2013 年 35 巻 3 号 p. 73-79
The March 11 earthquake and tsunami crippled the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company. Consequently, wide areas were contaminated with radioactive substances. The evacuation zone was set as the area within a 20 km radius from the power plant. People who lived in that zone were forced to evacuate immediately. Fukushima Prefectural Disaster Headquarters (FPDH) and the Japanese Governmental Disaster Headquarters (JGDH) planned to let them return to their homes temporarily and asked for help from related organizations, one of which is the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan. The ministry asked all Japanese universities and colleges to take part in screening radioactivity of the temporal returnees from the areas, with aids of the temporal returning program. We applied to the screening activities and measured radioactivity of the returnees at Bajikoen Off-site Center on July 14-17, 2011, and at Kawauchi Gymnasium or Hirono Central Gymnasium Off-site Center on July 23-25, 2011, in Fukushima Prefecture. During these periods, 4009 returnees in all were screened at these three Off-site Centers. None was found to be contaminated with radioactivity over 13,000 cpm. Before the returnee screening program, emergency screening had been conducted soon after the disaster. In all, 33,598 people out of 78,000 evacuees (43%) were screened during March 12-December 7, 2011, during which 3,686 volunteers were recruited by MEXT for the screening program. This is a tiny fraction of the temporal returning program. FPDH reported that 102 people were contaminated with more than 100,000 cpm out of 259,108 people generally screened from March 13, 2011-October 10, 2012. The 102 were detected only in the screening in March in 2011. No hazardous effect, however, was detected among them, so far. Screening is still underway. The present article was compiled to record aspects of the large scale radioactivity monitoring program planned by FPDH and JGDH.
