Fukushima Nuclear Plant, Japan is to issue its gravest warning about the state of the wrecked Fukushima Daiichi nuclear power plant since the facility suffered a triple meltdown almost two and a half years ago.
The new warning, expected on Wednesday, comes only a day after the nuclear watchdog assigned a much lower ranking when the plant’s operator, Tepco, admitted about 300 tonnes of highly toxic water had leaked from a storage tank at the site.
The Nuclear Regulation Authority has now said it will dramatically raise the incident’s severity level from one to three on the eight-point scale used by the International Atomic Energy Agency (IAEA) for radiation releases. Each single-digit increase in the scale actually represents a tenfold increase in the severity of a radiological release, according to the IAEA.
The NRA on Tuesday classified the leakage only as an “anomaly” on the IAEA scale but now considers it a “serious incident”.
The leak is the single most dangerous failure at the plant since the 2011 meltdown, which warranted the maximum level of seven on the severity scale, putting it on a par with the Chernobyl disaster 25 years earlier.
“Judging from the amount and the density of the radiation in the contaminated water that leaked … a level three assessment is appropriate”, the NRA said in a document posted on its website on Wednesday.
Tepco has admitted it has yet to identify the cause of the leak, in which highly radioactive water appears to have breached a steel storage tank and seeped into the ground. The leak from the tank, which can hold up to 1,000 tonnes of water, has yet to be stemmed, according to Japanese media reports.
The incident is separate from additional water leaks of up to 300 tonnes a day recently reported by Tepco.
Those spillages involve groundwater that is leaking into the nearby Pacific ocean. Tepco said there was no evidence that water from the storage tank had found its way into the sea. The utility said radioactive matter, including caesium and strontium, had seeped into soil, which may have to be dug up and removed.