BWR fuel assembly having oxide and hydride fuel

摘要

A boiling water nuclear reactor used for the production of electricity includes fuel rods and an assembly of these fuel rods that improve the reactor economics and safety. The fuel assemblies include hydride fuel pellets at selected axial and radial positions in addition to oxide fuel pellets. The hydride fuel functions simultaneously as a fuel and as a moderator. The hydride fuel can be made from different combinations of fissionable materials such as uranium, and hydrides such as zirconium hydride. The hydride fuel (such as U-ZrH.sub.1.6) is substituted for oxide fuel (UO.sub.2) in undermoderated regions of the core. Hydride fuel rods also replace water rods in the fuel assemblies. The use of hydrogen containing fuel rods and fuel assemblies enable flattening the power distribution across the core; reducing the need for power shaping with burnable poisons and control rods; improving the nuclear fuel utilization; increasing the reactor availability; increasing the safety factors for fuel meltdown accidents or, alternatively, increasing the power output from a given size core; reducing the cold shutdown reactivity margin; and reducing the leakage of neutrons from the core.