Investigation of environmental natural penetrating radiation level in Hebei province

The methods and results of the investigation on natural penetrating radiation level in Hebei Province from 1985 to 1987 are presented. 285 25 x 25 km-netted measuring points were set unformly up all over the porvince, with 204 densely measuring points of different types added. The results show that: (1) The point-weighted, area-weighted and population-weighted average value of natural γ radiation dose rate for field is 5.59, 5.51 and 5.31 x 10-8 Gy·h-1, respectively; (2) The point-weighted and population-weighted average value of the dose rate inside buildings from cosmic ray is 3.05 and 2.80 x 10-8 Gy·h-1, and outside buildings is 3.38 and 3.11 x 10-8 Gy·h-1, respectively; (3) The point-weighted and population-weighted average value of natural penetrating radiation dose rate inside buildings is 12.44 and 11.97 x 10-8 Gy·h-1, outside buildings is 8.97 and 8.42 x 10-8 Gy·h-1, respectively; (4) The annual effective dose equivalent from natural γ radiation, cosmic ray and natural penetrating radiation is 0.50, 0.25, and 0.75 mSv, respectively; and correspondingly, the annual collective effectiv dose equivalent is 2.7, 1.3 and 4.0 x 104 man·Sv, respectively