Photo: Dead abalone in tritium-contaminated water in Tepco’s experimental environment. The brown crack is evident on its shell. (From Tepco’s twitter)
Since October of 2022, Tepco has been implementing the breeding experiment of marine life in normal seawater and the water contaminated with tritium, which is planned to be discharged to the Pacific. Currently, flounder and abalone are monitored.
According to Tepco’s record, 2.6 times more abalone died in the tank with the tritium water.
From the 3rd of October, 2022 to the 20th of January, 2023, 29 abalones have been reportedly confirmed to be dead in the contaminated seawater, which include 1,500 Bq/L of tritium. On the contrary, as few as 11 abalones died in the same period of time in the normal seawater.
Tepco announced the significant difference of abalones’ survival rates is due to the density in each tank. At the moment of the 14th of December, 2022, 308 abalones were living in the tank with the normal seawater, while 384 abalones were living in the tank with tritium-contaminated water. However, the sizes of the tanks are not disclosed. Also, it is unclear why Tepco did not set every tank in the same conditions as the control group and treatment group.
Approximately 1,150 Bq/L of tritium was detected from abalone by the time when 24 hours had passed since it was moved into the tritium-contaminated water. The tritium density in abalone slowly increased up to 144 hours after the relocation, nevertheless Tepco interrupted the tritium density measurement to conclude the biological concentration wasn’t observed.