Overview of Design of Modular Vaults for the Storage of Low Level Nuclear Waste in the UK
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Overview of Design of Modular Vaults for the Storage of Low Level Nuclear Waste in the UK Eugene M Gallagher1 and Neil Shaw2 1 Coffey Geotechnics Ltd, Atlantic House, Simonsway, Manchester, M22 5PR, UK 2 Low Level Waste Repository Ltd, LLWR, Drigg, Holmrook, Cumbria, CA19 1XH, 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.
INTRODUCTION The Low Level Waste Repository (LLWR) is the UK’s principal facility for the disposal of LLW. It is a near surface facility located on the West Cumbrian coast and about 0.5 km inland, close to the village of Drigg. The site is currently operated under the terms of an authorisation granted by the Environment Agency under the Radioactive Substances Act 1993. Typically LLW disposed at the Drigg site consists of towels, paper, cardboard, plastic sheeting and containers, protective clothing, electrical cabling, scrap metal and process waste containing of radioactive substances. Wastes are received from a wide range of facilities including nuclear power stations, nuclear fuel cycle facilities, isotope manufacturing sites, universities, hospitals, general industry and the clean up of radioactively contaminated sites. Disposal operations at the LLWR site began in 1958, with waste being tumble-tipped into lined trenches (Trenches 1-7) until 1995. The first disposal vault (Vault 8) at the site commenced operations in 1988 and is still in use (although approaching capacity). Construction of a series of Modular Vaults (Vaults 9-15) has been planned, providing capacity for LLW until around 2070. The lifecycle of LLWR broadly consists the following three phases [1]: Operations Phase: now until circa 2070 (or until full): During this phase waste is being placed in the vaults. All site monitoring systems are operational and operators are present on site. In
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