for an evaluation of the plan by the NRA in December. Through a total of 13 review meetings, the watchdog evaluated the function of the diluting facility, as well as a method of suspending the discharge of treated water when an unusual situation is detected, and measures against earthquakes and tsunami, among others.
The NRA concluded the water discharge will help the operator secure space for facilities needed for future decommissioning work and lower overall risks to the Fukushima plant. Fuketa also asked Tepco to ensure there are no incidents at the planned water discharge facilities, given that the treated water has to travel quite a distance before discharge.
The NRA plans to make a decision on final approval after a one-month public comment period, an official at NRA said. Yoshihiro Murai, the governor of Miyagi Prefecture adjacent to Fukushima Prefecture, said he will continue to urge Tepco and the central government to explore alternatives to releasing treated water into the sea.
Image: Some of the large tanks currently used to store treated water at the Fukushima Daiichi site