Valuation of BWR stability operating in natural circulation conditions

Nowadays, new concepts of nuclear reactors have been projected to work with mechanisms of natural circulation (NC). However, NC systems are very susceptible to several kinds of instabilities being necessary careful studies about such systems. In this work, a theoretical investigation about BWR stability during a transient of recirculation pump trip bringing the reactor to operate at NC conditions is presented. The simulations were performed using the RELAP5/MOD3.3 thermal-hydraulic code and the PARCS/2.4 3D neutron-kinetic code in a coupled way to predict the transient results. The power time evolution and the related thermal-hydraulic parameters were investigated during the transient to analyze the behavior of the reactor for this special operation condition of NC.

► We investigated BWR stability during a transient of recirculation pump trip.
► The pump trip brings the reactor to operate at Natural Circulation conditions.
► We used the coupled codes RELAP5 and PARCS to predict the transient results.
► We examine the power time evolution and the related thermal-hydraulic parameters.