Nuclear Fission: Basics and Chain Reaction

This lecture covers the basic principles of nuclear fission, starting with the collision between a neutron and a uranium nucleus, leading to either scattering or absorption. The process of nuclear fission involves the absorption of a neutron by uranium 235, resulting in the formation of uranium 236 which then breaks down into different particles, releasing energy in the form of gamma and beta rays. The lecture explains how a chain reaction occurs, with the generation of more neutrons leading to the production of additional energy. The concept of critical and supercritical cases in nuclear reactions is also discussed, emphasizing the importance of controlling reactivity to prevent overheating.

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related lectures (36)

Related concepts (39)

ME-409: Energy conversion and renewable energy

This course presents an overview of (i) the current energy system and uses (ii) the main principles of conventional and renewable energy technologies and (iii) the most important parameters that defin

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.

In nuclear physics, a nuclear chain reaction occurs when one single nuclear reaction causes an average of one or more subsequent nuclear reactions, thus leading to the possibility of a self-propagating series of these reactions. The specific nuclear reaction may be the fission of heavy isotopes (e.g., uranium-235, 235U). A nuclear chain reaction releases several million times more energy per reaction than any chemical reaction.

A gamma ray, also known as gamma radiation (symbol γ or ), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically shorter than those of X-rays. With frequencies above 30 exahertz (3e19Hz), it imparts the highest photon energy. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium.

Uranium-235 (235U or U-235) is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile isotope that exists in nature as a primordial nuclide. Uranium-235 has a half-life of 703.8 million years. It was discovered in 1935 by Arthur Jeffrey Dempster. Its fission cross section for slow thermal neutrons is about 584.3±1 barns. For fast neutrons it is on the order of 1 barn.

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.

Introduction to Nuclear Engineering ME-464: Introduction to nuclear engineering

Introduces nuclear engineering, covering reactions, chain reactions, fuel cycle, criticality, and multiplication factors.

Introduction to Nuclear Engineering: Gen IV Reactors ME-464: Introduction to nuclear engineering

Introduces Generation IV nuclear reactors, focusing on fast-spectrum reactors and their sustainability, breeding of fissile fuel, properties of coolants, historical development, advantages, disadvantages, and key challenges.

Reactor Technology: Reactivity Variations and Control PHYS-443: Physics of nuclear reactors

Explores reactivity variations in reactor technology, covering short-term, medium-term, and long-term effects, means of control, and consequences.

Introduction to Nuclear Engineering: Chain Reactions and Fuel Cycles ME-464: Introduction to nuclear engineering

Explores chain reactions, criticality, reactor types, and fuel cycles in nuclear engineering.

Nuclear Fission: Energy Release and Neutron Interactions PHYS-443: Physics of nuclear reactors

Explores nuclear fission, energy release, fission neutrons, and practical fuels in a nuclear reactor.