A new approach to preparing safety cases for existing nuclear plant (COSR)

BNFL is committed to achieving world class safety performance, through a pr ocess of continuously reviewing and improving its safety practices. In the mid 1990s, as part of this process, the company began to develop a new type of safety case, for existing non-reactor nuclear plants, called the contin ued operation safety report (COSR). Following a significant amount of devel opment work from experts within BNFL and important contributions from its r egulators, the first approved COSR was recently completed and submitted to the Nuclear Installations Inspectorate. The COSR aims to provide a visibly integrated safety and engineering case for the adequacy of continued operat ion of a nuclear facility. it achieves this by identifying the main plant s tructures, systems and components that have a safety function and provides the appropriate supporting engineering substantiation. The COSR aims to exp lore plant safety and identify worthwhile improvements. The document also a ims to be reader-friendly by focusing on the main safety issues. It is ther efore a slim safety summary which provides operators, safety specialists an d regulators with an overview and introduction into the broader, more detai led safety case. This paper provides an overview of the COSR and its produc tion process, describing the safety case improvements that have been made b y comparing it to its predecessor, the fully developed safety case. The pap er also illustrates the benefits of the COSR by providing current examples of its application on existing BNFL plant. Finally, the paper describes ong oing development work aimed at further improving the COSR and its productio n process.