Abstract
^<222>Rn entry characteristics into a basement (room volume : 30.7 m^3, penetration holes : 11 points in the surrounding wall) was investigated. The ^<226>Ra contents of the soil surrounding the house and the concrete were 26.2 and 25.9 Bqkg^<-1> respectively. Main results of the experiment were as follows : 1) A very small pressure difference (0.3 Pa) caused by the chimney effect drove the soil gas, including Rn, into the basement. 2) The Rn emanation power of the concrete increased from about 7 % at 10℃ to about 27 % at 20℃ wall temperature. 3) The maximum Rn entry rate was approximately 150 Bqm^<-3>h^<-1> when one penetration hole was opened and was approximately 300 Bqm^<-3>h^<-1> when four holes were opened in the wall around the basement.
