Tokyo Shimbun issued the survey data obtained from the Ministry of Education, Culture, Sports, Science and Technology about the amount of radioactive materials detected in 24 hours in Tohoku area and prefectures of Kanto region till 5 p.m. May 17.

According to it, radiation in Tochigi Prefecture was 0.07 millisieverts per hour, again exceeding the highest level in ordinary times while that in Ibaragi and Saitama prefectures rose to 0.103 millisieverts per hour and 0.06 millisieverts per hour.

It is reported that radiation in Namie Cho, Fukushima Prefecture was 17.8 millisieverts at 11:23 May 17.

Radioactive materials exceeding the tolerance level were detected in oak tree mushroom and bamboo shoots cultivated in Fukushima Prefecture amid the amount of radiation constantly rising in the quake-ravaged areas.

The TEPCO, quoting the results of analysis, clarified that the nuclear fuel of No. 1 reactor of the Fukushima Nuclear Power Plant was proved to have been totally exposed and melted down five hours after mega quake and ensuing tsunami.

It was so far considered that the nuclear fuel meltdown started on March 12.