Radioactive decay of 90Sr in cement: a non-equilibrium first-principles investigation

Cement is an inexpensive and relatively easily manageable material that is used as a last barrier for nuclear waste disposal. Under these conditions, the cement is in contact with low radiation doses, but there is a distinct possibility of being contaminated with radioactive products. Of particular concern is the medium lived half-life product Sr-90 (28.8 years) due to its ability to replace Ca. Sr-90 undergoes beta-decay to Y-90 which, in turn, beta-decays to stable Zr-90. In this work, we discuss systematically the chain of non-equilibrium processes that result as a consequence of beta-decay events in cement. We first use density functional-based methods to study the consequences of the sudden increase of the nuclear charge from Z to Z + 1, a possible induced ionization and the perturbation of the surrounding electronic charge. Secondly, we use molecular dynamics simulations to study the recoil of the daughter nucleus. Finally, we discuss the damage caused by the ionization cascade produced during the propagation of the beta-electron and the resulting chemical and structural perturbation.

Automated summary

Cement, as a barrier for nuclear waste disposal, may be contaminated with radioactive products, particularly Sr-90. Research has shown that beta-decay events in cement can lead to a series of non-equilibrium processes, causing perturbations in surrounding electronic charge and chemical/structural changes.