Leakage Flow Characteristics of Highly Effective Graphite Seal Mechanism for HTGR Core Support Blocks

Abstract

The prevention of leakage flows of coolant gas is important for a thermal hydraulic design of HTGR core which consists of prismatic graphite blocks. In particular, a seal mechanism for the core support blocks is necessary because gaps between core support blocks induce leakage flows in the core. Here, a seal mechanism, which consists of graphite seal element with triangular cross section and V-shaped seal seat, has been proposed. Air flow experiments were conducted to study the leakage flow characteristics of this seal mechanism. It is shown that the present seal mechanism is highly effective in preventing leakage flows as compared with the plate-type seal mechanism. It is also found that most of the leakage flow occurs at the seal element end-gaps and the pressure loss coefficient factor of this seal mechanism can be predicted with the use of the effective flow area of the end-gaps.