The cleanup effort at Japan's crippled Fukushima nuclear power plant suffered another setback Tuesday when workers spilled four tons of radioactive water into the soil.
The Tokyo Electric Power Company (TEPCO) said on Tuesday that the accident occurred during the transfer of polluted rain water from one of the plant's concrete gutters to an empty storage tank.
TEPCO does not know the water's precise contamination level, but estimates it was not highly polluted. It said the water has soaked into the surrounding soil, raising the possibility that it reached groundwater.
The operator has had trouble storing the massive amounts of contaminated water it is using to cool the reactors that were damaged by the 2011 earthquake and tsunami.
In addition to the latest incident, the company has discovered several leaks in the specially built tanks meant to store the highly toxic water. Furthermore, groundwater flowing under the facility has been mixing with the toxic water and leaking into the nearby Pacific Ocean.
Japan's government recently stepped up its efforts to help TEPCO clean up and decommission the site, a process that could take decades. Two and a half years after the crisis began, tens of thousands of people remain displaced.