Nuclear fuel assemblies include at least one fluence control structure for use in a nuclear reactor core with other nuclear fuel assemblies. Such flux-limiting assemblies and structures may be positioned outside of or around the other nuclear fuel assemblies in the core so as to reduce neutron flux beyond the fluence controlled nuclear fuel assemblies, and fluence control structures may be positioned at an outside edge of the core. Fluence control structures limit neutron flux with non-fuel materials in structures like fuel rods and inserts, channels, shield curtains, etc. at particular positions in fuel assemblies. An engineer may select and/or install fluence-limiting fuel assemblies with flux-limiting characteristics in cores having neutronics profiles expected to benefit from such flux limitation.