Abstract: Irradiation target holders are configured to fit in open locations inside of an operating commercial nuclear core. Holders can be placed with ends at vertical bottom and top of the core or any position therebetween to directly expose holders to nuclear fuel reactions. Holders have ends and overall shape that can join with existing reactor structures, while fitting closely with fuel and moderator and being easily removable from the same. Holders are fabricated of any reactor-compatible material that will retain irradiation targets and daughter products. Holders securely retain irradiation targets and daughter products of any shape or phase throughout reactor operation. Holders can be installed during reactor outages and irradiated during operation without risk of movement or interference with operation. After a desired period of operation and irradiation, holders can be harvested from the core independent of other core structures and fuel.

Abstract: A nuclear reactor is operated with irradiation target holders fit in open locations inside of an operating commercial nuclear core and placed with ends at vertical bottom and top of the core or any position therebetween to directly expose holders to nuclear fuel reactions. Holders have ends and overall shape that are joined with existing reactor structures, while fitting closely with fuel and moderator and being easily removable from the same. Holders are fabricated of any reactor-compatible material that will retain irradiation targets and daughter products. Holders securely retain irradiation targets and daughter products of any shape or phase throughout reactor operation. Holders can be installed during reactor outages and irradiated during operation without risk of movement or interference with operation. After a desired period of operation and irradiation, holders can be harvested from the core independent of other core structures and fuel.

Abstract: Irradiation target holders are configured to fit in open locations inside of an operating commercial nuclear core. Holders can be placed with ends at vertical bottom and top of the core or any position therebetween to directly expose holders to nuclear fuel reactions. Holders have ends and overall shape that can join with existing reactor structures, while fitting closely with fuel and moderator and being easily removable from the same. Holders are fabricated of any reactor-compatible material that will retain irradiation targets and daughter products. Holders securely retain irradiation targets and daughter products of any shape or phase throughout reactor operation. Holders can be installed during reactor outages and irradiated during operation without risk of movement or interference with operation. After a desired period of operation and irradiation, holders can be harvested from the core independent of other core structures and fuel.

Abstract: A reactor fuel bundle includes both full-length fuel rods and part-length fuel rods. The part-length rods are clumped in two groups—a first rod group surrounds one or more water passages which are generally centrally disposed in a channel of the fuel bundle, and a second rod group is distributed about an inner perimeter wall of the channel.

Abstract: A nuclear fuel bundle has differential peak power limits for the edge or peripheral fuel rods and the interior fuel rods. Also, the magnitude of nuclear fuel in the edge or peripheral rods is decreased in comparison with the magnitude of nuclear fuel in the interior rods. The nuclear reactor can thus operate at higher power output by decreasing the margins between the power outputs and peak power limit of the interior rods, as well as by decreasing the margins between the power outputs of the edge or peripheral rods and the increased peak power limit of those rods. The outer or peripheral edge rods can also be enriched for enhanced power output.

Abstract: A nuclear fuel bundle includes a square array of fuel rods each having a concentration of enriched uranium and plutonium. Each rod of an interior array of the rods also has a concentration of gadolinium. The interior array of rods is surrounded by an exterior array of rods void of gadolinium. By this design, usage of plutonium in the nuclear reactor is enhanced.