There is disclosed a hybrid assessment tool. In an embodiment, the tool includes code to determine initial cut sets from a model; code to modify the initial cut sets; code to create a logic model representative of a subset of failure combinations created from the initial cut sets; code to convert the logic model representative into a binary decision diagram (BDD); and code to quantify the risk for a scenario. There is disclosed a method of quantifying risk of a scenario. In one embodiment, the method includes determining initial cut sets from a model; modifying the initial cut sets; creating a logic model representative of a subset of failure combinations created from the initial cut sets; converting the logic model into a BDD; and quantifying the risk for the scenario using the BDD. Other embodiments are also disclosed.
 The United States Government has certain rights in this invention pursuant to Contract No. DE-AC07-05ID14517 between the United States Department of Energy and Battelle Energy Alliance, LLC.