A framework for including enhanced exposure to naturally occurring radioactive materials (NORM) in LCA

Purpose

Despite advances in the development of impact categories for ionising radiation, the focus on artificial radionuclides produced in the nuclear fuel cycle means that the potential impacts resulting from increased exposure to naturally occurring radioactive materials (NORM) are still only covered to a limited degree in life cycle assessment (LCA). Here, we present a potential framework for the inclusion of the exposure routes and impact pathways particular to NORM in LCA.

Methods

We assess the potential magnitude of enhanced NORM exposure, particularly in light of the potential use of NORM residues in building materials, and set out the potential exposure routes that may exist. We then assess the current state of the art, in terms of available fate, exposure and damage models, both within and outside of the LCA sphere. Finally, these exposure routes and modelling techniques are combined in order to lay out a potential framework for NORM assessment in LCA, both in terms of impact on humans and ecosystems.

Results and discussion

Increased exposure to NORM radionuclides can result either from their release to the environment or their proximity to humans as they reside in stockpiles, landfills or products. The exposure route via products is considered to be increasingly significant in light of current attempts to incorporate technologically enhanced NORMs (TENORM) including bauxite residue into building materials, by groups such as the ETN-MSCA REDMUD project. Impact assessment models for NORM exposure are therefore required to avoid potential burden shifting in the assessment of such TENORM products. Models describing the fate of environmental releases, the exhalation of radon from building products and the shielding effects on landfills/stockpiles are required to assess potential exposure. Subsequently, models relating exposure to radiation sources and the effective internal and external dose received by receptors are required. Finally, an assessment of the damage caused to the receptors is desirable.

Conclusions

A sufficient suite of currently existing and internationally recognised models exist that can, with varying degrees of modification, form the building blocks of a comprehensive NORM characterisation method for LCA. The challenge ahead lies in consolidating these models, from disparate fields, into a coherent and generally applicable method for the assessment of enhanced NORM exposure in LCA.