  Concrete, a mixture formed by mixing cement, water, and fine and coarse
mineral aggregates is used in the construction of nuclear power plants (NPPs),
e.g., to construct the reactor cavity concrete that encases the reactor
pressure vessel, etc. In such environments, concrete may be exposed to
radiation (e.g., neutrons) emanating from the reactor core. Until recently,
concrete has been assumed relatively immune to radiation exposure. Direct
evidence acquired on Ar$^+$-ion irradiated calcite and quartz indicates, on the
contrary, that, such minerals, which constitute aggregates in concrete, may be
significantly altered by irradiation. Specifically, while quartz undergoes
disordering of its atomic structure resulting in a near complete lack of
periodicity, i.e., similar to glassy silica, calcite only experiences random
rotations, and distortions of its carbonate groups. As a result, irradiated
quartz shows a reduction in density of around 15%, and an increase in chemical
reactivity, described by its dissolution rate, similar to a glassy silica;
i.e., an increase of around 3 orders of magnitude. Calcite however, shows
little change in dissolution rates - although its density noted to reduce by
around 9%. These differences are correlated with the nature of bonds in these
minerals, i.e., being dominantly ionic or covalent, and the rigidity of the
mineral's atomic network that is characterized by the number of topological
constraints (n$_c$) that are imposed on the atoms in the network. The outcomes
are discussed within the context of the durability of concrete structural
elements formed with calcitic/quartzitic aggregates in nuclear power plants.
