Significance of the helium turbine power plant at Oberhausen (EVO) and of the high-temperature helium test facility at Juelich (HHV) for the development of the HTR direct-cycle system (HHT)

Since 1972, developmental work sponsored by the Federal Republic of Germany and Switzerland has been carried out for the construction of a high-temperature reactor with a helium turbine (HHT). The first HHT plant is designed for an electric power rating of 1080MW. To reduce the risks of the first HHT system and to prove its marketability, it is necessary to subject its most important components to largely original operating conditions. For experimental studies, several minor experimental units are already available within the scope of the HHT project. The Oberhausen helium turbine power plant (EVO) and the Juelich high-temperature test facility (HHV) are intended to serve as large-scale pilot plants for the HHT project. These systems will enable conclusive studies on loop elements for the first HHT system under maximum proximity to real scale and operating conditions. The two systems are being commissioned and under construction, respectively. In designing this first helium-turbine plant, two requirements were to be met. On the one hand, it was to generate electricity and heat for district heating and on the other hand the know-how gained in building and primarily the experience obtainable in running the plant should be transferable to the project high-temperature reactor with a helium turbine in a closed cycle. The thermoelectric power plant fired with fossil fuels and provided with a gas turbine has been designed for an electrical rating of 50MW and a heating output of 53.5MW, for the first time using helium as a working medium. The operating data (primary pressure 27 bar, primary temperature 7500C) have been selected such that the dimensions and load conditions of the main components come close to those of a first HHT system. In this system, the behaviour of the turbo-unit, the heat exchanger with piping and auxiliary facilities are being investigated in connection with all operating flows such as startup, shutdown, load changes, load discharge, etc. For this purpose, the system has been provided with comprehensive measurement instrumentation