5.5m3 of contaminated water leaked into the environment before being treated on Wednesday. The leak was stopped about twenty minutes after its discovery Wednesday morning by a worker who was cleaning exhaust pipes on the site.
This water could contain radioactive isotopes such as cesium 137 and strontium 90. The Fukushima Daiichi nuclear power plant was devastated by the 2011 tsunami in northeastern Japan. Decontamination and dismantling of the plant are still decades away, with the most difficult part - extracting the melted fuel from its damaged reactors - yet to begin.