The TRANSURANUS mechanical model for large strain analysis

The TRANSURANUS fuel performance code was extended in order to take into account large creep strains for the simulation of clad ballooning occurring during loss-of-coolant accidents (LOCA). While the first order theory gives very good results for small strains below approx. 5%, simulating large strains implies numerical instabilities due to the violation of the volume balances. To this purpose, an extension of the algorithm used in TRANSURANUS was proposed and verified adopting different solution methods : an analytic solution and finite element calculations by means of COMSOL. In particular, creep calculations were carried out applying a Norton law that defines cladding creep strains under varying stress conditions. The verification against the numerical solution given by COMSOL and the analytic solution shows an excellent agreement of the radial profiles of stresses and strains. The extended TRANSURANUS code was applied to the simulation of various cladding ballooning tests carried out in the framework of the EXTRA project, and of the IFA650.2 case of the FUMEX-III exercise. The impact of the new algorithm on the predicted time-to-burst and clad strain was assessed pointing out the effect of different failure criteria.

DI MARCELLO Valentino;  SCHUBERT Arndt;  VAN DE LAAR Jacques;  VAN UFFELEN Paul; 

2014-08-25

ELSEVIER SCIENCE SA

JRC85530

0029-5493,   

http://www.sciencedirect.com/science/article/pii/S0029549314003008,    https://publications.jrc.ec.europa.eu/repository/handle/JRC85530,   

10.1016/j.nucengdes.2014.04.041,