Overview of Design of Modular Vaults for the Storage of Low Level Nuclear Waste in the UK

Abstract

Low level nuclear waste (LLW) will be stored in a series of modular vaults at the UK's principal LLW repository located near the village of Drigg in west Cumbria. The design of the new vaults is reviewed in the context of likely volume, composition and packaging of future waste streams; planning and regulatory considerations; and the site's geological and hydrogeological setting. Site construction work for the first of the new vaults (Vault 9) commenced in September 2008 and is anticipated to be substantially complete by the end of 2009 with future vaults constructed as required. The vaults are designed as a series of containment cells comprising a composite basal and sidewall lining system with an engineered capping system. Provision has been made for an extensive, deep cut-off wall as part of the longterm containment system for the whole repository site, which includes areas where LLW was historically tumble tipped into a series of trenches. Constraints on the design of the vaults include a complex hydrogeological setting controlled by two groundwater bodies influencing maximum excavation depth; geometrical limitations on the height, level and plan extents to which LLW could be stacked within the vaults; and strict limitations on the movement of construction materials by road.