Optimization of hydride fueled pressurized water reactor cores

Full text of publication follows: This paper reports the results of the thermal-hydraulic and economic analyses performed for hydride fueled PWR cores as part of a collaborative project on hydride fuels undertaken by MIT and UC Berkeley. The use of hydride fuels allows increased fuel to coolant ratios in a given core volume, and the achievement of higher burnups and thermal power from a core loading. A parametric study was developed to determine the optimum combination of lattice pitch, rod diameter, and channel shape - further referred to as geometry - for minimizing the cost of electricity associated with the use of UZrH1.6 fuel in PWRs. Results of the steady-state and transient thermal hydraulic analyses are presented here. These are integrated with the results from fuel performance and neutronics studies into an economic model to reveal the desired optimal geometries. The thermal hydraulic analysis determines the maximum power that can be achieved for a given geometry, subject to steady-state and transient design constraints. Steady-state constraints include MDNBR, pressure drop, fuel temperature, and fuel rod vibrations. Transient constraints include the consideration of LOCA, LOFA, and over-power events. The fuel performance and neutronics analyses determine the maximum achievable burnup for a given geometry, subject to constraints on fuel internal pressure and fission gas release, clad oxidation, clad strain, and reactivity. All results are included in the economic model, which calculates the front and back end fuel cycle, operations and maintenance, and capital costs. Optimal designs include geometries where hydride fuel offers cost savings over oxide fuel, as well as geometries offering the lowest overall cost of electricity. All studies are performed for both UZrH1.6 and UO2 fuels, and the methodology is successfully validated by comparison of the predicted power, burnup, and cost of electricity for UO-2 fueled cores with corresponding data from existing plants. (authors)