For some time small high-temperature reactors, because of their special safety properties, have been of interest to various countries. The prototype of these facilities is the Arbeitsgemeinschaft Versuchsreaktor in Jülich. During the past 17 years of operation, the components of the reactor, especially the fuel elements, have proved suitable for achieving permanent temperatures of the heat transfer medium of up to 950 °C with low contamination of the loop. The convincing safety behavior of the reactor has been demonstrated. It is apparent that for this design an after heat removal system is not required, since the afterheat can be adequately removed by heat conduction. In addition to the thorium/uranium fuel cycle originally planned, utilization of low-enrichment uranium in the fuel elements has also been fully developed.