Natural background radiation intensity inside and outside a highland Tibetan private house (I)

The radiation exposure rates were measured inside and outside a private house in the Tibetan Autonomous Region of China. As far as seen from the cosmic ray exposure rate and the gamma ray exposure rate, the indoor exposure rates can be classified into 3 groups: the 2nd floor, entrance to the 1st floor and in the rest of the 1st floor. In the 1st group, the mean cosmic ray exposure rate was 4.079 nC/kg/h (15.81 μR/h) and the mean gamma ray exposure rate was 4.515 nC/kg/h (17.50 μR/h). In the 3rd group, the mean cosmic ray exposure rate was 2.740 nC/kg/h (10.62 μR/h) and the mean gamma ray exposure rate was 5.284 nC/kg/h (20.48 μR/h). The reason why the cosmic ray exposure rate in the 3rd group is lower than in the 1st group is believed to be that cosmic rays are cut off by the construction materials. The reasons why the gamma ray exposure rate in the 3rd group is higher than in the 1st group are believed to be that the 3rd group is nearer to the ground than the 1st group and the stones of which the 1st floor walls are made have a higher concentration of natural radionuclides than the earth of which the 2nd floor walls are made. Both the cosmic ray exposure rate and the gamma ray exposure rate in the 2nd group are between those of the 1st group and the 3rd group. Furthermore, the authors calculated the air absorbed dose rates inside and outside a Tibetan private house and compared them with those of private houses in the world. (author)