The high burnup structure in nuclear fuel

Abstract

During its operating life in the core of a nuclear reactor, nuclear fuel is subjected to significant restructuring processes determined by neutron irradiation directly through nuclear reactions and indirectly through the thermo-mechanical conditions established as a consequence of such reactions. In today's light water reactors, starting after ~4 years of operation the cylindrical UO2 fuel pellet undergoes a transformation affecting its outermost radial region. The discovery of a newly forming structure required answering important questions concerning the safety of extended fuel operation, and still today poses a fascinating scientific challenge to fully understand the microstructural mechanisms responsible for its formation.