Japan's Nuclear Regulation Authority (NRA) has endorsed Tokyo Electric Power Company's (Tepco's) plan to discharge treated water from the damaged Fukushima Daiichi nuclear power plant into the sea. It will give its official approval of the plan following a 30-day public comment period.

Tanks of treated water at the Fukushima Daiichi site (Image: Tepco)

At the Fukushima Daiichi site, contaminated water - in part used to cool melted nuclear fuel - is treated by the Advanced Liquid Processing System (ALPS), which removes most of the radioactive contamination, with the exception of tritium. This treated water is currently stored in about 1000 tanks on site. The total tank storage capacity amounts to about 1.37 million cubic metres and all the tanks were originally expected to be full around mid-2022. However, last month Tepco said it now expects the tanks to reach full capacity in mid to late-2023.

Japan announced last year it planned to discharge treated water stored at the Fukushima Daiichi plant into the sea over a period of about 30 years, and asked the International Atomic Energy Agency (IAEA) to review its plans against IAEA safety standards which "reflect an international consensus and serve as a global reference for protecting people and the environment from the harmful effects of ionizing radiation".

Tepco submitted its application for the basic design of the ALPS-treated water dilution/discharge facility and related facilities to the NRA on 21 December 2021. Under the plan, the treated water will be diluted with seawater so that the amount of tritium contained will be smaller than one-fortieth of state-set standards. The diluted water will then travel through an undersea tunnel and be discharged about 1 kilometer off the coast.

Tepco said it has "seriously examined the points made by the Nuclear Regulation Authority during review meetings in regards to the implementation plan for the handling of ALPS-treated water, and has reflected these points in revisions of its implementation plan."

The NRA today released its draft report on Tepco's application, giving its consent for the water dilution and discharge plan.

Nearby countries have been alarmed by Japan's plan, but the IAEA has said that the level of tritium in the water will be "well below national regulatory limits and the World Health Organisation standards for drinking water".

"By repeatedly seizing opportunities to carefully explain Tepco's approach to the handling of ALPS-treated water and what we are doing with it, and carefully listening to the opinions, we shall make every effort to eliminate each concern, and get as many people as possible to understand the decommissioning process," Tepco said.

Researched and written by World Nuclear News