Patent Number: 
Section: claims

1. A supercritical-pressure water cooled reactor comprising: a reactor vessel including: first and second end parts dimensioned to contain supercritical-pressure coolant and a shell part disposed between the first and the second end parts dimensioned to contain sub-critical-pressure coolant;  first and second core-support plates each having a plurality of through-holes, the first and the second core-support plates being disposed in and fixed to the reactor vessel so that the core-support plates divide space inside the reactor vessel into first and second supercritical-pressure portions in the first and the second end parts, respectively, and a sub-critical pressure portion in the shell part;  a plurality of fuel tubes each having an interior volume, an outer surface and first and second open ends fixed to one of the through-holes in the first core-support plate and one of the through-holes in the second core-support plate, respectively, so that the interior volumes of the fuel tubes are in fluidic communication with the supercritical-pressure portions, the outer surfaces of the fuel tubes can be exposed to the sub-critical pressure coolant, and the supercritical-pressure coolant and the sub-critical pressure coolant cannot be mixed together in the reactor vessel;  a plurality of nuclear fuel assemblies disposed in the fuel tubes;  a supercritical-pressure water inlet disposed in the reactor vessel for introducing supercritical-pressure water into one of the supercritical-pressure portions;  a supercritical-pressure steam outlet disposed in the reactor vessel for extracting supercritical-pressure steam generated in the fuel tubes out of one of the supercritical-pressure portions;  a sub-critical pressure coolant inlet disposed in the reactor vessel for introducing sub-critical pressure coolant into the sub-critical pressure portion;  a sub-critical pressure coolant outlet disposed in the reactor vessel for extracting sub-critical pressure coolant out of the sub-critical pressure portion;  a plurality of control rods which are arranged so that the control rods can be inserted into the sub-critical pressure portion adjacent to the fuel tubes through the shell part; and  a control rod drive for driving the control rods from outside of the reactor vessel. 2. A supercritical-pressure water cooled reactor according to  claim 1 , wherein the supercritical-pressure water inlet and the supercritical-pressure steam outlet are disposed in the first and the second end parts, respectively. claim 1 3. A supercritical-pressure water cooled reactor according to  claim 1 , wherein: claim 1 the reactor vessel is arranged so that an axis of the shell part lies horizontally; and  the control rods are arranged substantially vertically. 4. A supercritical-pressure water cooled reactor according to  claim 1 , wherein: claim 1 the open ends of the fuel tubes penetrate and are fixed to the through-holes with adapters inserted between the fuel tubes and the through-holes. 5. A supercritical-pressure water cooled reactor according to  claim 1 , further comprising: claim 1 a dividing plate for dividing the first supercritical-pressure portion into inlet and outlet chambers;  wherein the first core-support plate has inlet and outlet portions facing the inlet and the outlet chambers, respectively, wherein some of the through-holes are disposed in the inlet portion and the rest of the through-holes are disposed in the outlet portion; and  wherein the supercritical-pressure water inlet and the supercritical-pressure steam outlet are disposed in the inlet and the outlet chambers, respectively. 6. A supercritical-pressure water cooled reactor comprising: a reactor vessel including a shell part having two ends with an inlet header on one end and an outlet header on the other end;  first and second core-support plates each having a plurality of through-holes, the first core-support plate being fixed to the inlet header, the second core-support plate being fixed to the outlet header, so that an inlet header portion for containing supercritical-pressure coolant, an outlet header portion for containing supercritical-pressure coolant and a shell portion between them for containing sub-critical-pressure coolant are formed in the reactor vessel;  a plurality of fuel tubes each having an outer surface and first and second open ends fixed to one of the through-holes of the first and the second core-support plates, respectively, for forming sealed passages of the supercritical-pressure coolant from the inlet header portion to the outlet header portion via the fuel tubes so that the supercritical-pressure coolant and the sub-critical pressure coolant cannot be mixed together in the reactor vessel, wherein the outer surfaces of the fuel tubes are exposed to the sub-critical pressure coolant;  a plurality of nuclear fuel assemblies disposed in the fuel tubes;  a feed water inlet disposed in the reactor vessel for introducing supercritical-pressure water into the inlet header portion;  a main steam outlet disposed in the reactor vessel for extracting supercritical-pressure steam out of the outlet header portion;  a coolant inlet disposed in the reactor vessel for introducing sub-critical pressure coolant into the shell portion outside of the fuel tubes;  a coolant outlet disposed in the reactor vessel for extracting sub-critical pressure coolant out of the shell portion outside of the fuel tubes;  a plurality of control rod guide tubes inserted into the shell portion outside of the fuel tubes;  a plurality of control rods which are arranged so that the control rods can be inserted into the control rod guide tubes; and  a control rod drive for driving the control rods from outside of the reactor vessel. 7. A supercritical-pressure water cooled reactor comprising: a reactor vessel having a first end and a second end and including a shell part with an inlet-outlet header on the first end and an intermediate header on the second end;  first and second core-support plates each having a plurality of through-holes, the first and the second core-support plates being fixed to the inlet-outlet header and the intermediate header, respectively, so that an inlet-outlet header portion, an intermediate header portion and a shell portion between them are formed in the reactor vessel;  a dividing plate for dividing the inlet-outlet header portion into inlet and outlet chambers, so that the first core-support plate is divided into inlet and outlet portions each having a plurality of the through-holes;  a first group of fuel tubes, each having first and second open ends, the first open end being fixed to one of the through-holes of the inlet portion of the first core-support plate, and the second open end being fixed to one of the through-holes of the second core-support