Key Points: 8. Nuclear Physics: Paper 2: Physics A Level AQA

In the early days (1803) Dalton thought that everything was made up of __________________.

indivisible particles

Beta-minus

Beta-minus radiation consists of an electron and Beta-plus radiation consists of a positron.

Activity

The number of nuclei that decay per second, measured in Becquerels.

Half-Life

The time it takes for the number of radioactive nuclei to halve, for a given isotope.

Decay Constant

The probability of a decay occurring in a unit time.

Spontaneous fission

Spontaneous fission is rare, a fissile nuclei normally need to absorb a thermal neutron to induce fission.

Thermal neutron

A thermal neutron is a slow moving neutron that can induce fission.

Control rods

Control rods absorb neutrons to prevent them going on to induce further fission - the lower the rods are inserted, the more neutrons that are absorbed and so the fewer the number of fission reactions that occur.

Moderator

The moderator is responsible for slowing down the neutrons released in fission reactions so that they are at the speed of a thermal neutron and can go on to induce further fission.

Fuel rods

Fuel rods consist of a fissile material - each rod contains less than the critical mass so that the reactions don’t become uncontrolled.

Coolant

Coolant carries away the thermal energy produced by fission reactions to generate steam and turn generators

Binding Energy

Binding Energy is the energy required to split up the nucleus into its individual nucleons. The greater the binding energy per nucleon the more stable the nucleus.

Mass Defect

Mass Defect is the difference between the mass of the nucleus and its individual constituents.

Atomic Mass Unit

The Atomic Mass Unit is the average mass of a nucleon, 1/12 the mass of Carbon-12.

E = mc²