A Study of Flow Instability and Safe Limit in Supercritical Water Natural Circulation Loop

Abstract

In the Generation-IV nuclear reactor concept, Supercritical Water Reactor (SCWR) is one of the most advanced technology types of reactor. Supercritical water (SCW) is used as a working fluid in the SCWR due to its various advanced features such as high specific heat capacity, high thermal efficiency than subcritical fluid, elimination newlineof dryer, separator and steam generator, and compact size makes system economical. SCW was used as a primary coolant fluid in many forced convection (FC) types newlineSCWRs, in the last two decades. The essential components of the natural circulation loops (NCLs) consist of a heat sink, source, and pipes. The pipes of the loop are connected in such a way that makes a continuous flow path of the working fluid inside the loop. NCLs are an automatic operating system that transfers heat energy from a source to a sink due to density newlinedifferences in the loop, without any physical contact between them. Similarly, two- newlinephase and supercritical natural circulation loops (SCNCLs) are able to generate density differences between the heat source and sink. Thereby, two-phase NCLs are used in boiling water reactors (BWRs), whereas SCNCLs are used in SCWRs to remove heat from the core newline