Advancement of elemental analytical model in LEAP-III code for tube failure propagation

Abstract

If pressurized water or its vapor leaks from a ruptured heat transfer tube in a steam generator of a sodium-cooled fast reactor, a high-velocity, high-temperature, and corrosive jet with sodium-water chemical reaction may cause tube failure propagation. In this study, an analytical method was developed to predict the occurrence of tube failure propagation by overheating rupture. This method consists of the elemental analytical models for a sodium-side temperature distribution formed by a reacting jet, water-side thermal hydraulics, heat transfer between a fluid and a tube, and tube failure by internal pressure. To evaluate the tube failure propagation in a short computation time, these models are based on the experimental data, semi-theoretical correlations, or one-dimensional equations. Applicability of the proposed method was investigated through the numerical analysis of an experiment on water vapor discharging into the liquid sodium. This analysis demonstrated that the method could predict the occurrence of overheating rupture and provide conservative results. While the proposed method is useful for high-speed computations, this method evaluates a high temperature region with a large conservativeness in some cases. To improve this conservativeness, a Lagrangian particle model for the reacting jet was also developed as an alternative method. The numerical analysis by this model showed that the discharged gaseous particles spread with particle-particle and particle-tube interactions.

Keywords

• sodium cooled fast reactor
• steam generator
• sodium water reaction
• tube failure propagation
• overheating rupture
• numerical analysis