Severe accident sensitivity and uncertainty estimation using MELCOR and RAVEN

Abstract Today, using a best-estimate approach is key factor in the simulation and prediction of thermal-hydraulic other multi-physics phenomena occurring during nuclear severe accidents. The requires quantification both epistemic stochastic uncertainties safety codes to be effective. This assessment approach, named Best Estimate Plus Uncertainty (BEPU), being pursued as an alternative traditional deterministic analyses that are intrinsically conservative with not clearly defined margins. While results expressed terms set calculated values parameters, methodology, uncertainty ranges for parameters. International Technical Nuclear Community has made great efforts develop methods tools sensitivity accident codes. In this framework, Sapienza University Rome developed new Python script use RAVEN tool application BEPU within performed MELCOR. aim paper show capabilities coupling between MELCOR by performing statistical analysis estimate range evolution scenario.