Dynamical System Scaling application to the design of a test facility for boron dispersion evaluation in iPWR-SMRs

Abstract

Pressurizers are relevant components of Pressurized Water Reactors (PWRs) aiming at pressure control. In contrast to traditional PWRs, Small Modular Reactors (SMRs) may have surge orifices in order to promote boron mixing with primary coolant, instead of spray devices and surge lines needed to minimize reactivity transients. This paper aims to demonstrate that the parameters of a test facility under development, obtained independently by Fractional Scaling Analysis and Causative Process Related Method, when applied to average boron concentration equations, represent faithfully boron dispersion in the pressurizer of an integral Pressurized Water Reactor/Small Modular Reactor (iPWR-SMR). The demonstration is accomplished by applying a recent scaling technique known as Dynamical System Scaling (DSS), whose fractional rates are time-varying, instead of being defined by initial (constant) terms. The design of such a test facility considers one-fourth symmetry and reduced time and volume scales so as to provide cost savings. Reliable results are obtained when an important DSS parameter – the temporal displacement rate – is compared for both systems, indicating a complete similarity for them.