Tokyo - Radioactive groundwater at the crippled Fukushima nuclear plant has risen to levels above a barrier being built to contain it, highlighting the risk of an increasing amount of contaminated water reaching the sea, Japanese media report.
The Asahi newspaper, citing data from a meeting of a task force working on the Fukushima clean-up at Japan's nuclear regulator, estimated that the contaminated water could swell to the ground surface within three weeks.
The latest revelation underscores the hurdles facing Tokyo Electric Power (TEPCO) 2-1/2 years after a massive earthquake and tsunami destroyed the Fukushima plant, triggering the world's worst nuclear disaster since Chernobyl.
One of Tepco's biggest challenges is trying to contain radioactive water that cools the reactors as it mixes with about 400 tons of fresh groundwater pouring into the plant daily.
Tepco has been injecting a chemical into the ground to build barriers to contain the groundwater, but the method is only effective in solidifying the ground from 1.8m below the surface, whereas data from test wells shows the contaminated water has risen to one metre below the surface, the newspaper said.