Validation database for pool scrubbing: an update

Pool scrubbing is a key passive mechanism for retaining Fission Products (FPs) during Severe Accidents (SA) in nuclear power plants, making accurate prediction of this process essential for safety analysis and accident management. This paper presents a substantial extension and critical review of the international experimental database for pool scrubbing, surveying over 900 tests from almost 50 experimental programs published up to 2025. A rigorous adapted adequacy analysis methodology was systematically applied to assess the representativeness (accuracy, fidelity, and reproducibility) and completeness of the data. The figure of merit selected was the Decontamination Factor (DF). The screening process drastically reduced the dataset: only 106 experiments were ultimately classified as Qualified for Validation (QfV), representing approximately 12% of the total documented tests. This new QfV validation matrix broadly covers the expected Boundary Conditions (BCs) of the scrubbing process in risk-relevant designs and accidental scenarios, and enables the derivation of empirical trends for validating the influence of single BCs on the DF (e.g., flow rate and saturation ratio effects) in pool scrubbing models. The analysis also highlights key remaining data gaps, specifically the scarcity of experiments involving gaseous and soluble FP, and the lack of scenario-dependent experimental programs. This validated database establishes a solid, systematic foundation for comprehensive code assessment and improvement, with the ultimate goal of enhancing predictive capabilities to strengthen source term predictions during severe accidents of current and future reactor designs.