Study on coupling effect of CRUD growth and heat transfer on fuel rod

The deposits of corrosion products inside the PWR core (known as CRUD) will endanger the operational security of the reactor by mean of heat transfer and boron hideout. In this paper, a set of analytical method is proposed to simulate CRUD growth and heat transfer simultaneously of heater rod. CRUD growth involves a dynamic equilibrium of corrosion product deposition and deposits erosion to calculate the CRUD thickness. The CRUD interior heat transfer model evaluates the heat transfer mechanism based on the vapor-liquid-solid ratio within the porous media and calculates the overall heat resistance. The surface heat flux distribution model considers the bubble dynamic parameters in relation to the CRUD surface characteristics to determine the heat flux distribution. The comparison of predicted results with WALT experimental data yields a relative error within +/- 0.95 %, which indicates that the proposed method can precisely predict the alteration in thermal resistance during CRUD growth. As the thickness of CRUD increases, the heat transfer of the heater rod undergoes an initial enhancement and subsequent deterioration. Higher porosity results in lower cladding temperature, whereas a greater chimney area leads to higher cladding temperature. The wall heat flux has a positive correlation with the CRUD growth rate, while the flow rate and subcooling of the coolant inlet have an opposite tendency.