Nuclear Chemistry – Fission, Fusion, Reactors & Radiation

Vocabulary flashcards covering core terms from the lecture on nuclear fission, fusion, reactor design, energy calculations, and radiation biology.

Nuclear fission

The splitting of a heavy nucleus (e.g., U-235) into lighter nuclei with release of energy and neutrons.

Chain reaction (nuclear)

A self-sustaining series of fission events in which neutrons from one split nucleus trigger additional fissions.

Uranium-235

The fissile isotope of uranium commonly used as fuel in nuclear bombs and reactors.

Neutron multiplication

Process where one incoming neutron causes fission that emits ~3 new neutrons, leading to exponential growth of reactions.

Fuel rod

Rod-shaped assemblies containing enriched U-235 that supply fissionable material inside a reactor core.

Control rod

Neutron-absorbing rod (often boron or cadmium) inserted into a reactor core to regulate the rate of fission.

Boron

Element commonly used in control rods because of its strong neutron-absorbing ability.

Cadmium

Metal used in control rods to capture excess neutrons and prevent runaway reactions.

Nuclear reactor

Engineered system that controls fission to generate steady heat for electricity production.

Steam turbine

Device turned by high-pressure steam from boiled reactor water to generate electricity.

Mass defect

The small mass difference between reactants and products in a nuclear reaction, converted to energy.

E = mc²

Einstein’s equation showing that lost mass (m) becomes energy (E); c is the speed of light.

Joule

SI unit of energy; one mole of U-235 fission releases ~1.7 × 10¹³ J.

Exothermic chemical reaction

Reaction releasing heat; even the most exothermic chemical processes (~10⁶ J/mol) are far weaker than fission.

Meltdown

Severe reactor accident where uncontrolled fission overheats fuel, potentially breaching containment.

Nuclear fusion

Combining two light nuclei (e.g., tritium + deuterium) into a heavier nucleus with enormous energy release.

Tritium (³H)

Radioactive hydrogen isotope (one proton, two neutrons) used in fusion reactions.

Deuterium (²H)

Stable hydrogen isotope (one proton, one neutron) that can fuse with tritium to form helium.

Helium-4

Stable nucleus produced during T–D fusion, accompanied by one free neutron.

High-temperature plasma

State of matter required to overcome repulsive forces in fusion; achieved in stars and experimental reactors.

Sun (stellar fusion)

Natural fusion reactor where hydrogen nuclei fuse, powering solar radiation that reaches Earth.

Ionizing radiation

High-energy particles or waves capable of knocking electrons out of atoms and molecules.

Radical (free radical)

Highly reactive molecule with an unpaired electron, often formed when radiation breaks chemical bonds.

Acute radiation effects

Immediate biological damage from high radiation doses, including cell death and tissue malfunction.

Cancer risk (radiation)

Increased likelihood of uncontrolled cell growth due to DNA mutations caused by ionizing radiation.

Genetic effects of radiation

Heritable defects arising when radiation alters DNA in reproductive cells or developing embryos.

Enriched uranium

Uranium processed to raise its U-235 content, making it suitable for reactor fuel or weapons.

Critical mass

Minimum amount of fissile material needed to sustain a chain reaction.

Plutonium-239

Artificially produced fissile isotope used as alternative fuel or in nuclear weapons.

Electricity from nuclear power

Accounts for roughly 20 % of U.S. electricity generation, with potential to grow as energy demand rises.