<DIV>The reactor pressure vessel (RPV) is central to a nuclear reactor. The main degradation mechanism affecting RPVs is irradiation embrittlement, where neutron bombardment from the nuclear reaction displaces atoms in the RPV steels. Inspection, testing, and appropriate maintenance are therefore required to ensure any damage is mitigated and to allow the plant to continue generating power. The editor, Naoki Soneda (CREIPI, Japan), with contributions from academics and industry practitioners, discusses RPV design, embrittlement processes in RPVs in different reactor types, and techniques for studying RPV embrittlement.</div>