Development of MERCURY for simulation of multidimensional fuel behavior for LOCA condition

•A multidimensional entire fuel rod analysis module (MERCURY) which employs implicit scheme based on FEM, has been developed to simulate multidimensional fuel during LOCA.•The fuel models incorporated material properties as functions of burnup, an oxidation model at high temperature, a rod internal pressure model, and a burst criteria model.•The MERCURY was verified against the results by the commercial FEM software package code (ABAQUS).•The MERCURY shows good agreement against a separated effect test (PUZRY) as validation. During a loss of coolant accident (LOCA), the ballooning and rupture of fuel cladding can block coolant flow and reduce the coolability of a reactor, which can lead to violation of a safety criteria. It is crucial that fuel models consider how multidimensional thermomechanical behavior and burnup properties affect safety analysis and evaluation. In this study, a multidimensional entire fuel rod analysis module (MERCURY) based on the finite element method (FEM) was developed to simulate multidimensional fuel behavior during a LOCA. The MERCURY incorporated a transient thermal analysis model, a multidimensional gap conductance model, a nonlinear mechanical model, and a transient creep model as thermomechanical models. As fuel models, burnup-dependent material properties, an oxidation model at high temperature, a rod internal pressure model, and cladding burst criteria were developed. Each FEM-based model was verified against results using a commercial FEM package. Verifications demonstrated that the models were formulated and integrated correctly. As validation, the MERCURY simulated experiments (PUZRY) regarding cladding behavior out-of-pile at high temperature and high inner pressure, which is similar to the fuel condition during a LOCA. The simulation results show good agreement with measured hoop strain in experiment.