Keywords:Fukushima Daiichi Nuclear Power Plant accident, in and around residential houses, temporal changes, former/current evacuation areas
With the lifting of evacuation orders and the certification of “Specific recovery and revitalization base area revival and revitalization plan", the numbers of the returnees are expected to increase. Information in line with the current situation becomes more important. In particular, information in and around residential houses is important since residents spend large portion of their time indoors. We have been investigated distribution of radioactive substances in and around residential houses for approximately 150 houses within former/current evacuation areas since 2012.In this study, we present the temporal changes inthe values of Reduction Factor, RF and in remaining indoor contamination for houses that have been investigated repeatedly.