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: In combination with a boiling water nuclear reactor core undergoing a reload, an improved core reload and process of reloading is disclosed. The core reload consists of fuel bundles having differing design margins to critical power and linear heat generation rate. Specifically, a first part of the core reload is selected from fuel bundles having relatively high critical power margin and relatively lower linear heat generation margin. A second part of the core reload is selected from fuel bundles having relatively high linear heat generation margin and relatively low critical power margin. Distribution of the reload fuel bundles throughout the reactor core occurs as a function of critical power margin and linear heat generation rate margin. Specifically, fuel bundles having the high critical power margin are placed in selected intervals to the central portion of the cylindrical core. Fuel bundles having high linear heat generation margin are placed in the peripheral region of the core.