The HORIZON-2020 project on Management and Uncertainties of Severe Accidents (MUSA) meant a sound step forward in the application of uncertainty and sensitivity analysis (UaSA) in severe accident (SA) analysis. While a massive application was conducted for reactor and spent fuel pool scenarios, major challenges were found that might hinder an effective and systematic implementation of UaSA in the SA domain. This paper synthesizes the major accomplishments achieved by MUSA and identifies the challenges that were found, and through discussion, the path forward to move ahead is outlined.