Design of a robust physical protection system for offshore floating nuclear power plants against ship-boarding threats: (1) Vital Area Identifications

Offshore Floating Nuclear Power Plants (OFNP) are anticipated to enhance nuclear safety based on lessons from the Fukushima Daiichi Nuclear Power Plant accident while promoting the peaceful use of nuclear energy through offshore installations. However, previous studies on OFNPs have primarily focused on the technical feasibility of plant concepts, emphasising nuclear safety, without addressing the new nuclear security challenges essential for social implementation in novel installation environments, such as offshore settings. This study establishes a methodology for identifying vital areas against ship-boarding threats and demonstrates its potential to enhance the robustness of OFNPs in terms of Physical Protection (PP). The ‘D-values’ concept is introduced to evaluate High Radiological Consequences (HRC) from direct sabotage and assess the impact of indirect sabotage by incorporating ‘Common Cause Failures’ (CCF) based on existing safety evaluations of ABWR. This newly developed Vital Area Identification (VAI) method provides a comprehensive approach applicable to OFNPs equipped with ABWRs and various offshore and land-based nuclear power plants with various reactor types.