This TECDOC aims at illustrating the status in addressing safety and technological challenges encountered in the development, qualification and licensing of HBU nuclear fuels for Water Cooled Reactors (WCRs), summarizing the discussions held at a Technical Meeting organized by the IAEA in November 2022. This publication will provide useful insights for a future revision of IAEA Safety Standards Series No. SSG-52, Design of the Reactor Core for Nuclear Power Plants, as industry trends strongly signal a need to broaden the scope of this safety guide to include high burnup nuclear fuels. This publication is intended for Technical and Scientific Support Organizations (TSOs), regulatory organizations, operators, and research organizations.