Abstract: A control strategy for a pressurized water nuclear reactor that employs separate, independent control rod banks for respectively controlling Tavg and axial offset within corresponding deadbands. The strategy does not permit the control banks controlling reactor core power and the control banks controlling axial offset to move together, but normally gives preference to the control banks controlling the Tavg except when a demand signal is received simultaneously by both independent control rod banks to move in a same direction, in which case, the control bank compensating for the axial offset is given preference.

Abstract: The present invention provides novel fuel assemblies for use with PWR nuclear reactors and power plants, and in particular, VVER nuclear reactors. The fuel assemblies offer enhanced structural stability, skeletal rigidity, and distortion (bow and twist) resistance to support high burn-up fuel management. Each fuel assembly may include a plurality of fuel rods, a plurality of control rods and guide thimbles, at least one instrumentation tube, and a plurality of grids. At least one fuel rod is replaced with a structural support replacement rod made from zirconium (Zr) alloy, stainless steel, or any other suitable material. The structural support replacement rod may be hollow or solid. The structural support replacement rods are preferably disposed at or about the periphery, and in some cases, the corners of the geometric array, which is preferably a hexagon or square.

Abstract: An advanced gray rod control assembly (GRCA) for a nuclear reactor. The GRCA provides controlled insertion of gray rod assemblies into the reactor, thereby controlling the rate of power produced by the reactor and providing reactivity control at full power. Each gray rod assembly includes an elongated tubular member, a primary neutron-absorber disposed within the tubular member said neutron-absorber comprising an absorber material, preferably tungsten, having a 2200 m/s neutron absorption microscopic capture cross-section of from 10 to 30 barns. An internal support tube can be positioned between the primary absorber and the tubular member as a secondary absorber to enhance neutron absorption, absorber depletion, assembly weight, and assembly heat transfer characteristics.

Abstract: A control strategy for a pressurized water nuclear reactor that employs separate, independent control rod banks for respectively controlling Tavg and axial offset within corresponding deadbands. The strategy does not permit the control banks controlling reactor core power and the control banks controlling axial offset to move together, but normally gives preference to the control banks controlling the Tavg except when a demand signal is received simultaneously by both independent control rod banks to move in a same direction, in which case, the control bank compensating for the axial offset is given preference.