Fuel bundle for boiling water nuclear reactors with at least one top filled water enclosed region overlying part length fuel rods

摘要

Part length water region(s) (R) is (are) located above part length fuel rods (18) in boiling water nuclear reactor fuel bundles (B). The part length water region(s) (R) include(s) discrete containers having entry ports (31) at the top of the part length water region(s) (R) for capturing water, and vent ports (41) for permitting internally generated steam to escape. The advantages of improved neutron moderation in the upper portion of the fuel assembly are maintained while the uranium fuel removal requirements are minimized.