What is a significant disadvantage of ion exchange in terms of the media used?

The chosen answer highlights a notable limitation of ion exchange processes. In ion exchange systems, the resin or media used to capture specific ions from water or other solutions becomes saturated after a certain capacity is reached. Once saturated, the media loses its ability to effectively remove additional ions, which means it cannot continue to perform its intended function until it is either regenerated or replaced.

While some ion exchange media can be regenerated, this process can involve complex steps and chemicals, thus adding operational challenges. In terms of reusability, saturation effectively means that the media's usefulness is compromised, and it typically requires external intervention to restore its efficacy, reinforcing the significant downside regarding its continued use post-saturation.

In contrast, other options might suggest different limitations associated with ion exchange media, but they do not capture the essence of the correct answer as directly or effectively as the limitation of saturation. This is a critical understanding in the realm of nuclear power engineering, especially when considering the efficiency and sustainability of water treatment processes within nuclear facilities.