Retrievability in the Deep Geological Disposal motivation and implications

The final disposal of High Level Wastes (HLW) in a repository without the intention of retrieval has been the conceptual basis used by most countries to define their deep geological disposal concepts. As a result, current disposal concepts allow, but do not facilitate, the retrieval of the waste. The concept of retrievability has been introduced in the stepwise development process of the deep geological disposal for a series of ethical, socio-political, and technological reasons, which have structured a great deal of attention in the international community. At present, although no clear definition has been given to the term retrievability there seems to be a general consensus in respect of its interpretation as the capacity to retrieve waste from the underground facilities of the repository up to several years after its closure. The retrieval of the HLW packages from the disposal cells entails tackling a series of technological and operational constraints stemming, on the one hand, from the configuration and state of the repository at the time of retrieval and, on the other, from the environmental conditions of temperature and radiation in which such operations have to be carried out. Most countries, Spain included, are assessing the technical feasibility of retrieving waste during the different stages of the repository lifetime, exploring at the same time the possibility of implementing some changes in the repository's design, construction and operation without affecting its long-term safety. The purpose of this paper is three-fold (1) to identify the motivations that have led the international community to consider retrievability in the repository's stepwise development process, (2) to analyse, qualitatively, the different implications this has on current repository concepts, and (3) to state the current Spanish position. (Author)