Published in:Jülich : Kernforschungsanlage Jülich, Verlag, Berichte der Kernforschungsanlage Jülich 1413, 36 p. (1977).
Language:
German
Origination:
Footnote:
Diese Datenquelle enthält auch Bestandsnachweise, die nicht zu einem Volltext führen.
Description:
The pebble-bed, high temperature reactor (HTR) has. now been developed to the stage where steam-cycle plants having core outlet gas temperatures of 750 °C are being built. This reactor system is also ideally suited for operation at higher temperatures, and is a potential source of process heat for endothermic chemical processes, such as coal gasification and methane reforming, which require temperatures of up to 950 - 1000 °C. However, before this potential can be realised, considerable investigation and development of the materials for the reactor core and the primary gas circuit is still required. Concerning the core components, the current state-of-the-art and the objectives of the development work on the spherical fuel elements, coated particles and structural graphite are discussed. The combined requirements of higher gas exit temperature and lower-fission product release mean that the properties of the coated particles are important. As an example of the structural graphite, the non-replaceable reflector of the process heat reactor is discussed. The primary circuit will be constructed mainly from metallic materials, although, some ceramics are also being considered. Components of interest are hot gas ducts, liners, methane reformer tubes and helium-helium intermediate heat exchangers. The gaseous impurities present in the helium coolant may cause oxidation and carburization of the nickel-base and iron-base alloys envisaged for use in these components, with a possible associated adverse effect on the mechanical properties such as creep and atigue. Test capacity has therefore been installed to investigate materials behaviour in simulated reactor helium under both constant and alternating stress conditions. The first results on the creep behaviour of several alloys in impure helium are presented and discussed.