Implementation of probabilistic assessments to support the ASTRID decay heat removal systems design process

•Probabilistic assessments for ASTRID DHR function.•Illustration of the added value of combining probabilistic and deterministic approaches at the earliest stage of design.•Simplified software developed by CEA to determine the minimal DHR systems requirement to respect decoupling criteria.•Limitations of the conventional FT/ET static approach.•Development of dynamic approaches and comparisons based on simplified DHR systems design.