Reactor Pressure Vessel (RPV) meaning

In a nuclear power plant (NPP), the reactor pressure vessel (RPV) is the thick‑walled steel vessel that contains the reactor core and primary coolant at high pressure, forming the primary pressure boundary. It is safety‑critical and central to nuclear site licensing, safety cases and decommissioning. Not generally defined in UK or Irish statute or case law, RPV is an engineering term used across contracts, technical specifications, nuclear site licences and regulatory guidance. In Great Britain, the RPV is controlled through the Nuclear Installations Act 1965 licensing regime and oversight by the Office for Nuclear Regulation (ONR), with requirements on structural integrity and ageing management (embrittlement surveillance, in‑service inspection, periodic safety review). It is typically built to recognised codes (e.g., ASME Section III/RCC‑M) and subject to licence conditions such as LC 14, LC 23 and LC 28. Northern Ireland has no civil NPPs; usage is mainly descriptive and in transboundary or emergency planning, with pressure equipment law aligned to GB. In Ireland there are no NPPs; the term arises in regulatory and planning materials on nuclear safety and transboundary environmental assessment. Usage is otherwise consistent across the jurisdictions.