Application of model order reduction techniques to space-time kinetics model of AHWR

Advanced Heavy Water Reactor (AHWR), a large nuclear reactor in which heat removal is based on natural circulation of light water in coolant channels, is described by an 80^th order model for accurate representation of its core neutronics behavior. The model, besides being nonlinear, is stiff and control design and analysis studies for AHWR are accompanied by serious numerical ill-conditioning problems. Hence, there is a strong motivation for obtaining reduced order model for AHWR. In particular, the application of model order reduction based on Davison´s and Marshall´s dominant mode retention and Singular Perturbation techniques has been explored. Also, their performance, relative to each other, has been assessed by comparing the characteristics of the three model reduction techniques with the characteristics of the original higher order model. All of these three techniques are found to be very effective in obtaining a lower order simpler models for AHWR.