Discussions on Tritiated Water Treatment for Fukushima Daiichi Nuclear Power Station

A series of discussions on tritiated water of the Fukushima Daiichi Nuclear Power Station (FD-NPS) was carried out. A large amount of contaminated water has been generated in FD-NPS. Radioisotopes in the contaminated water have been removed except tritium, and thus, tritiated water has been left and stored. As of March 2019, 1 126 500 m3 of tritiated water has been stored in tanks. The average tritium concentration in the tritiated water is 1000 Bq/cm3.Various options for handling the tritiated water, such as discharge into the sea, geosphere injection, underground burial, and vapor or hydrogen release with and without pretreatment, were discussed on the basis that there is no scientific impact on people. Through the discussions, 11 options for handling tritiated water were summarized. At the same time, some experimental tests of tritium separation (with small-scale and/or full-scale component test stands) were also carried out. As a result, it was concluded that the tested separation technologies could not yet be applied to the case of FD-NPS. No selection from the 11 options has yet been recommended, and further discussions for the tritiated water have continued with public hearings.