Experimental and numerical investigation of the heat transfer between a high temperature reactor pressure vessel and the outside of the concrete confinement structure

[摘要] ENGLISH ABSTRACT: A high temperature reactor (HTR) generates heat inside of the reactor core throughnuclear fission, from where the heat is transferred through the core and heats up the reactor pressure vessel (RPV). The heat from the RPV is transported passively through thereactor cavity, where it is cooled by the reactor cavity cooling system (RCCS), throughthe concrete confinement structure and ultimately into the environment. The concreteconfinement structure can withstand temperatures of up to 65°C for normal operatingconditions and temperatures of up to 125°C during an emergency. This project endeavours to research the heat transfer between an HTR's RPV and the outside of theconcrete confinement structure by utilising three investigative approaches: experimental,computational fluid dynamics (CFD) and analytical.The first approach, an experimental analysis, required the development of an experi-mental model. The model was used to perform experiments and gather temperature datathat could be used to verify the accuracy of the CFD simulations. The second approachwas a CFD analysis of the experimental model, and the external concrete temperaturesfrom the simulation were compared with the temperatures measured with the experimen-tal model. Finally, an analytical analysis was performed in order to better understandCFD and how CFD solves natural convection-type problems.The experiments were performed successfully and the measurements taken were com-pared with the CFD results. The CFD results are in good agreement with the Dryexperiments, but not with the Charged experiments. It was identified that the inaccurateresults for the CFD simulations of the Charged experiments arose due to convective heatleakage through gaps in the heat shield and between the heat shield and the sides of theexperimental model. A computer program was developed for the analytical analysis andit was established that the program could successfully solve the natural convection in asquare cavity - as required.

[发布机构] Stellenbosch University