Reactors cooled by high temperature gas can be used as high converters, thermal breeders or fast breeders, depending upon fuel and reactor configuration. This paper discusses the status of the current HTGR programs in the United States. The technological relationships of HTGR and fast gas-cooled reactors (FGCR) will be discussed.

The HTGR is a high-temperature system with reactor outlet coolant gas temperature in the range of 1400°F, permitting the generation of 1000°F steam and higher as required by the needs of modern hightemperature steam turbine generators. Because of the minimum wastage of excess neutrons high conversion ratios of thorium (fertile material) to fissionable U233 can be obtained.


Suivant le type de combustible et leur configuration, les réacteurs à haute température refroidis au gaz peuvent être utilisés comme bons convertisseurs, ou comme breeders thermiques ou rapides. Le présent exposé discute l'état actuel d'avancement des programmes de réacteurs HTGR aux Etats-Unis. Les rapports technologiques entre ces réacteurs HTGR et les réacteurs rapides refroidis au gaz (FGCR) seront également exposés.

Le réacteur HTGR est un système à haute température avec une température de gaz à la sortie de l'ordre de 760°C, ce qui permet de produire de la vapeur à 540°C et même au-dessus; ces conditions sont celles des turbines à vapeur dans les centrales modernes. Du fait d'une très bonne économie des neutrons, dans le réacteur, on obtient de forts taux de conversion de matériaux fertiles (thorium) en matériaux fissiles (U233).


With the development of nuclear power, a new energy source became available to supplement our traditional sources of energy from fossil fuels.

Nuclear power has several unique characteristics, and a brief consideration of these characteristics will help us to place it in proper perspective with relation to the total power picture. The following remarks will pertain specifically to power reactors and will exclude such applications of nuclear power as isotopic power sources which, although very valuable in providing an unattended, long life source of power for such items as harbor buoys, small weather stations, etc., will in the aggregate represent a very small portion of the total power picture. Fission power reactors, for the purpose of generating electrical energy, are relatively insensitive to location. For example, it is possible to select a reactor site near the point at which one has a large energy demand without necessarily incurring a fuel transportation penalty. Thus, with nuclear generating stations, one is not particularly concerned with the by F. DE HOFFMANN, General AtomiclGeneral Dynamics Corporation, U.S.A. economic desirability of locating a power plant near the source of fuel simply because the volume of fuel required for a nuclear unit is negligible compared to the energy equivalent volu

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