Radiation-contaminated gravel shipped from a quarry in the evacuation zone around the Fukushima No. 1 nuclear plant found its way to an elementary school building as well as roads and pathways around houses, sources said Wednesday.

The gravel went into concrete that was used to make an elementary school in Nihonmatsu, Fukushima Prefecture, more resistant to earthquakes. The area where the gravel was used had a radiation reading of 0.1 to 0.2 microsieverts per hour.

"We are surprised at the news as we had never expected it. We'd like to make efforts to ensure children's health by checking the radiation level on a regular basis," the school's principal said.