Causative Process Related Method for the Design of a Reduced Scale Test Facility for Boron Dispersion Analysis in the Pressurizer of Smrs

Pressurizers are important components placed in Pressurized Water Reactors (PWRs) and are responsible for pressure control. Although traditional PWRs have a continuous flow maintained by spray devices in order to promote mixing between primary coolant system and pressurizer water, one alternative for Small Modular Reactors (SMRs) is to replace surge lines and sprays by surge orifices aiming at homogenizing boron concentration in the whole primary system. Such process of homogenization is necessary in order not to promote power transients. This paper intends to compare thermal-hydraulic parameters obtained by a scaling methodology – Causative Process Related Method – with those derived by another scaling technique. The conservation equations representing boron concentration are derived for the two liquid regions inside the pressurizer. The scaling methodology is applied to these equations, providing dimensionless parameters necessary for boron dispersion similarity. By considering one-fourth symmetry and reduced scale for time (1/5) and space (1/200), a test facility based on these parameters (e.g., circulation flow and condensation rate respectively equal 0.00000335 m3/s and 0.0001 kg/s) is under construction and shall be used to evaluate boron dispersion in SMRs, providing reliable results with a reduction of costs. The evidence of trustful results is verified when normalized concentrations at the respective dimensionless times are compared for both model and prototype.