External natural radiation level and population dose in Xinjiang

A survey of external exposure dose rates from natural radiation in Xinjiang was performed in 1983 by using FD-71 scintillation radiometers and RSS-111 high pressure ionization chambers. The average absorbed dose rates in air at 1 m above the ground from terrestrial irradiation and from cosmic rays were estimated to be 8.5 x 10-8 Gy.h-1 and 4.5 x 10-8 Gy.h-1 for outdoors, an 7.8 x 10-8 Gy.h-1 and 4.3 x 10-8 Gy.h-1 for roads, respectively. A high background region has been found in the Pamirs. Its average absorbed dose rates from terrestrial radiation were determined to be 25.3 (19.0-31.3) x 10-8 Gy.h-1 for outdoors and 33.6 (26.6-48.2) x 10-8 Gy.h-1 for indoors. The annual effective dose equivalent from both terrestrial radiation and cosmic rays is 1,040 Sv, and the annual collective dose equivalent from same radiation soutces is 1.36 x 104 man.Sv