Natural background radiation

ConclusionsThe data presented show that the yearly background dose equals on the average about 2 mSv (200 mrem). Two thirds of the dose is attributable to internal radiation from natural radionuclides—primarily the decay products of radon and thoron, entering the human body with inhaled air. The external irradiation is due approximately equally to cosmic radiation and natural γ emitters such as40K and radionuclides of the thorium and uranium series.Comparison with doses owing to the use of artificial radionuclide and other sources of ionizing radiation (Fig. 5) indicates that their contribution is insignificant. Amongst them diagnostic use of radiation (0.4 mSv) still predominates. The dose owing to nuclear tests in the atmosphere, which in 1963 reached approximately 7% of the average yearly dose owing to natural sources, is now less than 1%. The contribution of nuclear power in the first half of the 1980s did not reach 0.1% and, if forecasts of the growth of nuclear power are realized, by the year 2000 it will not exceed 1% of the background dose.Judging from reports by Soviet experts [7–9], the accident at the Chernobyl nuclear power plant will increase insignificantly the collective dose to the population of the European part of the USSR and will not affect the validity of the last conclusion: the dose due to nuclear power up to year 2000 will not exceed 1% of the background dose.