Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

Xenon Dynamics of AHWR

Large core reactors where the core dimension is significantly large compared to the migration length of neutron are more susceptible to xenon instability due to local perturbations. Advanced Heavy Water Reactor (AHWR) is being designed for on-power refueling. Therefore, refueling or movement of control devices in AHWR causes local perturbation. Preliminary modal analysis of AHWR equilibrium core also showed that the eigenvalue separation between fundamental mode and 1st azimuthal mode is small indicating its susceptibility to xenon oscillation in azimuthal plane. Therefore, xenon dynamic studies for AHWR with explicit xenon calculations were carried out using diffusion theory based computer code and the gain in reactivity due to on-power refueling was compensated by suitable movement of control devices. The reactivity feedback due to coolant density and fuel temperature variations were also duly accounted. The paper describes about behavior of AHWR core due to introduction of different reactivity perturbations.