Fault Analysis of a Gas Turbine HTGR

The Gas Turbine High Temperature Gas-Cooled Reactor combines a helium-cooled reactor core of established design with a closed-cycle helium turbine power-conversion system. This paper discusses the design considerations which mitigate the consequences of failure of the rotating machinery located within the reactor vessel. The methods of analysis and summary of results are presented for the failure modes of most concern. The spectrum of potential incidents which have been evaluated include turbine blade, rim, and disk failures. The requirements and design methods for rotor containment are discussed. The turbomachine maintains a pressure ratio of about two between the high and low pressure portions of the loop; postulated failures can, therefore, lead to rapid rates of pressure change. The preliminary evaluation of this internal pressure equilibration is presented.