In risk assessment, the second-order reliability method (SORM) and the conditional expectation Monte Carlo (CEMC) simulation were inter-related in order to analyse the safety of Brean and Newton revetments on the south and north coasts of the Inner Bristol Channel, South Wales, UK. In the CEMC simulation, storm surge and wave height were generated as correlated random variables with probability distributions describing the phenomena. Then, damage probability was predicted by approximating the limit state surface by a quadratic one having the identical curvature at the design point. It was found that revetment reliability was sensitive to tidal range, storm surge and wave data. Brean revetment was found to be safe, whereas maintenance works were required during the service life of Newton revetment. The model introduced a new technique into the reliability assessment of revetments subject to large tidal ranges and its predictions satisfactorily reflected the safety/damage conditions of the structures at the site.