Dimensional analysis consists of identifying parameters influencing any process and grouping them into a set of independent dimensionless numbers using Buckingham’s pi theorem. It is a powerful tool for correlating data obtained from experiments where each of the controlling parameters is systematically varied.

In this case study, dimensional analysis is applied to study the heap forming characteristics of the core debris generated during a Fuel Coolant Interaction (FCI) following an accident in a fast breeder reactor. The study of debris heaping behaviour on the corecatcher plate is important from recriticality concern and also from cooling considerations to ensure the safety of the reactor main vessel after the accident.  The debris heap is characterized by the static repose angle. The complete set of dimensionless groups defining the heaping phenomenon is derived. It is shown that repose angle of the heap is a function of Particle Reynold’s number (Re), Froude number(Fr) and Archimedes number (Ar) for a system with  geometry and density similitudes.

A set of experiments is conducted with lead spheres in water to mimic the heaping behaviour of core debris on corecatcher plate in sodium, their density ratio being similar. The repose angle is extracted from the digital image of the heap. From the experimental data, the functional dependence of repose angle on Re, Fr and Ar is determined and an empirical correlation is developed using regression analysis.