DESIGN CONSTRUCTION OF A STORAGE FACILITY FOR INTERMEDIATE LEVEL WASTE AT HUNTERSTON A DECOMMISSIONING SITE

摘要

Hunterston A Decommissioning Site (UK) is required to process and store on site, both operational and decommissioning raw Intermediate Level Waste (ILW), encapsulated within some 1578 packages, until such time as a National Repository becomes available. These will be standard NIREX specification stainless steel 3m{sup}3 boxes and drums, containing the solid, sludge and resin wastes in a monolithic matrix of cementitious grout. The boxes will be used for solids and the drums for sludges and resins. The wastes are thus stabilised and passively immobilised in the packages, which are largely unshielded. The store comprises a single vault, above ground, concrete structure serviced by a Package Handling Machine (PHM) and designed for an operating life in excess of 100 years with minimal through life maintenance. The store structures provide the necessary public and operator shielding protection. Packaging of the wastes is the responsibility of separate projects, as is transport from these facilities to the store. The latter is by a proprietary transporter fitted with a top loading shielded container. The store design is intended as a generic solution suitable, with only minor modifications, for ILW storage on all Magnox reactor sites, and other possible applications. The paper describes the development of the design from the concept design to a fully substantiated design with an approved Pre Construction Safety Report and illustrates some of the more significant issues, which evolved, and the nature of their resolution. The project delivery is undertaken by the ILW Store Alliance which consists of Balfour Beatty (civil engineering construction), British Nuclear Group (management, design authority and safety), Weir Strachan and Henshaw (plant design, manufacture, installation and commissioning) and Halcrow (civil and structural design). The paper outlines the operation of the ILW Store Alliance, the programme of works, detailst he manufacturing, assembly and installation processes along with the civil construction sequence. Site preparation and construction commenced during 2004, with mass concrete in-fill up to the building base slab level being completed. Building construction is now well advanced, with LT rail installation ongoing. The Mechanical and Electrical equipment manufacture/procurement is well underway with major items such as receipt and inspection cells, PHM and MASD systems complete and HVAC & control room plant procurement ongoing. The next milestone safety submission will be the PICR, prior to inactive commissioning, programmed for completion in late 2006. Hand-over of the store to Site is scheduled for mid 2007.