초록 ▼

A nuclear reactor has a pressure vessel containing a core supported by the bed-plate. The bed-plate is arranged for admitting an upward flow of coolant into the core. The coolant, generally pressurized water, collects in an outlet plenum. The core comprises fuel assemblies each having a lower end pi

A nuclear reactor has a pressure vessel containing a core supported by the bed-plate. The bed-plate is arranged for admitting an upward flow of coolant into the core. The coolant, generally pressurized water, collects in an outlet plenum. The core comprises fuel assemblies each having a lower end piece. The bed-plate defines an inner volume containing coolant at a pressure lower than the coolant pressure under said bed-plate; the lower end piece of each of said fuel assemblies has a lower extension having a cross-sectional area smaller than the cross-sectional area of the fuel assembly above the bed-plate, cooperating with said bed-plate to define a passage for said flow of coolant into said core; and said extension is surrounded by an annular chamber communicating with said volume and defined by a downwardly facing external surface of said lower end piece.

대표청구항 ▼

A nuclear reactor having: a pressure vessel; a core within said pressure vessel; a bed plate supporting said core; an outlet plenum located above said core for receiving coolant which has circulated upwardly from under said bed-plate and through said core, said core comprising a plurality of upstand

A nuclear reactor having: a pressure vessel; a core within said pressure vessel; a bed plate supporting said core; an outlet plenum located above said core for receiving coolant which has circulated upwardly from under said bed-plate and through said core, said core comprising a plurality of upstanding sheathless fuel assemblies each having a bundle of fuel rods carried by a structure consisting of a lower end piece engaged into said bed-plate, an upper end piece, tie rods connecting said upper end piece and lower end piece and grids spaced apart along the tie rods; wherein: said bed-plate defines an inner volume containing coolant at a pressure lower than the coolant pressure under said bed plate. the lower end piece of each of said fuel assemblies has a downwardly directed extension having a cross-sectional area smaller than the cross-sectional area of the fuel assembly above the bed-plate; said bed-plate has a plurality of support means each for receiving and supporting one said lower end piece, each defining with a downwardly facing external surface of said lower end piece extension an annular chamber communicating with said volume and surrounding said extension; and said bed-plate and lower end piece are formed with aligned vertical passage means for straight unobstructed axial coolant flow without any angular deviation or bends from under said bed-plate into said fuel assembly and with leak means defining a coolant leak path having a first leg from a lower portion of said core to said annular chamber and a second leg from said passage to said annular chamber.