Radiological Characterisation of Facilities Undergoing Decommissioning

Abstract

Radiological characterisation of redundant nuclear facilities is a key stage towards being able to plan successfully for their safe and cost effective decommissioning. Cavendish Nuclear have developed a suite of techniques which can be applied to such facilities, including those which have high beta-gamma dose rates associated with them and for which personnel access can therefore be problematic. This paper focuses on the use of remote gamma ray detection technologies for mapping and quantifying the residual activity present in redundant nuclear facilities. The data from a series of radiological surveys is combined with laser mapping of the facility to generate a complete 3D model which contains both geometrical and radiometric information. Radiation transport modelling calculations are then performed to generate a complete understanding of the 3D gamma dose rate field in the facility. The combination of activity and dose rate information provides the decommissioning planning teams with the data that they need to best prioritise future work, allowing choices to be made on how to most effectively reduce dose rates in the facility, to keep operator dose rates as low as reasonably practicable, and to optimise waste disposal between the various waste categories.