A study of thermophysical and physicochemical characteristic of the KALLA experiment facility

Activities are currently underway across the world to build heavy liquid metal-cooled reactors. For example, the ALFRED and BREST-OD-300 reactor designs use lead coolant, while the MYRRHA and SVBR-100 reactors use lead–bismuth coolant. The high corrosive and erosive activity of the coolant requires control of oxygen concentration and flow velocity. Due to the complex geometry of the reactors cooling circuit flow, numerical simulation methods are used extensively to justify the operation modes for liquid metal coolants. Correct justification of the complex oxygen transport processes in liquid metals requires the detailed physicochemical computational model, which takes into account the major reactions of oxygen with the coolant and the structural materials. This paper presents a physicochemical model, which includes the following processes: erosion, growth, and dissolution of the two-layer oxide film, precipitation and dissolution of metal oxides in the circuit with subsequent deposition in a filter, and inflow of oxygen by the mass exchanger. The physicochemical model was implemented using the model of passive scalar, which allows simulating the impurity transport in the coolant. Capabilities of the presented model are demonstrated based on the results of investigating thermohydraulic and physicochemical processes at the KALLA laboratory experimental facility. The duration of the simulation is 1000 hr. The spatial distributions of metal oxides concentrations, areas of enhanced erosive activity, as well as mass of oxides deposited in the filter and the amount of oxygen entering the circuit have been obtained. The surface distribution of the oxide film thickness on the test facility surfaces contacting the coolant has also been calculated. Accounting for thermocouples and the manufacturing technology made it possible to improve the accuracy of calculating the thermohydraulic characteristics of the coolant flow compared to earlier studies.