Fukushima nuclear plant: Toxic isotope found in groundwater
High levels of a toxic radioactive isotope have been found in groundwater at Japan's Fukushima nuclear plant, its operator says.
Tokyo Electric Power Company (Tepco) said tests showed strontium-90 was present at 30 times the legal rate.
The radioactive isotope tritium has also been detected at elevated levels.
Rupert Wingfield-Hayes reports from Japan.