Tokyo Electric Power Company Holdings (Tepco) has begun the 19th discharge to the sea of treated water from the crippled Fukushima Daiichi NPP since the operation began in August 2023. The discharge, set to run until 20 April will comprise about 7,800 tonnes of Advanced Liquid Processing System (ALPS) treated water. So far, approximately 141,000 tonnes of wastewater have been released into the sea.
Contaminated water, used to cool the melted reactor cores in the aftermath of the 2011 nuclear disaster at Fukushima, is stored in around 1,000 huge tanks at the plant site containing more than 1.3m tonnes and total storage capacity has been reached. The contaminated cooling water and groundwater is treated by ALPS, which removes most of the radioactive contamination, with the exception of tritium. The treated water is then stored in tanks before being diluted with seawater to one-fortieth of the concentration permitted under Japanese safety standards prior to being released through pipeline one kilometre offshore.
According to the International Atomic Energy Agency (IAEA), the tritium concentration of the 19th batch of treated water is far below Japan’s operational limit and consistent with international safety standards.
As part of its ongoing safety assessment, the IAEA conducted independent sampling of the latest batch prior to its release via a one‑kilometre tunnel into the ocean. On‑site analysis confirmed that the tritium concentration is far below Japan’s operational limit of 1,500 becquerels per litre and in line with international safety standards.
