Nuclear design of an integrated small modular reactor based on the APR-1400 for RO desalination purposes

The United Arab Emirates lacks conventional water resources and relies primarily on desalination plants powered by fossil fuels to produce fresh water. Nuclear desalination is a proven technology, cost-competitive, and sustainable option capable of integrating the existing large-scale desalination plants to produce both freshwater and electricity. However, Small Modular Reactors (SMRs) are promising designs with advanced simplified configurations and inherent safety features. In this study, an Integrated Desalination SMR that produces thermal energy compatible with the capacity of a fossil fuel-powered desalination plant in the UAE was designed. First, the APR-1400 reactor core was used to investigate two 150 MWth conceptual SMR core designs, core A and core B, based on two-dimensional parameters, radius, and height. Then, the CASMO-4 lattice code was used to generate homogenized few-group constants for optimized fuel assembly loading patterns. Finally, to find the best core configuration, SIMULATE-3 was used to calculate the core key physics parameters such as power distribution, reactivity coefficients, and critical boron concentration. In addition, different reflector materials were investigated to compensate for the expected high leakage of the small-sized SMR cores. The pan shape core B model (142.6132 cm diameter, 100 cm height, and radially reflected by Stainless Steel) was selected as the best core configuration based on its calculated physics parameters. Core B met the design and safety criteria and indicated low total neutron leakage of 11.60% and flat power distribution with 1.50 power peaking factor. Compared to core A, it has a more negative MTC value of -6.93 pcm/degrees F with lower CBC. In a 2-batch scheme, the fuel is discharged at 42.25 GWd/MTU burnup after a long cycle length of 1.58 years. The core B model offers the highest specific power of 36.56 kW/kgU while utilizing the smallest heavy metal mass compared with the SMART and NuScale models.