Thermal Design Aspects of a Fuel Channel for the Canadian Supercritical Water Reactor Concept
Canada is currently developing the Canadian supercritical water reactor (SCWR): a Generation IV pressure tube type reactor that builds upon the knowledge of existing and advanced CANDU reactors to achieve enhanced safety, improved economics, sustainability and increased proliferation resistance. The Canadian SCWR reference design has vertical pressure tubes (fuel channels) contained within a pool of low temperature and pressure heavy water (moderator). The pressure tube is thermally insulated from the hot primary coolant by a zirconia based ceramic. In combination with a passive moderator cooling system, a fuel channel designed with appropriate thermal resistance has the potential to offer enhanced safety by sufficiently removing decay heat to maintain fuel cladding integrity following an accident with total loss of primary coolant.
This presentation discusses the thermal design aspects of achieving enhanced safety and the impact this has on reactor design and normal operation. A preliminary safety analysis was performed with the thermalhydraulic code CATHENA and the results were used to evaluate the parameters important to enhanced safety and its impact on moderator thermalhydraulics. A parametric evaluation of the fuel channel design and moderator thermalhydraulics was performed and compared with a more detailed CFD analysis to evaluate the range of possible operating conditions. In addition to this work, small scale fuel channel experiments were performed and the heat transfer data compared to a finite element thermal-elastic model. Together, the results of this work are being used for evaluating detailed fuel channel design options. The presentation concludes by discussing some of the remaining fuel channel work to be completed for the Canadian SCWR conceptual design.