SIMULATION OF NUCLEAR-PHYSICAL PROCESSES IN THE SURFACE LAYER OF A FUEL KERNEL WITH A CONSUMABLE ABSORBER

The structure, density, and chemical and phase state of nuclear fuel change considerably with deep burnup. In the present work, the neutron-physical processes in the peripheral layer of a fuel kernel with a consumable absorber are simulated. It is shown that plutonium will actively accumulate in a 50-200 μm thick surface layer. The burnup depth in this layer will be much greater than the average value over the fuel assemblies. A combined fuel element with an absorber where the central part has the usual enrichment (4-5% 235 U) and does not contain consumable absorbers and the peripheral layer consists completely of the consumable element is proposed to decrease the influence of consumable absorbers on fuel properties.