The nuclear fuel cycle

The spent fuel unloaded from reactors at nuclear power plants may be managed in different ways, each of which is known as a cycle.

Open cycle

The spent fuel is considered to be a high level radioactive waste and is managed as such, being stored at specific temporary facilities. The operating lifetime of these storage facilities varies from one country to the next but may be between 50 and 100 years.

The definitive destination of the spent fuel will be a deep geological disposal facility, which will mark the end of its treatment as a waste.

Closed cycle

The spent fuel is partially reused by means of reprocessing.

This consists of recovering those components of the used fuel that still have an energy potential, fundamentally uranium and plutonium, for their reuse in a reactor. This fuel, formed by oxides of plutonium and uranium, is known as MOX (mixed oxide fuel) and may be reprocessed again.

In the closed cycle, the rest of the components of the spent fuel (fission and activation products and other actinides) are conditioned and transported to a temporary storage facility.

As in the case of the open cycle, the final management of these components consists of their emplacement in a deep geological formation.