Leakage flow characteristics of seal mechanism for HTGR core support blocks.

Abstract

In a high temperature gas-cooled reactor core consisting of prismatic blocks, leakage flows of the coolant gas occur at the gaps between blocks. Since the leakage flows reduce the effective flow rate in coolant channels, it is important to regulate the coolant flows in a reactor core. In particular, it is necessary to seal the gap between the core support blocks. The seal mechanism, in which the graphite seal elements are installed to cover the gaps between core support blocks, has been devised in the design of the very high temperature gas-cooled reactor. It is estimated that the nonuniform deformation of the core Support structure due to the temperature gradient leads to the creation of the level difference between core support blocks and thus to the malfunction of the seal mechanism. Here, air flow experiments using the models of the core support blocks have been carried out to study the leakage flow characteristics of this seal mechanism under various configurations of the blocks and the seal elements. The pressure loss coefficient factors have been evaluated from the experiments.