Clearly, the requirements for maintaining active control are very much greater for storage concepts which have been suggested for HLW/SF. At one extreme are engineered stores which are maintained for millennia by an ‘‘atomic priesthood’’ (Buser, 1998). When reviewed, such proposals read more like wishful thinking or science fiction than a serious evaluation of a real hazard. It indicates a strange view of history (or a complete lack of its consideration) when more confidence is placed in the longevity of a church of holy guardians than 25 cm thick steel inside an impermeable clay at a depth of several hundred metres. Luckily, the recent increasing concern about terrorist vulnerability (although greatly over-stated) is tending to remove such schemes from further consideration.

Although superficially more robust, similar underground controlled/indefinite storage concepts suffer from the same inherent societal problems. For example, the dry rock deposit (DRD) concept of Cronhjort et al. (2003) for in-hill, drained storage of SF has been proposed as a solution to the possible disruption of a deep geological repository in Sweden due to rebound earthquakes resulting from glacial unloading after the next ice age (in several tens/hundreds of thousands of years). Of course, such a surface store would be destroyed in a much shorter time by the glaciers. The solution to this – the ‘‘guardians’’ would move the store! How this would be done and where it would be moved to is not specified. With an icesheet about to cover the whole of Northern Europe, it appears most unlikely that an old waste depot will be top of anyone’s priorities (see also comments in McKinley and Murnier, 2003; Mo¨rner, 2003)!

Apart from such rather poorly thought-out ideas, there are some sound technical reasons for delaying final disposal of waste:

There may be a problem with the site concept which is not detectable with present technology.

Technology may develop to provide a better management option.

The waste may be a resource which can be utilised in the future.

These arguments (especially the first two) are rather vague and run counter to the ethical principle that the generation benefiting from nuclear power/technology should take responsibility for management of the resulting waste (see also comments in Chapter 7). Nevertheless, a case can be made – particularly for ‘‘declared waste’’, like SF or weapons U/Pu, which could certainly be recycled with existing technology, even if this is constrained by economic and/or political boundary conditions. This has led to the idea of combined deep storage with disposal, where a deep underground facility may serve as an open store for an extended period of time, yet can be sealed to act as repository whenever a decision is made to do so (i.e., the CARE concept, see below). This is, however, considered as a variant of deep geological disposal and hence is covered in section 3.5.2 below.

3.5. Alternatives to conventional repositories

3.5.1. Introduction

Despite the numerous options for implementing a conventional mined geological repository, the general opposition to such projects or the constraints set by the high costs involved may bring up the question of alternatives (Fig. 3.1) – particularly for national