Plant-wide simulation model for transient studies on the Xe-100

Abstract

This paper gives an overview of the plant-wide simulation model that is used by X-energy LLC for developing their plant design and control philosophy, as well as assessing plant upset conditions. The simulation model was created in Flownex® thermal-fluid system simulation software, which solves mass, momentum and energy equations for compressible, incompressible and homogeneous two-phase flow. The plant model encompasses all major components, from reactor to condenser, including main control loop elements. The paper pays particular attention to the validation of the two-phase flow framework used for the secondary steam cycle. Two steady-state validation cases are done using operational data from the THTR. Validation of transient operation is done by simulating density wave oscillations, a type of system-level boiling phenomenon. This is regarded as a thorough test of transient capability because of the challenges this phenomenon poses to several aspects of the calculation and to the consistency of the code as a whole