Status report on intergrated analysis methods for nuclear reactor structural analysis

Abstract

The purpose of this paper is to look at the analysis of a nuclear reactor system as a total analysis task and to examine the assumptions which are made in the separation of the analysis task into its component disciplines. The structural analysis discipline is then examined in more detail to try to define a workable approach to an integrated structural analysis of the reactor system. We will start with a general discussion of the total analysis task, starting from the initial concept of the reactor plant. The total task will then be subdivided into the respective disciplines and an attempt will be made to rationalize or criticize the division into separate disciplines. The discipline of structural mechanics will then be examined in view of its interactions with other disciplines such as fluid flow and nuclear analysis to determine the degree of coupling which exists among these disciplines. This will be done by examining the interactions of the state variables which apply at each point of the system. The state variables considered will include fluence, temperature, displacement and pressure. The state variables defined will then be used as the basis for the definition of an overall structural model of the reactor system. Such an overall model can be conceived in terms of the present status of analytical techniques, by the use of such concepts as substructuring, constraint equations, coupled solutions for heat transfer, stress and dynamic analysis, along with fourth generation computer capabilities. A block design for an overall structural model will be discussed and also the areas which require new analysis techniques. The last section will present an outline of a mode of operation of a structural design/analysis activity which is established to implement a comprehensive integrated structural analysis of an entire reactor system. The concept of an evolving model of the system will be presented and the coordination required to successfully manage such a design/analysis approach will be discussed. A brief discussion of the effects of non-linear effects such as creep, plasticity, gaps on the overall approach will be included.