Analyzing the effect of deformed pins in LMFR Rod Bundles

LMFR rod bundles can be designed with grid spacers or wire wraps. In both types of designs, pins may deform due to tension of the pre-stressed wires, contact pressure between clad and adjacent rods and/or wires, thermal and irradiation clad creep, irradiation-caused swelling and fuel burnup. In order to analyze the effect of such deformations on the peak temperature and temperature distribution, and in order to validate a simulation methodology, a series of experiments in water and liquid metal for grid-spaced and wire-wrapped liquid metal cooled fast reactor rod bundles is being conducted in Europe. These experiments are supported by numerical analyses which will be described. Experiments in water bundles aim at validating the simulated flow field around a deformed pin, while at the same time giving a first impression on the validation of the temperature field. Similar experiments in liquid metal rod bundles aim to validate the temperature field in the simulations. The paper will provide a description of the various experiments and will subsequently focus on the numerical support to these experiments.