Activities in Spain on the integration of probabilistic and deterministic safety analysis methods. Discussion on their applicability to DEC-A scenarios

This paper presents a summary of theoretical and applied achievements in the field of integrated methods of nuclear safety analysis produced by Spain's nuclear safety community. These integrated methods combine deterministic as well as probabilistic tools and include the approaches termed "Extended Best-Estimate Plus Uncertainty" (E-BEPU), dynamic PSA (DPSA), and probabilistic quantification of safety margins. In the three fields, the Spanish contributions have been substantial, and, in some cases, certainly pioneering. These works have been promoted and performed by Spain's Regulatory Authority (CSN), in collaboration with some Spanish university groups and foreign research groups. The paper describes how these integrated methods can be useful in the analysis of Design Extension Conditions (DEC) of nuclear plants, especially in the subcategory DEC-A, formed by scenarios DEC where the core or nuclear fuel is not severely damaged. Finally, a prospective of future activities on the development and application of integrated methods is presented.