Thermal transient analysis for structural integrity of high temperature components in HTTR

The High Temperature Engineering Test Reactor (HTTR) is the first reactor of graphite-moderated and helium gas-cooled type in Japan and it generates thermal energy at a very high temperature of 950degC at the reactor outlet. Since experience is very limited in evaluating the structural integrity for such a high temperature reactor, a reliable method is required to be established for analyzing transient responses of the reactor, particularly its thermal transient response. Such a method should provide criteria for classifying transient events into some loading categories, selecting representative transient events for each loading category and establishing analytical conditions and an analytical model for the events and also an analytical tool. This paper presents a method for analyzing thermal transient response of the HTTR reactor cooling system for representative events which are required for the structural integrity evaluation and also their analytical results. The analytical results could demonstrate unique features of the HTTR and its highly inherent safety. (author)