[en] This paper reports on recent progress in the simulation of RD-14M single-phase pump rundown tests using the TUF pump model. TUF is an advanced two-fluid system thermalhydraulic computer code used in the safety and operational analysis of Ontario Hydro's nuclear reactors. RD-14M is an experimental facility possessing many of the physical and geometrical characteristics of a CANDU reactor heat transport system. In this paper, a recent series of RD-14M pump rundown experiments is described. The model used in TUF for simulating the steady and transient behaviour of the primary pumps is also presented. The pump model in TUF requires the user to input constitutive relationships in the form of constants for the homologous head and torque curves as well as a number of constants (e.g., moment of inertia, the coefficient of static friction, and the coefficient of dynamic friction) that are required for modelling the pump transient behaviour. Using the same methodology as that for characterizing the primary heat transport pumps in Darlington reactors, the constants required for modelling the RD-14M pumps were determined based on experimental data from three RD-14M rundown test (C9511, C9514 and C9519). The resulting TUF model of an RD-14M pump was then used to simulate a fourth independent RD-14M pump rundown test (C9513). Reasonable agreement was obtained between the computed results and experimental data. (author)