According to TEPCO, some 1,170,000 cubic meters of water had been treated as of the end of last month by the Advanced Liquid Processing System (ALPS)—multi-nuclide removal equipment—and stored in tanks, with the total tritium content estimated at approximately 856 trillion becquerels (Bq).
Based on that, the power utility performed various calculations on the further assumption that contaminated water would continue to be generated at a rate of 150 cubic meters per day, and that the tritium content would be 860 trillion Bq as of January 1 next year.
The calculations were based on the following hypothetical conditions:
— The quantity of tritium would be reduced by a fixed amount every day through disposal and natural decay.
— Disposal would begin at different times in the future, with calculations for four different starting-point scenarios.
— Disposal would be completed in line with the end of decommissioning, with calculations for two different completion scenarios: after three decades (by December 31, 2041) and four decades (by December 31, 2051).
At a meeting held three months ago, in August, TEPCO presented its plan to secure welded-type tanks of approximately 1,340,000 cubic meters to store water after treatment by ALPS by the end of December 2020. It also presented its calculations showing that those tanks would be full by the summer of 2022 or thereabouts.
For example, the power utility said that if disposal of the treated water were to begin next year, the annual tritium volume would be reduced by some 51 trillion Bq in the scenario in which disposal is completed by the end of 2041, and by some 32 trillion Bq in the scenario where disposal stops by the end of 2051. TEPCO also said that in both cases, given such assumptions, the quantity of water held at any given time would never exceed the tank capacity.
On the other hand, in the scenarios where disposal does not begin next year but rather in 2025, 2030 or 2035, the quantity of water would exceed the tank capacity in the summer of 2022 in all cases. In the 2035 scenario, in particular, the quantity of water would reach approximately 2,000,000 cubic meters by the time disposal began.
An ANRE representative showed the various levels and effects of radiation from the release of water treated by ALPS using an evaluation model of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR).
Regarding offshore release, the calculations considered both external exposure from sand beaches and internal exposure from consumed marine life. Assuming that the treated water stored in tanks was disposed over a one-year period, the radiation effect would be about 0.052 to 0.62 microsieverts (μSvs), markedly less than the annual natural radiation level of 2.1μSvs.
Next, one of the committee members asked about a practical timeline that would take dilution and monitoring into consideration. Another asked about the possibility of reusing the tanks after the water was released. In response to those questions, TEPCO representatives answered that while such actions might be possible, the intention was basically to dismantle the tanks and remove them after releasing the water.
The meeting also discussed the subject of unfounded fears and rumors. In the area of fisheries, Ryota Koyama, professor of food and agricultural sciences at Fukushima University, talked about the Joban mono (“Fukushima marine products) fair currently being conducted at several restaurants primarily in Tokyo and adjacent prefectures.
In the area of tourism, meanwhile, Hiroshi Kainuma, associate professor of the Kinugasa Research Organization at Ritsumeikan University in Kyoto, gave a presentation showing how videos made by overseas influencers could effectively draw the attention of hundreds of thousands of young people.
Both professors emphasized the need to think in new ways, rather than in terms of conventional measures.
