Effect of Boundary Layer Formation on Energy Interaction Between Fuel Pebbles in Gas Cooled Nuclear Reactors Ugur Guven 1 , Gurunadh Velidi 2 , Vignesh V 2 , Arun Narasimhan 2 , Sampath Emani 2 1 Nuclear Energy Institute, Istanbul Technical University, Turkey 2 Departments of Aerospace Engineering, University of Petroleum and Energy Studies, India Abstract. Gas cooled Nuclear Reactors with the fuel pebble arrangement will create a great efficiency in the power generation. Helium as a coolant is more effective in exchanging heat between fuel pebbles and the coolant and maintains good advection ratio in the core. However, one of the more important points in nuclear power generation is to increase the heat production rate as much as possible. But, in real life, all nuclear reactors are bound in their maximum efficiency by the Carnot cycle. Hence, the only thing that can be done is to increase the heat transfer gradients in order to help increase the overall efficiency of the heat production system in a nuclear reactor. One of the most effective ways of increasing the heat transfer capacity to a flow is to utilize turbulence and therefore increase the amount of heat that is being transferred from the fuel pebble, which is undergoing the fission reaction, to the coolant itself. Naturally, various adverse pressure gradients which will become predominant in energized turbulent boundary layers, will also have to be taken into account. This paper will address the effect of boundary layer formation on energy exchange and heat interaction within the core. Moreover, the flow conditions that are designed over the fuel pebbles with grater turbulence will help to improve the energy exchange between the nuclear fuel pebble and the coolant. In this paper, we will demonstrate the added heat ratios with the help of CFD simulations with Helium as the coolant and it will address the effectiveness of energy exchange with the help of boundary layer formation over nuclear spherical fuel pebbles in gas cooled reactors. Keywords: Fuel Pebble, Helium, Gas Cooled Rector, Thermal Boundary Layer, Velocity Boundary Layer, Energy Density. 1. Introduction One of the most important things in our world is to have more energy to meet our domestic and industrial needs. In the 21 st century, the amount of electricity that is used has more then quadrupled around the world as compared to 1930’s. Due to this, more and more innovative energy production methods are being utilized to produce the electricity that is needed by the civilization. Due to limitations in the efficiency of renewable energy sources and also due to the problems associated with fossil fuel sources, nuclear energy still remains one of the more viable options for creating electricity. Especially with the advancements in the last decade, more safer and more efficient means of creating electricity from a nuclear fission reaction has become possible. Especially, the advent of Generation IV reactors, along with safer methods of electricity production through gas cooled nuclear reactors; seem to be gaining more interest in these past few years. A significant concept in nuclear power production is to increase the amount of heat generated in the reactor itself. Due to limitations in the thermodynamic cycles, the best ideal efficiency which can be obtained is the Carnot cycle, which depends on the gradient between the highest temperature and the lowest temperature in the system [5]. Due to logistical limitations in the location placement of nuclear reactors, there is actually not much that can be done to improve this efficiency level. The coolest temperature will be the outside sea level average temperature of 17 C, while the highest temperature will depend on the nuclear fuel rods and the nuclear kinetics that are used in the nuclear reactor itself [1]. 2012 International Conference on Fluid Dynamics and Thermodynamics Technology (FDTT2012) IPCSIT vol. XX (2012) © (2012) IACSIT Press, Singapore