Articles on the technical foundations of nuclear safety: defence in depth, safety functions, protection and support systems, the management of design-basis and severe accidents, and decay heat removal. The focus is on physical processes, engineering solutions and verifiable evidence through which a plant prevents event progression, limits its consequences and reaches a safe state.
In the original RBMK design, initial insertion of fully withdrawn control and safety rods could introduce positive reactivity locally. Drawing on INSAG-7, this article examines the physics of positive SCRAM, its relationship to void reactivity, and the design changes after Chernobyl, focusing on the reliability of the shutdown function.
Successful leak testing is not the only evidence that a containment system will retain its function under demanding conditions. The publicly documented example of Krško Nuclear Power Plant shows how structural integrity and leak tightness are verified through inspections, local tests, corrective actions and traceable records.
Steam condensation in containment helps reduce pressure, but it does not remove hydrogen. The hydrogen fraction in the gas mixture may even increase. Part 4 of the series explains hydrogen generation, spatial distribution and the different ways in which the hazard is managed.
During a LOCA, the containment system receives mass and energy released from the damaged reactor coolant system. This article follows the initial pressure response, condensation, water collection, recirculation and long-term heat removal across different containment designs.
