Physics Concepts And Connections Chapter 15

Front 1

Nuclear Fusion

Back 1

A nuclear reaction in which two nuclei combine to form a single, larger nucleus. Nuclear energy is released whenever two light nuclei are fused to create a nucleus that is lighter than iron.

Front 2

Nuclear Fission

Back 2

A nuclear reaction in which a large, single nucleus splits into two roughly equal smaller nuclei. Nuclear energy is released whenever a heavy nucleus is fissioned into two nuclei that are both heavier than iron.

Front 3

Nuclear Energy

Back 3

The energy resulting from the structure of a material's nuclei. It is energy due to nuclear structure.

Front 4

Release of Nuclear Energy

Back 4

Any transformation of nuclear energy into other forms of energy.

Front 5

Thermonuclear Reaction

Back 5

A self-sustaining fusion reaction that creates the thermal energy needed to sustain itself.

Front 6

Nuclear Energy Curve

Back 6

A graph showing the energies of the different nuclei versus their mass number. The graph shows a lowest point at mass number 56 (iron), indicating that nuclear energy can be released by the fusion of nuclei lighter than iron and by the fission of nuclei heavier than iron.

Front 7

Big Bang

Back 7

The event some 14 billion years ago that created time, space, matter, and the different forms of energy, and started the expansion of the universe.

Front 8

Supernova Explosion

Back 8

The explosion of a giant star. Supernovae spread the chemical elements into space and so are the source of the elements heavier than helium in our solar system.

Front 9

Fission Fragments

Back 9

One of the two pieces that results from the fissioning of a nucleus.

Front 10

Chain Reaction

Back 10

A series of neutron-induced fission reactions that proceed from one nucleus to the next by means of the neutrons released during each fission reaction.

Front 11

Manhattan Project

Back 11

The U.S. project during World War II to build fission bombs.

Front 12

Fission Bomb (atomic bomb "A-bomb")

Back 12

A bomb that gets its energy from a fission chain reaction. The fuel can be either the uranium isotope U-235 or plutonium. In the U-235 bomb, the design can be as simple as bringing two subcritical masses together to equal or exceed a critical mass. If the bomb contains plutonium, a subcritical mass is made critical by squeezing it to high density.

Front 13

Nuclear Power Reactor

Back 13

A device in which chain-reacting nuclei transform nuclear energy into thermal energy for electric power. Its main components are fuel to provide energy, neutron-absorbing control rods to control the reaction, and a coolant to transfer thermal energy from the fuel. Most reactors are enclosed in a thick, concrete containment dome to prevent the escape of radioactivity into the environment.

Front 14

Proliferation of Nuclear Weapons

Back 14

The spread of nuclear weapons to additional nation and to terrorists.

Front 15

Isotope Separation, (enrichment, of uranium)

Back 15

Any process that increases the percentage of U-235 relative to U-238. One method is by use of spinning centrifuges. Weapons-grade uranium is highly enriched to about 90% U-235.

Front 16

Centrifuge Separation

Back 16

One way, widely used today, to enrich uranium.

Front 17

Uranium Enrichment

Back 17

The process of increasing the proportion of U-235 to U-238 in natural uranium.

Front 18

Highly Enriched Uranium

Back 18

Uranium that has been enriched to about 90% U-235, which is suitable for nuclear weapons use.

Front 19

Critical Mass

Back 19

The minimum amount of fissionable material that will sustain a chain reaction.

Front 20

Technological Imperative

Back 20

The tendency to build whatever technology is possible.

Front 21

Technological Momentum

Back 21

The tendency to continue a technological project once it is started.

Front 22

Kiloton

Back 22

The amount of energy that would be released in the explosion of one thousand tons of TNT.

Front 23

Hiroshima and Nagasaki

Back 23

The Japanese cities that were fission-bombed near the end of World War II.

Front 24

Fusion Bomb (hydrogen bomb)

Back 24

A bomb that gets its energy from the fusion of hydrogen, triggered by a fission bomb.

Front 25

Megaton

Back 25

The amount of energy that would be released in the explosion of one million tons of TNT.

Front 26

Action-Reaction Cycle

Back 26

A mutually reinforcing cycle of increased armaments by two or more hostile nations.

Front 27

Weapons of Mass Destruction

Back 27

Nuclear, chemical, or biological weapons.

Front 28

Dirty Bomb

Back 28

A bomb powered with conventional explosions that does damage primarily by the dispersal of radioactive materials. One of the possible forms of nuclear terrorism.