Temporary storage

A temporary solution

Interim storage is a temporary solution that plays a central role in the management of the most highly radioactive materials: spent reactor fuel and, in France, vitrified waste resulting from reprocessing such fuel. Storing spent fuel and waste for several years allows heat release and radioactivity to subside. In the case of spent reactor fuel, this decrease facilitates reprocessing operations.

Interim storage also features in the final management phase. Products are stored not only to allow them to cool, but also as an interim solution pending definition of the final destination for vitrified reprocessing waste, which will probably be underground disposal in deep-lying geological layers. Storing waste for longer will enable the necessary final repository facilities to be smaller. Interim storage is planned for periods of several decades. To this end, in France, the most radioactive waste is currently stored at facilities in Marcoule and especially La Hague.

There are storage periods at several stages during reprocessing. Recently-unloaded spent fuel is first stored in a pool close to the reactor, before being transported to La Hague, where it is stored in another pool in which it will be allowed to cool for several years pending reprocessing. Lastly, after separating out the uranium and plutonium, vitrified waste from the reprocessing operation is stored in ventilated shafts pending final disposal.

Non-reprocessed spent fuel continue to be stored in pools at La Hague, pending a decision on its fate.

In a country such as the United States, which does not currently reprocess its spent fuel, waste has remained in storage in reactor pools or dry silos for more than 30 years in some cases. This radioactive waste was intended to be transferred to Yucca Mountain, a huge repository located deep under the Nevada desert. However, after many years of hesitation, this huge project was abandoned in 2010 by the Obama administration. This decision has sent the United States back to the drawing board regarding the management of this radioactive waste, which remains dispersed among the country’s power plants.

Sweden, which does not reprocess its fuel, has built the CLAB storage facility in Oskarshamn, featuring large interim storage pools 30 m underground. This facility will be used until a repository is built.

In France, intermediate-level waste must also be stored, only 36% of which has been conditioned, with the remainder awaiting recovery and processing. Some legacy waste must also be dealt with, for example waste from the earliest power stations using the graphite gas process, which is stored in Marcoule. The ongoing process of dismantling retired power plants also produces low-level long-lived waste, which is being held in interim storage pending definition of a final management strategy.