Abstract: Spent nuclear fuel storage casks, particularly a protective and venting cover for such storage casks which are stored above ground. The protective and venting cover may be assembled from annular or doughnut-shaped cast concrete members stacked one upon the other and/or steel members extending the height of the storage cask. The annuli are axially indexed with respect to the storage cask, such that a venting annulus is formed about the storage cask and the annulus contributes to a defocusing geometry against armor piercing weapons, such an anti-tank "shaped charge" weaponry.

Abstract: Spent nuclear fuel storage casks, particularly a protective and venting cover for such storage casks which are stored above-ground. The protective and venting cover may be assembled from annular or doughnut-shaped cast concrete members stacked one upon the other. The annuli are axially indexed with respect to the storage cask, such that a venting annulus is formed about the storage cask and the annulus contributes to a defocusing geometry against armor piercing weapons, such as anti-tank "shaped charge" weaponry.

Abstract: A method of disposal of waste material on subaqueous ground is disclosed, and comprises transporting the material to a location above a selected site for disposal, conveying the material in a vessel to a level at, or close to, the subaqueous ground, and depositing the material onto the subaqueous ground. The vessel travels under free-fall conditions for part of its descent. Also provided is a vessel which comprises a generally cylindrical body comprising a containment area having an opening at its upper end for receiving material which is to be transported by the vessel, and having at its lower end means for permitting egress of the material.

Abstract: A method for disposal of material on subaqueous ground substantially without said material coming into contact with the surrounding water is disclosed. The method comprises positioning a ship carrying said material above a selected site for disposal, transferring said material to a container or vehicle adapted to transport said material to the subaqueous ground, conveying said material to a level at, or close to, said subaqueous ground and depositing said material from said container onto said subaqueous ground. The method can be used to deposit two materials one over the other--i.e. by capping--which is valuable where the first material is a contaiminated waste product, and the second is an uncontaminated waste product. A ship for use in the method of the invention is also disclosed.