Thermal Hydraulic Analysis and Modeling of the HTTR Using the RELAP5-3D

A thermal hydraulic model for the HTTR (High Temperature Engineering Test Reactor) has been developed using the RELAP5-3D code. The HTTR is a high temperature gas-cooled reactor (HTGR) developed, designed, constructed, and operated by the Japan Atomic Energy Research Institute (JAERI). It is a helium-cooled and graphite-moderated with a thermal power of 30 MW. In this work, a HTTR core inlet and outlet coolant temperatures, mass flow rate, pressure drop and heat structures (fuel and graphite block) temperatures have been reproduced using a RELAP5 model. The simulation was done in the high temperature operation mode (950°C) and in the rated operation mode (850 °C). The results have been compared with the available data. The calculations were performed using the point kinetic model. It is demonstrated that the developed model in the RELAP5-3D is capable of reproduce the thermal behavior of the reactor in steady state operation.