The aim is to bridge the gap between very accurate CFD models that require huge amounts of computation time and faster but limited one-dimensional or 1.5-dimensional models like RELAP. One path is currently being reseached by developing techniques to couple RELAP and CFD models. Another approach would be to develop more simplified CFD models (coarse mesh CFD) while a second approach would be to develop surrogate models based on reduced order modeling, input/output models and other techniques.
The research will have to identify the best strategy for different applications in MYRRHA (safety studies, control strategy studies, uncertainty quantification). The development of these models and techniques should be as rigourous as possible, based on mathematical analysis (Principle Component Analysis, response techniques, input/output surrogate modeling) and not only based on engineering judgement. This avoids human error but also makes the method more generic and applicable to a design that is still in evolution.
This study should lead to validated models (validated against detailed reference calculations) that are of use to the MYRRHA safety group. The models and transient studies should be compared to similar RELAP5-3D analyses, pure CFD analyses and the coupled RELAP5-3D/CFD work currently under development.
The main scientific challenge lies in the development of a method/strategy that is rigourous from a mathematical point of view and generic (design independent). This makes the research scientifically valuable even beyond the application to MYRRHA.
- S. Lorenzi, Improvement of the control-oriented modeling of the Gen-IV lead-cooled fast reactor: development of reduced order methods, PhD thesis, 2015
- A. Class, Coarse Grid CFD & Reduced Order Models, presentation at the SESAME Progress Meeting, 2016
- M. Hinze, S. Volkwein, Proper Orthogonal Decomposition surrogate models for nonlinear dynamical systems: error estimates and suboptimal control, Lecture Notes in Computational Science and Engineering, Vol 45, pp261-306, 2005