STUDY OF AVAILABLE MARGINS OF CONTAINMENTS AGAINST STRUCTURAL FAILURE

The structural designs of nuclear power stations all over the world ha ve been carried out using a variety of codes of practice with hardly a ny uniformity. This may have given rise to primary containment structu res with varying degrees of margin against failure. It is fruitless to argue about the appropriateness of various provisions in codes of pra ctice for design and analyses formulated by different committees in di fferent countries. In this paper a method to find the available margin against collapse is defined without making any reference to the codes of practice used in the original design of the containment structure. A structured step-by-step method is suggested which can be universall y applied irrespective of the location, condition, age or type of prim ary containment. The three key factors in a containment structure are the geometry, the material properties and the loading. Coupled with th ese there are two further aspects namely, the condition of the structu re and the efficiency of the analytical method. Objective judgement of the elements influencing these factors is suggested in the method of finding the available margin. The whole process is based on the broad philosophy of assessment of existing structures where the geometric an d material variabilities assumed at the design stage have been conside rably narrowed down and most of the analytical conservatisms removed b y the application of state-of-the-art computer software and parametric studies.