Abstract
Comparisons of natural radiation at the new and the old campus of Fukushima Medical College have been made for three types of measurement: (1) gamma dosimetry using photon-counting thermoluminescent dosimeter; (2) gamma spectrometry using germanium semiconductor detector; (3) measurement of atmospheric radon daughter concentrations using alpha spectrometry and G. M. tube. After our college moved, the gamma dose was reduced. Total counts and each peak count in gamma spectrum also were reduced except for thoron daughter peaks. Indoor atmospheric radon daughter concentrations were drastically reduced, while the outdoor concentrations remained the same level. Indoor G. M. tube background also was reduced. Annual effective dose equivalent from gamma rays and radon daughters was estimated to be 1.14mSv and 0.57mSv for the new and the old campus, respectively.
