Application of the radiation equivalence principle to estimation of levels of radiological protection of the population: risk-oriented approach

The present concept of the development of nuclear energy is based on the use of fast nuclear reactors with closed nuclear fuel cycle and new technologies, ensuring nuclear safety and radiological protection of present and future generations of people and the environment from ionizing radiation. For these purposes it is important to keep the natural radiation balance, it means that in some time the total radiotoxicity of the spent nuclear fuel will not exceed the total radiotoxicity of natural raw uranium ore. In this connection it is necessary to adhere to the radiation equivalence principle that allows estimation of levels of radiological protection of the population while storing spent nuclear fuel. The article presents methods for calculation of the decay time of spent nuclear fuel (SNF) in the compliance with the radiation equivalence principle. The first method is based on the comparison of committed effective doses from SNF and natural uranium and, the second method is based on comparison of corresponding lifetime attributable radiation risks calculated for the Russian population. The decay time of spent nuclear fuel from the BREST and VVER reactors is calculated. The following main results are obtained. The committed effective dose from internal exposure to various radionuclides is a rough indicator of possible radiation risk and potential radiotoxicity of the radionuclides. While adhering to the radiation equivalence principle, the use of the committed effective dose as a measure of potential radiotoxicity is acceptable, because this approach overestimates the necessary decay time of SNF as compared with potential radiotoxicity estimate based on lifetime attributive risk. Radiotoxicity of SNF from VVER is higher than radiotoxicity of SNF from BREST. The maximum difference in lifetime attributable risks from exposure to VVER SNF and BREST SNF will be when the decay of spent fuel time is 100 years on average, the difference is higher for women than for men.