Fission, Fusion, and Nuclear Decay - AP Physics 2

What particle is emitted during alpha decay?

An alpha particle, which consists of 2 protons and 2 neutrons. Equivalent to a helium nucleus ( $^4He$ ).
Which element is commonly used in nuclear weapons?

Plutonium-239 or Uranium-235. Both are fissile materials capable of sustaining chain reactions.
What is nuclear fission?

Nuclear fission is the splitting of a heavy nucleus into lighter nuclei. This releases energy due to the mass difference.
What is a neutron moderator in a nuclear reactor?

A material that slows down neutrons to sustain a chain reaction. Thermal neutrons have higher fission probability than fast neutrons.
Identify a common isotope used in nuclear fission reactors.

Uranium-235. Fissile isotope that absorbs thermal neutrons effectively.
What is the role of control rods in a nuclear reactor?

To absorb excess neutrons and regulate the fission reaction. Insertion/withdrawal controls reaction rate and reactor power.
What is the role of a breeder reactor?

To generate more fissile material than it consumes. Converts fertile material into fissile fuel through neutron capture.
What is the meaning of critical mass?

The minimum amount of fissile material needed to sustain a chain reaction. Below this threshold, chain reaction cannot be sustained.
What is a tokamak?

A device used to confine plasma for nuclear fusion using magnetic fields. Magnetic confinement system for controlled fusion research.
What is the result of a nuclear fusion reaction between deuterium and tritium?

Helium and a neutron. $^2H + ^3H \rightarrow ^4He + n$ releases 17.6 MeV.
State the equation for mass-energy equivalence.

$E = mc^2$ . Einstein's equation relating mass and energy equivalence.
What is the main source of energy in a nuclear fission reaction?

The binding energy released when a nucleus splits. Mass defect converts to kinetic energy of fission fragments.
What is a radioisotope?

An isotope that is radioactive. Unstable nucleus that spontaneously undergoes radioactive decay.
What is the primary challenge of achieving nuclear fusion on Earth?

Maintaining the necessary high temperature and pressure. Plasma confinement requires millions of degrees temperature.
How does beta decay affect the atomic number of an element?

Increases by 1 if it's beta-minus decay; decreases by 1 if it's beta-plus decay. Neutron converts to proton (β⁻) or proton to neutron (β⁺).
What is the main advantage of nuclear fusion over fission?

Fusion produces less radioactive waste. Fusion products are generally stable or short-lived.
Identify the main fuel used in nuclear fusion reactions.

Hydrogen isotopes, typically deuterium and tritium. Light nuclei overcome strong nuclear force barriers when fused.
What is the primary product of nuclear fusion in stars?

Helium. Formed when hydrogen nuclei undergo fusion reactions.
Which isotope is used in radiocarbon dating?

Carbon-14. Decays with 5,730-year half-life for age determination.
What is the primary purpose of a nuclear reactor's containment structure?

To prevent the release of radioactive materials. Concrete and steel barrier for radiation shielding.
Define nuclear decay.

Nuclear decay is the process by which an unstable atomic nucleus loses energy. This occurs through alpha, beta, or gamma emission.
What is emitted during gamma decay?

Gamma rays, which are high-energy photons. No change in mass or atomic number, only energy release.
What is tritium?

A radioactive isotope of hydrogen. Contains one proton, two neutrons, and is unstable.
What is the function of a cooling system in a nuclear reactor?

To remove heat from the reactor core. Prevents meltdown by transferring heat to steam generators.
Name a common use of gamma radiation outside of nuclear decay.

Sterilization of medical equipment. High-energy photons kill bacteria and viruses effectively.
What is nuclear fusion?

Nuclear fusion is the process of combining light nuclei to form a heavier nucleus. This requires extremely high temperatures to overcome electrostatic repulsion.
Identify the three types of nuclear decay.

Alpha decay, beta decay, gamma decay. These differ in particles emitted and penetrating power.
Identify the force that must be overcome for fusion to occur.

Electrostatic repulsion between nuclei. Coulomb barrier requires high kinetic energy to overcome.
What is the main disadvantage of nuclear fission as an energy source?

Generation of long-lived radioactive waste. Waste remains dangerous for thousands of years.
What is the typical unit for measuring radiation dose?

Sievert (Sv). Measures biological effect of radiation on human tissue.
What is a chain reaction in nuclear fission?

A series of nuclear fissions, each initiated by a neutron from the previous fission. Self-sustaining reaction requires critical mass to maintain.
Name a gas commonly used in nuclear fusion research.

Deuterium or tritium. Heavy hydrogen isotopes have lower Coulomb barriers.
What is a common application of alpha particles?

Smoke detectors. Alpha particles ionize air to detect smoke particles.
Define half-life in the context of nuclear decay.

The time required for half of the radioactive nuclei in a sample to decay. Exponential decay follows first-order kinetics.
Which element is commonly used as a neutron moderator?

Graphite or heavy water (D $_2$ O). Both effectively slow down fast neutrons to thermal energies.
Which nuclear process powers the Sun?

Nuclear fusion. Hydrogen nuclei fuse to form helium in the Sun's core.
How is nuclear decay used in medical imaging?

Radioisotopes are used in PET scans. Radioisotopes emit gamma rays detectable by imaging equipment.
Identify a safety concern associated with nuclear fusion.

Containment of high-temperature plasma. Plasma instabilities can damage reactor components.
What particle is emitted during beta decay?

A beta particle, which is an electron or positron. Occurs when neutron converts to proton or proton to neutron.

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