Faculty of Energy Systems & Nuclear Science
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The Faculty of Energy Systems & Nuclear Science (FESNS) offers a variety of honours degree options in Sustainable Energy Systems, Health Physics and Radiation Science, and Nuclear Engineering. The Nuclear Engineering program is the only undergraduate honours degree in Canada.
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Browsing Faculty of Energy Systems & Nuclear Science by Author "Bereznai, George"
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Item A benchmarked dynamic model of xenon behavior in a molten salt reactor(2019-12-01) Price, Terry J.; Bereznai, George; Chvala, OndrejMolten salt reactors are a type of nuclear reactor that are being considered for deployment in the fourth generation nuclear power technology. Molten salt reactors use molten a alkali / actinide halide salt melt at temperatures far in excess of temperatures found in a typical pressurized water reactor. This thesis focuses on graphite moderated reactors with fluoride as the halide. The salt melt, called the fuel salt, is circulated between a moderator and a heat exchanger. While within the moderator, the dissolved actinides undergo fission and generate heat. Among products of nuclear fission is gaseous xenon, and in particular the isotope xenon-135 that acts as a neutron absorber. In solid fueled reactors, the xenon is effectively static and trapped within the fuel matrix. In a molten salt reactor, conversely, the fuel matrix is the mobile, circulating fuel salt that transports the xenon along with the rest of the fuel. This thesis focuses on modeling the behavior of xenon in a molten salt reactor. Existing literature in the field is reviewed and compiled. A model of xenon behavior in a molten salt reactor (the Molten Salt Reactor Experiment in particular) has been developed and the model is presented in this thesis. The model is benchmarked against experimental data using best available data, then minimal necessary justifiable adjustment is made to model parameters in order to fit the model to the experimental data. As a result this model is able to fit two transients, something that no xenon model of the molten salt reactor experiment has been able to do previously.Item A Computational Fluid Dynamics based model that predicts wall shear stress in CANDU outlet feeder pipes(2018-01-01) Wijayaratne, Uditha; Bereznai, GeorgeWall thinning of carbon steel in CANDU reactor outlet feeder pipes due to Flow Accelerated Corrosion (FAC) is identified as one of the challenges for CANDU reactors since it would force them to shut down due to safety reasons. Several models have been developed over time to predict the corrosion rate (i.e. the rate of wall thinning) of CANDU outlet feeders. These models are developed based on the corrosion chemistry and the mass transfer theories on growth and removal of the protective magnetite layer on the outlet feeder pipe surface. The magnetite layer is acting as a protective layer for the carbon steel feeder pipes by avoiding further corrosion. However, due to the wall shear stress that exerts on the feeder pipe wall, this protective layer is flushed away with the primary heat transport fluid. Wall shear stress is identified as one of the crucial factors behind FAC. Other parameters such as Fe ion concentration, fluid temperature, and pressure would remain within a certain range for a typical CANDU reactor. Still, the distribution of wall shear stress highly depends on the physical arrangement of the outlet feeder pipes. Therefore, wall shear stress would change drastically from one feeder pipe to another resulting in a higher degree of impact on the rate of wall thinning due to FAC. The model developed in this study predicts the maximum wall shear stress on the first bend of a particular feeder pipe considering the fluid Reynolds number, the bend angle and the linear length from the grayloc hub to the first bend. The model is developed using the wall shear stress distribution results generated by Computational Fluid Dynamics (CFD) studies using Siemens NX. The wall shear stress results from the model is then compared against the rate of wall thinning data available for the reactor 01 of the Darlington Nuclear Generating Station as well as some other models available in the literature. iii The model shows a good trend of predicted wall shear stress values against the rate of wall thinning data available. At this stage, the model can be used to identify the feeder pipe with the highest rate of wall thinning due to FAC among a set of given feeder pipes with 2” or 2.5” nominal diameters. This model can be used to identify the optimum feeder pipes for wall thickness measurements during routine maintenance and hence replace the required feeder pipes to avoid any unplanned shut down due to safety reasons.