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 more than 1000 tanks on site. The total tank storage capacity amounts to about 1.37 million cubic metres and all the tanks are expected to reach full capacity in late 2023 or early 2024.
Japan announced in April 2021 it planned to discharge treated water stored at the site into the sea over a period of about 30 years.
At the meeting today of the Inter-Ministerial Council, the government announced that it had made a decision regarding the start of the discharge of ALPS treated water into the sea.
Prime Minister Fumio Kishida, speaking at a press conference following the meeting, said: “A task that cannot be postponed in order to restore the livelihood of Fukushima and achieve reconstruction is the steady decommissioning of the damaged reactors at the Fukushima Daiichi nuclear power plant.” However, he noted the storage of the accumulated water has taken up much of the available space on the site. “We are running out of room to create the necessary space to further steadily advance the decommissioning process of Fukushima Daiichi. In order to overcome this situation, we cannot avoid the disposal of ALPS-treated water, which is a prerequisite for decommissioning.”
Tepco said it will “quickly make preparations to commence discharge with the utmost vigilance in accordance with the implementation plan”.
The company said that during the initial stages of the discharge, a very small amount will be released using a two-step process. In the first step, which has now begun, a very small amount of ALPS treated water will be diluted with seawater and stored in the vertical discharge shaft (upstream water tank) in order to verify that ALPS treated water is being diluted as planned. After this stored water has been sampled and tritium concentrations measured, it will move on to the second stage, the continuous discharge into the sea, on and after 24 August.
