Initially, Japan planned to discharge water purified from all radionuclides except for tritium into the ocean 1 kilometer (0.6 mile) off the station starting this spring. However, the deadline was postponed to the summer of 2023 due to unfavorable weather conditions and other delays.
The system is almost complete, as the tunnel for the discharge of water was finished in April, the NHK broadcaster reported on Monday. The only thing left to build is a reservoir for treated water.
TEPCO employees started filling the tunnel with sea water on Monday, according to the report. By Tuesday afternoon, it will be filled with 6,000 tonnes of sea water in order to mix it then with low-level radioactive water for the subsequent release.
In January, the International Atomic Energy Agency (IAEA) completed an inspection of Japan's Fukushima nuclear power plant as part of an assessment of the Japanese operator's plan for wastewater discharge.
The nuclear disaster at the Fukushima NPP occurred on March 11, 2011. The plant was heavily damaged following a magnitude 9 earthquake in the Pacific Ocean. This triggered a massive tsunami that hit the plant and caused three nuclear reactors to melt down. The accident is regarded as the worst nuclear disaster since the 1986 Chernobyl accident, resulting in the large-scale contamination of local soil and water. The disaster resulted in 22,200 people dead or missing.