Lecture

Neutron Moderation

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In course

PHYS-443: Physics of nuclear reactors

In this course, one acquires an understanding of the basic neutronics interactions occurring in a nuclear fission reactor as well as the conditions for establishing and controlling a nuclear chain reaction. ...

Description

This lecture covers the concepts of slowing down equations, lethargy, and Fermi age theory in the context of neutron moderation. It discusses the interaction of neutrons with matter, nuclear fission, simplified modeling of multiplying media, and the diffusion of neutrons. The lecture also explores neutron kinetics, reactor technology, and the Fermi age theory for neutron balance in a volume. The physical significance of Fermi age and space-dependent slowing down are explained, along with the relationship between neutron migration and distance from the source.

Instructors (3)

Mathieu Hursin

Current work I'm currently heavily involved in the nuclear data community and with technical work towards the improvement of the latest version of the European library (JEFF). I'm leading an OECD/NEA subgroup in that direction. I'm also leading a Euratom project towards the production of multi-physics experimental data suitable for the validation of high-fidelity, high-resolution simulation tools. After a doctoral thesis on the high-fidelity modeling of control rod ejection in a pressurized water reactor at

Carlo Fiorina

Andreas Pautz

Teaching & PhD PhD Students Sofia Portolan, Michel Saliba, Bishal Torrente, Alexis Paul Boris Claude Dupont-Bembinoff, Cynthia Camila Güttlein Past EPFL PhD Students Ting Zhu, Vladimir Vladimirov Brankov, Boris Aviv Hombourger, Damar Canggih Wicaksono, Petra Mala, Adolfo Rais, Valentyn Bykov, Daniel Jerôme Siefman, Evgeny Nikitin, Dionysios Chionis, Oskari Ville Pakari, Friederike Bostelmann, Jiani Gao, Efstathios Vlassopoulos, Alessandro Scolaro, Stefan Radman, Alexander Aures, Lubomír Bures, Ahmed Salah

Official source

Ontological neighbourhood

Energy engineering

Nuclear power: Topics in nuclear power

Related concepts (32)

Nuclear reactor

A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from nuclear fission is passed to a working fluid (water or gas), which in turn runs through steam turbines. These either drive a ship's propellers or turn electrical generators' shafts. Nuclear generated steam in principle can be used for industrial process heat or for district heating.

Thermal-neutron reactor

A thermal-neutron reactor is a nuclear reactor that uses slow or thermal neutrons. ("Thermal" does not mean hot in an absolute sense, but means in thermal equilibrium with the medium it is interacting with, the reactor's fuel, moderator and structure, which is much lower energy than the fast neutrons initially produced by fission.) Most nuclear power plant reactors are thermal reactors and use a neutron moderator to slow neutrons until they approach the average kinetic energy of the surrounding particles, that is, to reduce the speed of the neutrons to low-velocity, thermal neutrons.

Breeder reactor

A breeder reactor is a nuclear reactor that generates more fissile material than it consumes. These reactors can be fuelled with more commonly available isotopes of uranium and thorium, such as uranium-238 or thorium-232, as opposed to the rare uranium-235 which is used in conventional reactors. These materials are called fertile materials since they can be bred into fuel by these breeder reactors. Breeder reactors achieve this because their neutron economy is high enough to create more fissile fuel than they use.

Generation IV reactor

Generation IV reactors (Gen IV) are nuclear reactor design technologies that are envisioned as successors of generation III reactors. The Generation IV International Forum (GIF) - an international organization that coordinates the development of generation IV reactors - specifically selected six reactor technologies as candidates for generation IV reactors. The designs target improved safety, sustainability, efficiency, and cost.

Neutron temperature

The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term temperature is used, since hot, thermal and cold neutrons are moderated in a medium with a certain temperature. The neutron energy distribution is then adapted to the Maxwell distribution known for thermal motion. Qualitatively, the higher the temperature, the higher the kinetic energy of the free neutrons. The momentum and wavelength of the neutron are related through the de Broglie relation.

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