Safety margins determination for design basis-exceeding external hazards Further safety assessments of the severe accidents scenarios including external hazards such as floods, earthquakes, fires etc.Building improved knowledge of nuclear plant behaviour by updated probabilistic safety assessments (PSA) along those scenarios.Improvement of tools such as safety monitors for training purposes especially in the field of human factors under accident conditions.Update of severe accident management guidelines (SAMG) for mitigation of NPP hypothetical accidents consequences International cooperation in this area is promoted in order to provide additional value. The involvement of entities from third countries is of high importance and their participation is strongly encouraged.At least 5% of the total action budget must be dedicated to Education and Training activities for Ph.D. students, postdoctoral researchers and trainees supported through the action (see Conditions for the Call- Eligibility and admissibility conditions).The Commission considers that proposals requesting a contribution from the Euratom Programme up to EUR 4.0 million would allow this specific challenge to be addressed appropriately. Nonetheless, this does not preclude submission and selection of proposals requesting other amounts. EU nuclear plants need to demonstrate compliance with evolving and stringent safety requirements. These research actions need to result in updated knowledge on severe accidents phenomena including external hazards and to provide reliable calculation results. Therefore, they should support upgrades of simulation tools and their experimental validation to improve safety features and accident management strategies for GEN II, GEN III and GEN III+ reactors. Research actions would also identify best practices, improved assessment methods and recommendations for NPP safety upgrades where relevant. Increased knowledge and understanding of severe accidents transients as well as update of simulation tools and PSA methods for the reduction of consequences for accidents with very low probability and external hazards. The results and recommendations for improving emergency response will be reflected and integrated into SAMG. The actions would result in reinforcement of severe accident management strategies for the Generation II and III nuclear reactors as well as it could support compliance with the amended Euratom Nuclear Safety Directive.