Nuclear reactor physics is the physics of neutron fission chain reacting systems and this is the core discipline of the field of nuclear engineering. Nowadays nuclear reactor physics deals with the basic physical principles governing the behaviour of nuclear reactors which are well understood. Most of the basic nuclear data needed for nuclear reactor analysis have been measured and evaluated, and the computational methodology is highly developed and validated. It is now possible to accurately predict the physics behaviour of existing and future nuclear reactor systems under normal operating conditions. This course is designed to Introduce students to the range of concepts, ideas and models used in nuclear reactor physics. It was the best for further studying on nuclear theory of reactors, methods of experimental studies of neutron field, students' research work. The course is based on the classical course “Neutron transport theory” which has been taught at the National Research Nuclear University “MEPhI” during last 20 years. After studying the course, the student should be able to: define basic processes that may occur in the reactor core, laws, equations, and the limits of applicability of models describing the neutron field in the reactor; demonstrate the practical experience of calculating the distribution of neutrons in media; demonstrate the ability to analyze the process of slowing down neutrons in various media (typical for the nuclear fission reactors) from the standpoint of understanding the physics of the process; evaluate important reactor parameters including the performance and safety. You can find here some additional sources to discover information for best learning you can see here. Please pay attention to the first and last references, the material of the course is closer to them. The latter material is available in different languages. The learning of course material demands acquisition in math and general physics in accordance with 1st-2nd year of any technical bachelor education program. You need to be introduced to basics of integration, first and second order differential equations, vector algebra and mathematical analysis. You need to know the basics of atomic physics, but no special knowledge in nuclear and reactor physics is needed. Nuclear reactor physics is an application of nuclear physics which means that the behaviour of elementary particles and the nuclear energy is taken into consideration in this course. Nuclear energy comes either from spontaneous nuclei conversions or induced nuclei conversions. Conversions are associated with the mass and energy changes. By the modern data there are more than 100 elementary particles, most of them with anti-particles. The particles can be divided into two parts: particles without inner structure: fermions — quarks, leptons (the electron), bosons; and composite particles; hadrons – baryons (the proton, neutron), mesons. Since the proof of the atomic structure of nature in 1803 it was believed that atoms are the elementary particles. Discovery of the radiation indicated that there are subatomic particles. An atom is the smallest constituent unit of ordinary matter that has the properties of a chemical element. The following notation is used to define the nuclear reaction: Z — atomic number, the number of protons; N — neutron number, the number of neutrons; A – mass number of the Atomic nucleus, A = N + Z, the number of nucleons. The nucleus is a small, dense region consisting of protons and neutrons at the centre of the atom. The isotopes are variants of an atom with the different number of neutrons. The electron was discovered in 1897. The proton was discovered soon after the electron: the charge of a proton is the same in magnitude but opposite in sign to the charge of an electron. The neutron was discovered in 1932. The mass of a neutron is close to the mass of a proton. Two nuclear particles can interact together. As a result, two or more nuclear particles or γ-rays are produced. Nuclear particle can mean nucleus or nucleon. You can see the long and short formalism of description of the nuclear reaction, where a is the target in the rest before reaction and b is projectile. For example oxygen bombardment by energetic neutrons: it is sufficient to note four of the fundamental laws governing these reactions. Conservation of nucleons. The total number of nucleons before and after a reaction is the same. Conservation of charge. The sum of the charges of all the particles before and after a reaction is the same. Conservation of momentum. The total momentum of the interacting particles before and after a reaction is the same. Conservation of the energy. Energy, including the rest mass energy, is conserved in nuclear reactions. Nuclear physics required for nuclear reactors operates mostly with the nuclei and neutrons. Energy of individual reactions is small, therefore it is convenient to use a special energy unit — the electronvolts. The atomic scale mass is expressed by the atomic mass unit — a. m. u. It is by definition 1/12 (one twelfth) of the rest mass of an unbound atom of carbon 12. Avogadro number expresses the number of elementary entities per 1 mole of a substance. We need to know the quantity of nuclei in the medium. For definition of the Quantities Describing Material Properties we uses: Atomic Mass is the mass of a specific isotope. It can be expressed relatively in the atomic mass units. Mass Weight is an average mass of atoms of an element expressed in a. m. u. Molar Mass is the mass of one mole of a substance. It is important to determine the quantity of atoms or nuclei per volume unit (designated as N). And by definition we need the weight density of a substance multiplied by the Avogadro number and divided by the molar mass of the molecule of a substance.