Development of a microfluidic setup to study the corrosion product deposition in accelerated flow regions

Abstract

CRUD (Chalk River Unidentified Deposit) forms in the water circuits of nuclear reactors due to corrosion of structural materials and the consequent release of species into the coolant. The deposition of CRUD is known to occur preferentially in regions of the primary circuit of pressurised water reactors (PWRs) where the water flow accelerates. In order to investigate this phenomenon, a micro-fluidic system, recreating plant conditions while using a simplified experimental set-up, was realised. A flow cell, comprising a stainless steel disc with a central micro-orifice, was used to create accelerated flow under representative operating conditions. By monitoring the pressure drop across the cell, the build-up rate (BUR) of CRUD within the micro-orifice was monitored in real time. By this setup, the conditions inducing deposition of CRUD under PWR conditions were emulated and CRUD deposition was induced in the accelerated flow region. Further effects associated with the presence of lithium hydroxide were investigated in real-time.