The newspaper said experts from a private research center showed a high content of strontium in the soil samples and clay taken from a gutter of the building. This is the first case of detection of radioactive strontium in excess of 100 km of the rugged Central. Local authorities plan to conduct further analysis.
Strontium-90 is a highly radioactive beta emitter.
The accident occurred on March 11 in the central Fukushima-1 led to several radioactive leaks at the site. The authorities evacuated the population living within 30 km around the plant.
Traces of radioactive iodine and cesium were detected in soil, sea water and food not only in Fukushima Prefecture but also in surrounding areas.