Radiological impacts in Life Cycle Assessment - Part II: Comparison of methodologies

In a complementary article, an overarching framework was proposed to include radiological impacts in Life Cycle Impact Assessment (LCIA). Two methodologies were derived embodying the framework: the Critical Group Methodology (CGM), adapted from the approach commonly used in Human and Environmental Risk Assessment (HERA), and UCrad, based on the compartment modelling approach commonly used in LCIA. In this paper, characterisation factors obtained by the two methodologies are compared in detail to investigate the consequences of the different approaches to fate modelling and the sensitivity of the characterisation factors to the radionuclides' half-life. Characterisation factors from the CGM methodology are strongly affected by radioactive decay at low half-life and by dilution at large distances. Conversely, UCrad factors are not affected by dilution and are affected less than CGM by radioactive decay. It is concluded that UCrad is more appropriate than CGM for LCA because it is consistent with the general approach used in LCIA. However, CGM can be used alongside UCrad to make recommendations on the location and scale of specific processes emitting radionuclides.