What challenge does reprocessing alleviate for a nuclear reactor?

Reprocessing spent nuclear fuel primarily addresses the issue of fission product buildup within the reactor. During nuclear fission, the reactants (fuel) are transformed into a variety of fission products, some of which can be highly radioactive and may have a detrimental effect on the reactor's operation if allowed to accumulate.

By reprocessing, these spent fuels can be treated to separate out the fission products, which can then be managed or removed from the reactor system. This alleviates the buildup of these materials, allowing the reactor to operate more efficiently and safely over a longer period. Furthermore, reprocessing can also recover usable uranium and plutonium, thereby contributing to the sustainability of fuel resources and minimizing the volume of radioactive waste that needs to be managed.

The other options, while related to nuclear power, do not directly connect to the key advantage provided by reprocessing. For example, while reprocessing can indirectly affect fuel supply and waste management strategies, its primary and most immediate benefit is in managing the accumulation of fission products within the reactor core.