For over two decades all new nuclear safety related structures at nuclear power and nuclear chemical plant sites in the United Kingdom have been designed to resist the effects of internal and external hazards, including earthquakes. The ability of most of the earlier nuclear safety related structures to withstand internal and external hazards has also been assessed, so as to allow reasonably practicable improvements to be identified and implemented, and to demonstrate the risk to be tolerable. This paper describes HM Nuclear Installations Inspectorate’s (HMNII) approach to the assessment of safety submissions on earthquake resistance of nuclear structures. Andrew M Coatsworth, ACGI, DIC, MICE, CEng, CGeol Principal Inspector HM Nuclear Installations Inspectorate