Predicting the Performance of a Site Closure System Through Engineering Risk Assessment

Abstract

Since 1959 British Nuclear Fuels pie (BNFL) have operated a disposal site for solid low level radioactive wastes (LLW) at Drigg, approximately 6 kilometres south of Sellafield in West Cumbria. Prior to 1988 the disposal method involved the excavation of a series of parallel trenches across the site which were back filled with LLW and covered with an interim, water resistant cap. Since 1988 the disposal method has changed and waste is now compacted and placed into steel isofreight containers into which a highly fluid cement based grout is added prior to the containers being disposed of in a series of open concrete lined vaults. It is proposed that, when full, each vault will also be capped. The change in disposal method has extended the life of the site and final closure is therefore not anticipated until about the middle of the next century.