High pressure superheated or saturated steam line breaks in a nuclear power plant generate high speed jet flows and blast waves. The jet loads and blast wave pressures can damage critical nuclear power plant components. An accurate assessment of these effects including uncertainty quantification (UQ), is essential to confirm that design is robust enough to handle jet flows and blast waves from postulated steam line breaks. This paper presents the verification and validation of a computational model created using a commercial CFD code for making such assessments. The verification and validation process involves the steps of application space parametrization, Phenomena Identification and Ranking (PIR), CFD model lockdown, selection of validation dataset, and calculation of formal validation metrics. The Uncertainty Quantification in the actual application should include the propagated validation uncertainties from the validation test problems.