Ionizing radiation potential in life cycle impact assessment: broadening the assessment through inclusion of radioactive decay products

Abstract Purpose This work briefly reviews the fate, exposure, and effect modules of established ionizing radiation potential (IRP) impact categories and proposes an IRP methodology with the novel inclusion of radioactive decay products (i.e., progeny), referred to as Clemson University Radiological Protection (CURP). Methods CURP reports characterization factors (CFs) and midpoint dose factors (MDFs) and is comparable to (1) methods established for other impact categories and (2) those used in radiological risk assessment. Consistent with the previously established UCrad approach, USEtox was used to determine the environmental steady-state concentrations. US EPA tools were used to determine the contribution of radioactive progeny to the collective effective dose rate from air submersion, water immersion, ground irradiation, ingestion, and inhalation. These dose rates were then integrated over time to calculate the total collective effective dose. Results and discussion The CFs for a majority of the 113 radionuclides characterized in CURP remained constant or decreased as time increased ( 238 U had a maximum increase on the order of 10 −5 ). The percent difference between MDFs with and without progeny inclusion demonstrates that the progeny can have a significant influence on the overall impact. For example, the percent difference in MDFs for 222 Rn with and without progeny is 198% by 1000 years for all emissions. Other radionuclides have small changes at lower time horizons that become more pronounced as the time horizon increases; an atmospheric emission of 226 Ra and 235 U yields a percent difference in the MDFs of ~ 0.2% and ~ 0.5%, respectively, at a time horizon of 0.01 years and 155% and 134%, respectively at 10,000 years. Conclusion Ultimately, the time horizon and progeny inclusion can have drastic implications for the resulting MDF, and consequently the CFs. Thus, interpretation of results needs to be carefully considered due to the heavy dependence of time for IRP, especially when considering releases to the continental and global scale or based on a method using steady-state assumptions. Graphical Abstract