Storage is a means of modifying the way radioactive waste packages are managed over time, mainly by allowing the non-reprocessed spent fuel and the vitrified waste packages to cool down. This is the solution currently being used for the most highly radioactive waste, until a disposal facility is built. But could this role continue for periods of more than a century? The possibility of a storage facility lasting longer than a hundred years has not been proven, and consequently this cannot be guaranteed.
In 1991, when the Bataille Act on radioactive waste was passed, the alternatives were either to renew existing industrial facilities at the end of their life, or to decide immediately to deal with storage periods of several centuries by building storage facilities designed to last that long. A middle way was defined in 1998. This consisted of studying the durability of the most recent industrial storage facilities and issuing recommendations if it was felt that extending their life was appropriate.
When they were designed, the storage facilities currently in operation were scheduled to operate for only around fifty years. They are likely to have to accommodate all the primary packages of reprocessing waste from the current reactor fleet. Experience with operating these facilities has shown that they could be used for storage for up to a hundred years.
When they were designed, the storage facilities currently in operation were scheduled to operate for only around fifty years. They are likely to have to accommodate all the primary packages of reprocessing waste from the current reactor fleet. Experience with operating these facilities has shown that they could be used for storage for up to a hundred years.
Research into the storage of packages of current reprocessing waste by extending the life of recent industrial storage facilities suggests that this type of storage would be safe for periods of around a century. Only the block diagrams and preliminary designs have been produced for new types of facility that can store waste for up to 300 years. To move beyond the preliminary design stage, a potential storage site would have to be selected. The choice of site is crucial for subsurface facilities, particularly to check the compatibility of the host rock with the storage facility being designed (compatibility of the water percolating through the rock with the concrete, thermomechanical effects, hygrometry, etc.).
The CNE's conclusions
According to the French National Evaluation Commission (the CNE), 'long-term storage is chiefly a matter of engineering. Regardless of which option is chosen, it cannot be used for periods of more than a century without constant monitoring, maintenance and protection. Periodic operations to upgrade the facilities would become increasingly difficult with longer and longer storage periods. We are a long way from storage without the need for careful monitoring.'
The outcome of research into the surface or subsurface storage of waste, with the intention of retrieving that waste, depends on the envisaged storage period. If it is less than a century, which is enough to allow the current high-level long-lived waste to cool down, industrial storage facilities exist at La Hague and could be extended. The same goes for ILW-LL waste. If it is longer (e.g. 300 years) the issue needs to be taken into account of the durability of the storage structures to be built. No acceptable solution to this has yet been found.
The CNE adds: Without wishing to prejudge social stability in the long term, long-term storage places a heavy burden on future generations, which will also have to decide the ultimate fate of the waste.
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