Reduction of the Coolant Void Reactivity Effect in a CANDU Lattice Cell

Abstract

<p>A positive feedback mechanism linking reactor power and loss of coolant exists in the current configuration of the CANDUˣ reactor. This mechanism creates a "coolant void effect" which is accommodated in both the safety system and control system designs: .although a political incentive exists to reduce the effect's magnitude. This dissertation includes a review of current methods and knowledge in the area of CANDU lattice cell analysis of the coolant void effect, presented in two parts: (1) an investigation of the methodology and modelling, and (2) an investigation of the contributing reactor physics. This study also explores several routes toward the goal of reducing the coolant void effect, drawing from both existing work and original contributions. A novel approach to CANDU fuel design is defined, combining the concepts of coolant displacement, concentritubular fuel, and differential uranium enrichment. Several variations of the new design are discussed, as well as practical difficulties that would be associated with the realization of this design. Finally, a corrective algorithm is developed and utilized which compensates for a modelling deficiency arising in the simulation of tubular fuel.</p>