Design Study on the Effects of Relative Diameters in the Reactor Vessel and Riser on the Performance Characteristics of a Small Modular Reactor driven by Natural Circulation

摘要

Small Modular Reactor (SMR) is one of the emerging energy technologies that meet the standards of safety, efficiency and sustainability required for the next generation. Most of the leading SMRs under development worldwide have an integral reactor vessel with the lower positioned core as a heat source and the upper positioned steam generator as a heat sink. Hot water from the core goes upwards through a riser, and the cold water from the steam generator comes down through an annular passage between the riser and the reactor vessel. Some SMRs are designed to be driven by natural circulation for normal power operation. The present work focuses on the viability of such designs and their operating performance which is bound to be affected by the system's geometric and hydraulic parameters greatly. Numerical simulations of conservation equations for mass, momentum and energy considering buoyancy forces are carried out to gain an insight for the effects of various geometric and hydraulic parameters such as diameters and resistances. To conclude, it is suggested that the diameters of the reactor coolant passage are maintained as uniform as possible for the more uniform temperature distribution and larger mass flow rate as required.