Woodruff School of Mechanical Engineering

NRE Seminar


“Flow and Heat Transfer Numerical ModelingDuring Quenching for a Postulated Loss-of-Coolant Accident”


Lander Ibarra


GE Power and Water


Thursday, November 15, 2012 at 11:00:00 AM


Boggs Building, Room 3-47


Dr. Chris Wang


During a hypothetical loss-of-coolant accident in water-cooled reactors, loss of reactor liquid inventory results in an uncovery of the fuel and resultant heatup when the liquid film vaporizes at the cladding surface. Immediately following the LOCA event, the Emergency Core Cooling Systems (ECCS) aim to restore the fuel to local saturation temperature through injecting subcooled supplemental coolant into the core. This creates a rapid and localized cooling of the fuel cladding temperature, resulting in a steep gradient in the surface temperature referred to as quench front. Advancement of the film front is controlled by the rate at which the liquid is heated to vaporization by the hot fuel surface so that along the fuel rod, heat is removed by a combination of conduction, convection and radiation. This results in significant thermodynamic non-equilibrium flow in the fuel channel were superheated steam exists throughout the core from the initial LOCA, the subcooled liquid injection and the generation of saturated steam from the film front. Improving the predictive capabilities of ECCS models to simulate such complicated phenomena is crucial in safety analysis since ECCS capacity may dictate core operating limits on local power production.

This seminar will discuss current thermal-hydraulic models and codes used in the nuclear industry to model the quenching during a postulated LOCA and will briefly discuss the state of research in this domain.


Lander Ibarra is currently working as an engineer at the Nuclear Safety & Radiation Protection for the GE-Hitachi Global Nuclear Fuels facility in Wilmington, NC. He received his BS in Physics from Le Mans University in 2003 (France), Engineering Diploma (2007) in Acoustics from l’Ecole Nationale Superieure d’Ingenieurs (ENSIM) du Mans (France), and MS (2007) in Mechanical Engineering from Georgia Tech. He is currently working in transient thermal hydraulics at GE-Hitachi, more particularly, in the domain of thermal-hydraulic stability. Additionally, Lander is working on his PhD in Nuclear Engineering at University of Pisa (Italy).