Prediction of Thermodynamic Properties and Phase Behaviour of CANDU Nuclear Reactor Fluid Coolant Using the SAFT-VR Mie Equation of State

Canadian Deuterium Uranium Nuclear reactors (CANDU) form an essential power generation source for Canada and a multitude of European countries. CANDU reactors are characterised by their use of deuterium oxide as coolant as opposed to conventional light water of carbon dioxide coolants used in most nuclear reactors. However, CANDU reactors suffer from deuterium oxide radiolysis - the splitting of coolant to deuterium and oxygen gas. This poses a major threat to the safe and economic operation of CANDU reactors over their lifetime. Hence, clear separation and recombining process of deuterium and oxygen back to deuterium oxide is essential. In light of this, this research paper proposes the first theoretical models of deuterium oxide and the deuterium oxide + oxygen + deuterium mixture present in CANDU reactors. The models of the pure components and mixtures were devised using the SAFTVR – Mie equation of state along with computational techniques to estimate the parameters required by the equation of state to generate the complete pure and mixture models. The models are used to predict crucial physical properties of deuterium oxide and the vapour-liquid mixture under standard operating conditions as well as CANDU operating conditions. The devised models demonstrate excellent accuracy, providing < 5% AAD for the pure deuterium oxide, oxygen and deuterium models as well as the mixture system. The aim of the devised models is to be used in shortlisting the possible separation and recombining techniques.