Which fuel is most commonly used in light-water nuclear reactors?

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Labeled diagram showing the process of a nuclear power plant with a pressurized-water reactor. Water circulates through the reactor core, heats to produce steam in a steam generator, which drives a turbine connected to an electric generator. Steam is then cooled in a condenser using water from a cooling tower, which releases nonradioactive water vapor. Control rods, pumps, and transmission lines are also indicated. — nuclear power Schematic diagram of a nuclear power plant using a pressurized-water reactor.

The fuel most commonly used in light-water nuclear reactors (LWRs) consists of pellets of sintered uranium dioxide.21

To prepare this fuel, the uranium is typically enriched to 3 to 5 percent uranium-235. This enrichment is necessary because light water, which serves as both the coolant and the moderator in these reactors, tends to absorb more neutrons than other types of moderators. The ceramic uranium dioxide pellets are loaded into cladding tubes made of zirconium alloy, which are then bundled together to form a fuel assembly.12