Storage of waste and spent fuels

In the nuclear sector, as in all industrial fields, storage is an essential "buffer" function in process management. One of the parameters that helps define storage concepts is the duration of this stage. This is either linked to the duration of the political and industrial phases involved in building long-term management facilities (i.e. storage facilities), or to the duration chosen to optimize processes. These two approaches can coincide quite well.

Thus, the role of storage is not only to enable the necessary decoupling of the various stages of spent fuel and waste management. This stage also contributes to overall industrial optimization, in particular by allowing short-lived radionuclides to decay sufficiently to facilitate the industrial stage that follows storage: the best example of this is the few years required before spent fuel can be recycled. Similarly, in France, storage facilities have been set up as part of the national radioactive materials and waste management plan to allow the tritium in certain types of waste to decay sufficiently. Finally, the thermal character of the packages to be stored in deep geological repositories is a central parameter of the disposal concept and of safety analyses: a waiting period of around fifty years is often deemed necessary for high-level waste, before it can be disposed of in deep geological repositories.

The considerable feedback we have accumulated on spent fuel and waste repositories confirms the very high level of safety and maturity of our techniques. This is a very important factor in the robustness of nuclear power generation, given the difficulties sometimes encountered in obtaining complete long-term management systems. Storage enables these potentially hazardous substances to be "guarded" over time, without any impact on health or the environment, which means that we can take the time needed to develop accepted solutions.

In the case of spent fuel, the main stage consists of waiting, from a few years (in the case of processing for recycling) to several decades (in the case of an as-is storage strategy). Let's make it clear from the outset that we will be distinguishing between buildings, or warehouses, and the function they perform, i.e. storage proper.

Waste can be either unprocessed (before treatment and packaging) or packaged (in the form of waste packages): it is this type of waste that will be discussed here. Waste is stored prior to transport to other repositories, or prior to final disposal. In France, waste management is governed by the law of June 28, 2006.

Warehouse concepts must therefore fulfill a number of functions. The first is reversibility. This is what distinguishes a repository from a final storage facility...