Abstract: The present invention relates to a nuclear reactor core and fuel elements therefore. Stackable fuel elements, having the usual coolant holes machined therethrough, are formed with grooves along their vertical extent for alignment with similar grooves on adjacent fuel elements to define additional coolant passageways. These grooves provide coolant passageways between adjacent fuel elements enhancing the mechanical stability of the core. Furthermore, these additional coolant passageways allow a more efficient utilization of reactor core space and permit coolant escaping into the interstices between adjacent ends of blocks to be collected at these additional coolant passageways. Stability may be enhanced further by means of complementary elevations and depressions formed on end faces of the fuel blocks.

Abstract: A closed cycle gas turbine system is described employing a precooler for cooling the gas prior to compression. A closed loop coolant circuit for the precooler employs a heat exchanger. A storage tank is provided for storing a supply of coolant at a temperature substantially lower than the temperature of coolant in the coolant circuit at the discharge side of the heat exchanger. Means selectively circulate the coolant in the storage tank through the precooler to provide a power increase, when needed, in the gas turbine system.

Abstract: An insulation structure for a pressure vessel cavity is described in which a layer of fibrous insulation along the cavity wall is isolated from the remainder of the cavity to prevent circulation of fluid in the layer. Isolation is accomplished by means which define a gas flow space. Retaining means for the layer define a plurality of fluid passages communicating with the layer and allowing venting of the layer into the gas flow space upon depressurization of the cavity.

Abstract: A fuel element for a gas-cooled nuclear reactor having a housing surrounding a plurality of fuel pins through which coolant flows over the fuel pins. The housing has a portion of varying cross section and a plug disposed within the housing adjacent the portion. The plug and housing form a generally annular orifice through which the gas coolant flows, the size of which orifice is variable in accordance with the axial position of the plug, which can be varied from exterior of the reactor pressure vessel.