Possible future trends of radiation exposure by carbon 14.

The possible future trends of the radiation exposure by carbon 14 have been assessed. The individual lifetime doses and the European and global dose commitments were calculated by a specific activity model. A non-linear compartment model was developed so simulate the global cycling of carbon dioxide from the combustion of fossil fuels and of radiocarbon released from nuclear energy facilities until the year 2200. The energy scenarios considered are: (I) logistic growth functions for energy supply with fossil fuels; (II) a high, low and moderate estimate for the extension of nuclear energy (light water reactors). In addition, the influence of the retention of C-14 in the fuel reprocessing plant effluents was tested. For most of the scenarios considered the increase of the specific activity by C-14 releases is more than compensated by the CO2 releases from fossil fuels. Up to 2200 individual lifetime dose commitments for 70 years were found between 0.85 and 0.45 mSv (pre-industrial value: 0.73 mSv). The anthropogenic contributions to the global collective dose commitments until the year 2100 were estimated (for the moderate scenario without retention) at 1.27 X 10(6) man-Sv (11%) from nuclear weapon tests, 3.5 X 10(5) man-Sv (3%) from nuclear power plants, and 6.5 X 10(5) man-Sv (5.6%) from fuel reprocessing facilities.