PHY 1020: Chain Reactions, Nuclear Reactors, and Atomic Bombs

Vocabulary practice flashcards covering nuclear physics fundamentals, chain reactions, enrichment, atomic weapons of the Manhattan Project, nuclear reactor engineering, historical reactor incidents, radioactive waste disposal, and nuclear fusion technologies.

Chain reaction

A sequence of reactions where one event induces other subsequent events, exhibiting exponential behavior across nuclear, biological, and physical systems.

Law of doubling

A mathematical formulation describing exponential chain growth where products double at each step, expressed as $2^N$, where $N$ is the number of events.

Uranium enrichment

The industrial process of increasing the proportion of fissile uranium-235 by combining natural uranium with fluorine to produce uranium hexafluoride ($UF_6$) gas for extraction.

Critical mass

The smallest mass of fissile material needed to sustain a nuclear chain reaction, which is approximately $15\,kg$ for uranium and $5\,kg$ for plutonium.

Einstein-Szilard letter

An August 2, 1939 letter written by Leo Szilard and signed by Albert Einstein advising President Franklin D. Roosevelt of potential German nuclear research and advocating for American atomic development.

Manhattan Project

The United States research and development initiative formally established in June 1942 by the U.S. Army Corps of Engineers to produce the world's first operational nuclear weapons.

Trinity test

The world's first successful detonation of a nuclear device ('The Gadget'), conducted on July 16, 1945, near Socorro, New Mexico.

Little Boy

A $15\text{-kiloton}$ gun-type uranium-235 fission bomb dropped on Hiroshima on August 6, 1945, which achieved critical mass by firing a hollow uranium bullet into a target cylinder.

Fat Man

A $20\text{-kiloton}$ implosion-type plutonium-239 fission bomb dropped on Nagasaki on August 9, 1945, which attained critical mass through symmetrical explosive compression.

Thermonuclear weapon

A high-yield nuclear bomb (or 'Hydrogen Bomb') that utilizes radiation from a primary fission explosion to heat, compress, and ignite a secondary nuclear fusion stage.

Tzar Bomba

The largest Russian-tested thermonuclear weapon, yielding approximately $50\text{ megatons}$ with an estimated total blast radius of approximately $60\,km$.

Nuclear reactor

A facility designed to sustain a controlled, steady-state nuclear fission chain reaction using slow neutrons to produce thermal energy that boils water to turn turbines.

Moderator

A medium such as deuterated water or graphite installed in a reactor core to slow down fast fission neutrons through collisions so they can be captured to sustain fission.

Cherenkov radiation

The blue optical radiation emitted when charged particles such as electrons travel through an insulating medium (like water) at a velocity exceeding the phase velocity of light in that medium.

Three Mile Island incident

A 1977 reactor accident in Pennsylvania caused by cost cutting and a cooling clog that halted water circulation, causing cooling water to evaporate, exposing the core, and precipitating a partial meltdown.

Chernobyl disaster

A 1986 nuclear disaster in the Soviet Union resulting from testing operational limits; inserting graphite-tipped control rods displaced neutron-absorbing cooling water, prompting uncontrolled criticality and an explosion.

Fukushima Daiichi accident

A 2011 nuclear event initiated by a $9.0$ magnitude earthquake and tsunami that inundated backup generators, halting cooling and triggering hydrogen gas explosions across four reactor buildings.

Breeder reactor

A configuration of a fast reactor operating with surplus neutrons that generates more fissile material than it consumes, typically transmuting fertile uranium-238 into fissile plutonium-239.

Generation IV reactor

An advanced nuclear reactor design, exemplified by lead-cooled systems that utilize natural convection rather than active pumping to circulate coolant through the core.

Yucca Mountain

A proposed and active deep geologic repository in Nevada engineered for the safe, isolated storage of high-level radioactive nuclear waste.

Nuclear fusion

The reaction in which two light atomic nuclei collide and unite to form a heavier nucleus, releasing energy in stars like the Sun.

Tokamak

A toroidal magnetic confinement apparatus that utilizes helical magnetic fields to constrain high-temperature plasma for controlled thermonuclear fusion energy generation.

Inertial confinement fusion

A fusion approach utilizing high-energy laser pulses delivering tens of kilojoules of energy to rapidly heat, compress, and ignite a thermonuclear fuel target.

Muon-catalyzed fusion

A low-temperature fusion process in which negative muons replace atomic electrons to form muonic molecules ($dt\mu$), catalyzing deuterium-tritium fusion until about $1\%$ of muons stick to alpha particles.