Molten salt modelling capabilities in SPECTRA and application to MSRE and Mk1-PB-FHR

•The paper describes SPECTRA capabilities with respect to molten salt reactors.•Specific MSR capabilities are highlighted and explained.•Noteworthy are flexible property and correlation input as well as delayed neutron and fission product transport.•Comparison is shown to MSRE data.•Simulation of Mk1-PB-FHR is presented. In support of extensive experimental irradiation program on molten salt technology at NRG in the Netherlands, system thermal hydraulic modeling capabilities are being developed in the SPECTRA code. This paper describes the (fueled) molten salt capabilities developed and presently available in the code. These include obviously flexible input of properties and (heat) transport correlations, delayed neutron precursor drift, fission product behavior, noble gas behavior, noble metal behavior, noble metal extraction, and chromium leaching and deposition. The paper will introduce the models developed and where possible their application to the Molten Salt Reactor Experiment (MSRE) data and simulation of the Mk1-PB-FHR.