A possible substitution of UO 2 for research purposes is the cerium dioxide (CeO 2 ) owing to its chemical and physical properties. Neutronic properties are different and fission is absent in the case of CeO 2 ; however, similarities were studied recently to have a possibility to compare the neutronic influence of secondary additives into the matrix. This paper deals with increasing the thermal conductivity of UO 2 nuclear fuel on surrogate material (CeO 2 ); the main focus of the research is given on the sintering behaviour of CeO 2 . The incorporation of highly thermally conductive material (SiC) is the investigated concept of thermal conductivity enhancement. Conventional sintering and spark plasma sintering (SPS) were applied to compare the behaviour of CeO 2 and UO 2 reported in the literature. High temperature thermal conductivity measurements did not confirm the positive influence of SiC additive inside the CeO 2 matrix mainly due to grain boundary disruptions. Similar behaviour was also previously reported for UO 2 pellets with SiC.

The most researched material in nuclear power industry is uranium dioxide however due to strict safety and sanitary restrictions this material can be researched only in specialized research institutes and universities which have sufficient technological background. For this reason it can be suitable to find material which would show physical properties similar to UO2 but would not suffer by the strict limitations in storage and handling. In this case much more workplaces could be incorporated in the material research and the list of investigated problems could be significantly enlarged. One of the possible substitutional materials is the cerium dioxide (CeO2) which shows similar chemical and physical properties like UO2 and in some cases shows also similar neutronic properties. The laboratory research was focused on comparing of the basic neutronic properties. For the comparison of nuclear properties the JANIS software [1] was used as it contains cross section libraries of both materials. It will be shown that similarity of both materials is significant and in several cases application of cerium dioxide as alternative material is possible with sufficient accuracy. As an example of the use of CeO2, research of influence of the SiC content on the reactivity of nuclear fuels is presented in this work.

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Great operational challenges are placed on nuclear power plants. These challenges are usually reflected in the expansion of fuel cycle length, long-time operation or power uprates. The one way is to optimize the equipment or replace it with equipment with higher efficiency. The second way is to optimize the fuel and its cladding. In this area it is possible to work mainly on the development of new materials which have better nuclear or mechanical properties. Nuclear power industry is a conservative one. It is necessary to have a detailed knowledge of materials properties of used equipment. Knowledge of the materials behavior is particularly required in the environment where the materials are exposed to neutron flux. This article focuses on new promising materials that can be used in a nuclear fuel, a nuclear reactor or its closest vicinity. Carbon nano materials can be included among these types of materials. Composite materials have generally improved mechanical and thermal properties with addition of nanoparticles. However the additives itself have an impact on the behavior of the neutron field. This article describes an experiment that examined the behavior of neutrons in carbon nano fibers, carbon nano tubes and nano wires of aluminum oxide. The main goal of the experiment was to determine how neutron scattering is affected, when the sample is exposed to neutron beam. The article presents results, including additional testing of nano materials. Additional tests were carried out to verify the purity and parameters of the investigated samples.