Passive core injection system with steam driven jet pump for next generation nuclear reactors

The steam driven jet pump (SDJP) is a device without moving parts, in which steam is used as an energy source to pump cold water from a pressure much lower than the steam pressure to a pressure higher than the steam pressure. In this study, a design of a passive core injection system (PCIS) with SDJP is given for application to Boiling Water Reactor (BWR). The operation range of PCIS depends on the operation characteristics of the SDJP. Thus, the operation characteristics of the SDJP has been investigated in terms of independent parameters, such as water temperature, pressure, and steam inlet pressure which is the driving force of the SDJP to obtain a wide operation range. The water tank pressure is chosen as 320 kPa to increase the maximum operation pressure of the SDJP. The supply water temperature is chosen as 15°C which is about room temperature, and the steam which comes from the reactor pressure vessel is assumed as saturated. The operation range of the SDJP in terms of the steam inlet pressure is obtained from 2 to 10.5 MPa. The study shows that when the discharge pressure increases, the discharge mass flow rate and the temperature increases as well. The probabilistic reliability of the PCIS with the SDJP is assessed as well. The reliability assessment of the PCIS with SDJP is investigated using a fault tree, and compared with the core injection system with turbine-driven pump. It is found that the PCIS with SDJP is more reliable than the core injection system with turbine-driven pump.