Authors: C.G Du Toit, P.G. Rousseau, J.S. Jun, M.W. Kim
Year: 2016
Industry: Nuclear & SMR
Keywords: Use FSE, Transient, HTR, RCCS, Verification
ABSTRACT
The reactor cavity cooling system (RCCS) of a high temperature reactor must be able to operate naturally or passively safe to avoid accidents due to human error or the failure of components. The RCCS under consideration in this investigation is an air-cooled system with a U-tube-like configuration. It consists of an annular downcomer channel which is connected via a bottom-header to 220 riser tubes. The down-comer and risers are connected to the atmosphere via inlet and outlet manifold systems respectively. In this study the entire system is simulated using two network codes, GAMMA+ and FLOWNEX. The purpose of the study is to investigate the effect that a positive pressure transient acting on the outlet of the RCCS will have on the performance of the cooling system. The agreement between the results obtained with the two codes is good and serves as a verification of the methods that are used. It has been found that the pressure increase may result in a reversal in the flow. When the pressure returns to its original value the flow does not reverse to the original flow direction. Although the heat removal is not severely affected, it leads to an unacceptable increase in the temperature of the concrete containment. This should be taken into account in the design of the RCCS system as it relates to the reactor safety case.