Keywords: aircraft crashes, external events, nuclear power plants, NPP, plant siting, probabilistic risk assessment, PRA, risk zoning, seismic events, tornadoes, nuclear energy, nuclear safety, nuclear accidents, risk management, emergency management, emergency preparedness, safety-by-design, International Reactor Innovative and Secure, IRIS
Risk zoning in relation to risk of external events (application to IRIS design)
The design basis for any plant and site is closely related to the effects of any postulated external events and the limitation of the plant capability to cope with accidents, that is to perform safety functions. As a prime example of an advanced reactor and Nuclear Power Plant (NPP) with enhanced safety, the International Reactor Innovative and Secure (IRIS) has been considered in this work. In the used Safety-by-Design? approach, the Probabilistic Risk Assessment (PRA) plays obviously a key role, therefore a preliminary IRIS PRA has been developing along with the design. For the design and prelicencing process of IRIS, the external events analysis includes both qualitative evaluation and quantitative assessment. As a result of preliminary qualitative analyses, the external events that were chosen for more detailed quantitative scoping evaluation are high winds and tornadoes, aircraft crash and seismic events. In general, applying the quantitative assessment, bounding site characteristics can be used in order to minimise potential future restrictions on plant siting and risk zoning.