DETERMINATION OF HEAT TRANSFER PROCESS IN VERTICAL CABLE TUNNELS OF NUCLEAR POWER PLANTS UNDER REAL FIRE CONDITIONS

Abstract

The object of the study was heat and mass transfer processes occurring in vertical cable tunnels. The problem to be solved was the defini-tion of process mechanisms in the inner space of the tunnel. For this, field tests were conducted, mathematical models were created, and compu-tational experiments were conducted to estab-lish specific parameters that affect the tempera-ture regime of a fire in a vertical cable tunnel of a nuclear power plant. The dynamics of tem-perature changes with known geometric parame-ters and fire load were determined, and the ade-quacy of mathematical models built in the Fire Dynamics Simulator software was investigat-ed and computational experiments were carried out. It has been proven that they consist in deter-mining the temperature regime in a vertical cable tunnel of a nuclear power plant with known tech-nical and geometric parameters. Such studies have practical applications in the field of safety of nuclear power plants and the development of new technologies in this field. An important con-clusion of these studies is the possibility of deter-mining the fire resistance of building structures of vertical cable tunnels of nuclear power plants with the selection of the most severe temperature regime, according to the conducted field test. This means that research results can be used in practice in designing and evaluating the safety of such objects.The conducted research established that the temperature in the inner space of the tunnel can reach values from 1200 to 1400 °C. The fol-lowing factors influence the maximum tempera-ture value and the maximum time to reach the maximum temperature in the fire cell: fire load, height and area of the tunnel. With a lower fire load, the maximum temperature in the verti-cal cable tunnel of the nuclear power plant was 75 % lower. Therefore, the results of these stud-ies have a direct practical application in the field of safety of nuclear power plants and can be used to improve and develop new technolo-gies in this field