The third round of discharging treated radioactive water from the wrecked Fukushima No. 1 nuclear power plant into the sea concluded Monday, the plant operator said, with the utility planning another round in the current fiscal year.
As in the previous rounds, Tokyo Electric Power Company Holdings (Tepco) released about 7,800 metric tons of processed water about 1 kilometer off the coast via an underwater tunnel from Nov. 2.
China and Russia have maintained restrictions on marine product imports from Japan since the start of the discharge in August.
In four rounds of discharge, to be completed in the current fiscal year through March, Tepco plans to release about 31,200 metric tons of water treated through an advanced liquid processing system that removes most of the radioactive substances except tritium.
The total amount of tritium released into the sea is expected to be around 5 trillion becquerels, less than a quarter of the annual limit of 22 trillion becquerels.
Tepco aims to dispose of 1.34 million metric tons of water collected in over 1,000 tanks at the power plant over the next three decades after diluting it with seawater to one-fortieth of the tritium concentration level permitted under Japanese safety standards.
Since the beginning of the discharge, Tepco said it has detected up to 22 becquerels of tritium per 1 liter of seawater in samples taken from areas near the outlet, far below the World Health Organization's limit of 10,000 becquerels for drinking water.