Key technologies for present-day and future advanced nuclear energy reactor systems encompass high temperature structural materials, fast neutron resistant core materials, and specific reactor and power conversion technologies (intermediate heat exchanger, turbo-machinery, high temperature electrolytic or thermo-chemical water splitting processes, etc.). Beyond the commercialization of best available nuclear reactor technologies now, it is essential to start now the development of breakthrough technologies that will be needed to prepare the longer term future for nuclear power:. These innovative systems include fast neutron reactors with a closed fuel cycle, high temperature reactors that could be used for process heat applications and fusion experimental and demonstration devices. This book (Essays on Nuclear Technology, Volume 1: 2018) is a collection of the Master Students’ Papers, for the Nuclear Technologies Class 2017/2018, Master’s Degree in Energy and Nuclear Engineering at Politecnico di Torino (Italy). Each group of authors developed a scientific review paper related to a class of materials used in fission or fusion nuclear power plants, with characterization of thermo-physical properties, thermo-mechanical, technological, uses, operating conditions, the effects of irradiation, the method of processing or preparation of the components for use in the nuclear field. Studies comparing different types of fission and fusion reactors, from the materials point of view, are available too.