plate for forming sealed passages of the supercritical-pressure coolant from the inlet chamber to the intermediate header portion;  a second group of fuel tubes, each having third and fourth open ends, the third open end being fixed to one of the through-holes of the second core-support plate, and the fourth open end being fixed to one of the through-holes of the outlet portion of the first core-support plate for forming sealed passages of the supercritical-pressure coolant from the intermediate header portion to the outlet chamber, wherein the supercritical-pressure coolant and the sub-critical pressure coolant cannot be mixed together in the reactor vessel, and outer surfaces of the fuel tubes are exposed to the sub-critical pressure coolant;  a plurality of nuclear fuel assemblies disposed in the fuel tubes;  a feed water inlet disposed in the reactor vessel for introducing supercritical-pressure water into the inlet chamber;  a main steam outlet disposed in the reactor vessel for extracting supercritical-pressure steam out of the outlet chamber;  a coolant inlet disposed in the reactor vessel for introducing sub-critical pressure coolant into the shell portion outside of the fuel tubes;  a coolant outlet disposed in the reactor vessel for extracting sub-critical pressure coolant out of the shell portion outside of the fuel tubes;  a plurality of control rod guide tubes inserted into the shell portion outside of the fuel tubes;  a plurality of control rods which are arranged so that the control rods can be inserted into the control rod guide tubes; and  a control rod drive for driving the control rods from outside of the reactor vessel. 8. A supercritical-pressure water cooled reactor comprising: a reactor vessel including a shell part with an inlet-outlet header on an end;  a core-support plate with a plurality of through-holes fixed to the inlet-outlet header, so that an inlet-outlet header portion and a shell portion are formed in the reactor vessel;  a dividing plate for dividing the inlet-outlet header portion into inlet and outlet chambers so that the core-support plate is divided into inlet and outlet portions each having a fraction of the plurality of through-holes;  a plurality of curved fuel tubes, each having first and second open ends fixed to one of the through-holes of the inlet and outlet portions of the core-support plate, respectively, for forming sealed passages of the supercritical-pressure coolant from the inlet chamber to the outlet chamber via the fuel tubes, wherein the supercritical-pressure coolant and the sub-critical pressure coolant cannot be mixed together in the reactor vessel, and outer surfaces of the fuel tubes are exposed to the sub-critical pressure coolant;  a plurality of nuclear fuel assemblies disposed in the fuel tubes;  a feed water inlet disposed in the reactor vessel for introducing supercritical-pressure water into the inlet chamber;  a main steam outlet disposed in the reactor vessel for extracting supercritical-pressure steam out of the outlet chamber;  a coolant inlet disposed in the reactor vessel for introducing sub-critical pressure coolant into the shell portion outside of the fuel tubes;  a coolant outlet disposed in the reactor vessel for extracting sub-critical pressure coolant out of the shell portion outside of the fuel tubes;  a plurality of control rod guide tubes inserted into the shell portion outside of the fuel tubes;  a plurality of control rods which are arranged so that the control rods can be inserted into the control rod guide tubes; and  a control rod drive for driving the control rods from outside of the reactor vessel. 9. An electric power generation plant having: (a) a supercritical-pressure water cooled reactor comprising:  a reactor vessel including: first and second end parts for containing supercritical-pressure coolant and a shell part disposed between the first and the second end parts for containing sub-critical pressure coolant which is separated from the supercritical-pressure coolant in the reactor vessel;  first and second core-support plates each having a plurality of through-holes, the first and the second core-support plates being disposed in and fixed to the reactor vessel so that the core-support plates divide space inside the reactor vessel into first and second supercritical-pressure portions in the first and the second end parts, respectively, and a sub-critical pressure portion in the shell part;  a plurality of fuel tubes each having an inner volume, an outer surface, and first and second open ends fixed to one of the through-holes in the first core-support plate and one of the through-holes in the second core-support plate, respectively, so that the inner volumes of the fuel tubes are in fluidic communication with the supercritical-pressure portions, the outer surfaces of the fuel tubes can be exposed to the sub-critical pressure coolant, and the supercritical-pressure coolant and the sub-critical pressure coolant cannot be mixed together in the reactor vessel;  a plurality of nuclear fuel assemblies disposed in the fuel tubes;  a supercritical-pressure water inlet disposed in the reactor vessel for introducing supercritical-pressure water into one of the supercritical-pressure portions;  a supercritical-pressure steam outlet disposed in the reactor vessel for extracting supercritical-pressure steam generated in the fuel tubes out of one of the supercritical-pressure portions;  a sub-critical pressure coolant inlet disposed in the reactor vessel for introducing sub-critical pressure coolant into the sub-critical pressure portion;  a sub-critical pressure coolant outlet disposed in the reactor vessel for extracting sub-critical pressure coolant out of the sub-critical pressure portion;  a plurality of control rods which are arranged so that the control rods can be inserted into the sub-critical pressure portion adjacent to the fuel tubes through the shell part; and  a control rod drive for driving the control rods from outside of the reactor vessel;  (b) a higher pressure turbine receiving the supercritical-pressure steam extracted from the supercritical-pressure portion of the reactor;  (c) means for extracting part of output steam of the higher pressure turbine to introduce the output steam to the sub-critical pressure portion of the reactor;  (d) a lower pressure turbine receiving the sub-critical pressure coolant extracted from the sub-critical pressure portion of the reactor; and  (e) an electric generator driven by at least one of the higher and lower pressure turbines. 10. A supercritical-pressure water cooled reactor according to  claim 8 , wherein: claim 8 the reactor vessel is arranged so that an axis of the shell part lies substantially horizontally; and  the control rod guide tubes are arranged substantially vertically.