Authors: G. Vikram, M. Rajendrakumar, R. S. Kumar, K. Natesan
Year: 2025
Industry: Nuclear & SMR
Keywords: Use FSE, Dynamic, SFR, Validation
ABSTRACT
Plant dynamics analysis plays an important role in the design and operation of sodium-cooled fast reactors (SFRs). This paper presents the development and validation of a plant dynamic model for an SFR using the Flownex code, a general-purpose thermal-fluid simulation software. A general modelling philosophy is provided for building Flownex models to simulate key components of the SFR, including the core, plenum, pipelines, intermediate heat exchanger (IHX), and pump. A new user-defined script for SFR kinetics calculations has been developed, which enables neutron kinetics calculations based on the point kinetics model with reactivity feedback effects. The procedures for simulating heat sources, sinks, and the inclusion of temperature-dependent sodium fluid properties are discussed in detail. These models and approaches are designed to optimize execution speed while maintaining good accuracy based on practical experience with the code.
A plant dynamics model is developed for the “Fast Flux Test Facility (FFTF)” reactor using Flownex and is used to simulate the “Loss Of Flow Without Scram (LOFWOS)” test #13. The good agreement observed between the simulation results of various SFR parameters and the experimental data demonstrates the suitability of the Flownex code for advanced plant dynamics studies of SFRs. However, the current system modelling approach has certain limitations, primarily due to the neglect of spatial (multidimensional) effects and the simplified treatment of feedback reactivity components. Potential directions for future improvements are also discussed in this paper.