E. Kitcher “Xenon-Induced Power Oscillations in a Generic Small Modular Reactor”, Ph.D. Dissertation, Nuclear Engineering, Texas A&M University, College Station, TX (2016).
In this work, a generic SMR design developed and analyzed with respect to xenon-induced power oscillations. A multi-physics coupling routine is implemented with MCNP/MCNPX for neutronics, semi-analytical single channel analysis for thermal hydraulics developed in-house and the SIGACE code from the IAEA for generation of Doppler broadened cross-sections for use with MCNP/ MCNPX. The coupling is fully automated using a PYTHON SCRIPT. The Power Axial Offset (PAO) and Xenon Axial Offset (XAO) parameters are chosen as the quantities of interest in order to quantify any potential oscillatory behavior observed. The methodology is benchmarked against literature for startup tests performed at a four-loop PWR in Korea. The pertinent features of the reactor are captured in the developed benchmark model within ten percent of the literature values. The results demonstrated that the developed methodology was indeed capturing the phenomena desired accurately. Subsequently, a high fidelity SMR core model is developed and assessed. Results of the analysis reveal a SMR design which is inherently stable at beginning of core life and end of core life under full power and half power conditions. Sensitivity studies undertaken investigated the effects of axial discretization, stochastic noise and convergence of the Monte Carlo tallies in the calculations of the PAO and XAO parameters. All are found to be quite small and the inherently stable nature of the core design with respect to xenon-induced power oscillations is confirmed. Finally a preliminary investigation into excess reactivity control options for the SMR design is conducted confirming the generally held notion that existing PWR control mechanisms can be used with similar effectiveness. A possible replacement for soluble boron in the reactor coolant is discussed.