Thermal hydraulic analysis of VVER-1000 nuclear reactor with dual-cooled annular fuel using K-ω SST Turbulence model

Dual cooled annular nuclear fuel which is an internally and externally cooled annular fuel has many advantages in heat transfer. One of the most prominent of these advantages is the ability to harvest more of this type of fuel that can be taken advantage to increase the thermal power of nuclear plants. In this paper, the core of a VVER-1000 reactor is designed based on the use of internally and externally cooled annular fuels and thermal hydraulic parameters of the fuel rods in this type of reactor is analysed. In addition, the amount of thermal power uprate in a VVER-1000 reactor using annular fuels is investigated. For this purpose, at the first, using of cell and core neutronics calculations codes the proper pitch length of fuel rods in the core is designed at Clean and Cold conditions. Then, using a simulated fuel rod in hot channel by simulation codes of CFD, thermo-hydraulic calculations are performed, and are compared with a conventional VVER-1000 reactor that does not use this kind of fuel. As one of the most important results of the analysis, annular fuel shows a sufficient margin available on DNB and fuel pellet temperature relative to cylindrical fuel. The margin amount seems accommodating a 129% power-uprate seems viable.