A SHORT HISTORY OF CRITICALITY SAFETY IN THE UNITED-KINGDOM

The objective of this paper is to outline the evolution of the specialist field of criticality safety. The generation of basic data and the compilation of handbooks is described, together with an indication of the problems inherent in designing the first facilities whilst this data was being gathered. An overview of the development of the computer code MONK and its predecessor GEM is given in the historical context of the growth of the UK nuclear industry. The procedures and systems under which criticality safety assessments have been produced and how these have evolved into current practice is also reviewed. Probabilistic risk analysis and its current use at Sellafield is touched upon. Finally, an attempt is made to identify the challenges which lie in the years ahead.