Analytical benchmarks for verification of thermal-hydraulic codes based on sub-channel approach

Over the last year (2007), preliminary tests have been performed on the Moroccan TRIGA MARK II research reactor to show that, under all operating conditions, the coolant parameters fall within the ranges allowing the safe working conditions of the reactor core. In parallel, a sub-channel thermal-hydraulic code, named SACATRI (Sub-channel Analysis Code for Application to TRIGA reactors), was developed to satisfy the needs of numerical simulation tools, able to predict the coolant flow parameters. The thermal-hydraulic model of SACATRI code is based on four partial differential equations that describe the conservation of mass, energy, axial and transversal momentum. However, to achieve the full task of any numerical code, verification is a highly recommended activity for assessing the accuracy of computational simulations. This paper presents a new procedure which can be used during code and solution verification activities of thermal-hydraulic tools based on sub-channel approach. The technique of verification proposed is based mainly on the combination of the method of manufactured solution and the order of accuracy test. The verification of SACATRI code allowed the elaboration of exact analytical benchmarks that can be used to assess the mathematical correctness of the numerical solution to the elaborated model.