Which approach increases fuel utilization in nuclear reactors?

The approach that significantly increases fuel utilization in nuclear reactors is on-line refueling. This method allows for the gradual replacement of fuel assemblies while the reactor remains operational. By maintaining continuous operation, on-line refueling maximizes the use of nuclear fuel over time, enabling the reactor to generate electricity more consistently.

In contrast, periodic refueling typically involves shutting down the reactor for an extended duration to replace a substantial part of the fuel inventory. This downtime does not contribute to overall fuel utilization, as the reactor cannot generate power during this period. Shutting down for maintenance similarly disrupts operations, leading to lost opportunities for electricity production. While using enriched fuel can enhance the efficiency and output of a reactor, the actual process of on-line refueling directly improves the amount of fuel consumed relative to the power generated without interrupting reactor operation. Thus, on-line refueling stands out as a method that directly contributes to increased fuel utilization in the context of nuclear reactors.