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[en] The decommissioning of nuclear facilities calls for the controlled removal of activated and/or contaminated materials from the inside of biological shielding structures whilst relying on the outer layers of non-activated or contaminated material to contain the activity. This paper describes development work being carried out on the controlled use of explosives to cut and remove selected parts of biological shielding structures without impairing the overall containment integrity. The technique being developed is also applicable to other controlled cutting of concrete requirements outside the nuclear industry. The paper reviews work carried out to optimise the concrete cratering effectiveness of the explosive charges and reports on investigations carried out on concrete removal from re-entrant corners, on curved surfaces and from behind reinforcement and steel liners. Procedures for achieving a required level of material removal without impairing the remaining structure are reported. The use of explosives for the provision of charge holes is discussed together with reports on tests to assess the particle size distribution in the dust generated during blasting. To substantiate and to add credibility to the development work being carried out, analytical studies have been performed to investigate the effects of firing an explosive charge buried in a concrete mass. The paper describes analytical results from this exercise and compares the results with experimental results from field trials. (author)

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[en] Nuclear explosives afford diverse tools for managing our water resources. These include principally: the rubble column of a fully contained underground detonation, the similar rubble column of a retarc, the crater by subsidence, the throwout crater of maximum volume (the latter either singly or in-line), and the ejecta of a valley-slope crater. By these tools, one can create space in which to store water, either underground or on the land surface - in the latter instance, to a considerable degree independently of the topography. Underground, one can accelerate movement of water by breaching a confining bed, a partition of a compartmented aquifer, or some other obstruction in the natural 'plumbing system'. Finally, on the land surface, one can modify the natural pattern of water flow, by canals excavated with in-line detonation. In all these applications, the potential advantage of a nuclear explosive rests chiefly in undertakings of large scale, under a consequent small cost per unit of mechanical work accomplished

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[en] Two-dimensional calculations have been done to determine the feasibility of constructing deep canals with nuclear explosives subject to the limitation in the proposed PNE Treaty. The conditions under which a series of explosives set in a row can be approximated by a cylindrical line source have been determined. Using this result, the possibility of lifting 250 m of overburden with 150-kt charges spaced at 50-m intervals has been investigated. This study shows that for a variety of equations of state for the geological medium, there appears little possibility that such an excavation can be accomplished

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[en] Crater data have been examined from recent hypervelocity impact and chemical explosion experiments conducted in accelerating frames. Data have been identified from experiments for which the conditions of similitude have been very nearly achieved. Examination of these data from similar experiments indicates that fourth-root or gravity scaling is the rule which best relates crater dimensions to the energy release of impacting projectiles or explosives. Implications for chemical and nuclear explosion cratering are that in model experiments where the gravitational field is constant the specific energy and dimensions of the explosive must be scaled as the fourth-root of explosion energy release. Additionally, medium properties must be appropriately scaled in similar experiments. Because of the impracticability of realizing the constraints imposed on model experiments by similitude requirements attention in future experiments should be focused on the sources of similarity violation and their influence on empirical relationships derived from experiments. Experiments in accelerating frames with both explosive sources and hypervelocity impact projectiles offer one means for investigating effects of similitude violation. To further elucidate the question of crater scaling, experiments in accelerating frames may be conducted which most nearly achieve the conditions of similitude required