Vision and Fusion: Lecture 34 Vocabulary

Vocabulary and key concepts from Lecture 34 regarding nuclear fission, chain reactions, and nuclear fusion.

Fission

The process of artificially elongating and splitting an unstable atomic nucleus into two nuclei, which does not happen spontaneously and must be provoked.

Otto Hahn, Fritz Strassman, and Lise Meitner

The scientists who first observed nuclear fission in 1938.

Lise Meitner and Otto Frisch

The researchers who provided the theoretical explanation for the observations of nuclear fission.

$$E = mc^2$$

The equation used to quantify the energy created from the small amount of mass lost during the fission process, where $E$ is energy, $m$ is mass at rest, and $c$ is the speed of light.

Iron

The element situated between hydrogen and uranium that contains the least amount of mass per nucleon.

Uranium-235

A fissionable isotope of uranium that serves as the source for most nuclear power generated in the United States.

Byproducts of Uranium-235 Fission

The result of shooting a neutron at uranium-235, which includes Krypton-92, Barium-141, and three additional neutrons.

Chain Reaction

A self-sustaining reaction where the generation of new neutrons after each fission event kicks off further reactions without external intervention.

Critical Mass

The large enough quantity of fissionable material present that can result in a massive energy explosion, a principle used in nuclear weapons.

Subcritical Process

A nuclear process where, on average, less than one new fission reaction is generated per fission event, leading the reaction to stop over time.

Critical Reaction

A self-sustaining process where each fission event generates on average exactly one additional fission event.

Supercritical Reaction

A process where each fission event generates on average more than one additional fission event, leading to exponential growth in the number of reactions.

Control Rods

Components used in nuclear power plants to absorb excess neutrons and maintain a chain reaction at the critical stage.

Enrichment

The process of increasing the proportion of the fissionable isotope uranium-235 within a sample of mostly non-fissionable uranium-238.

Moderator

A substance used in a nuclear reactor to slow down neutrons until they reach the correct speed to cause fission in uranium-235.

Notable Nuclear Disasters

Historical examples of nuclear power plant failures, specifically Three Mile Island, Chernobyl, and Fukushima.

Nuclear Fusion

The process of smashing light atomic nuclei together (such as hydrogen into helium) to release energy, which occurs naturally in the sun.

Electromagnetic Repulsion

The force that prevents hydrogen atoms from coming together easily on Earth, requiring extraordinary speeds and temperatures to overcome for fusion.