In a review published on 2 April the Vienna-based agency said the two proposals – vapour release and discharges to the sea – were outlined by a Japanese advisory subcommittee in February. They are routinely used by operating nuclear power plants worldwide under specific regulatory authorisations based on safety and environmental impact assessments.
IAEA experts said the subcommittee’s recommendations to the Japanese government were based on a comprehensive and scientifically sound analysis addressing the necessary technical, non-technical and safety aspects. It said a decision on which method will be used should be taken “urgently”.
The government had asked the IAEA to review the management of the stored water. The IAEA and the government have been cooperating extensively over the past decade to deal with the aftermath of the 2011 Fukushima-Daiichi accident, in areas such as radiation monitoring, remediation, waste management and decommissioning.
Reports in Japan have said an average 170 tonnes of contaminated water is being produced each day at Fukushima-Daiichi, mostly as the result of groundwater flowing into the ruined plant.
This contaminated water is treated through a process known as advanced liquid processing system (Alps) to remove radionuclides except tritium and then stored at the site. The total tank storage capacity will amount to approximately 1.37 million cubic metres by the end of 2020 and all the tanks are expected to be full around the summer of 2022.
The IAEA team said water management, including the treated water disposal, was critical to the sustainability of Fukushima-Daiichi decommissioning activities.