Nuclear Radiation Flashcards
What is the activity of a radioactive source measured in?
Becquerels (Bq)
Activity is defined as the number of nuclei that decay per second.
What particles make up alpha radiation?
Two protons and two neutrons
Alpha radiation is strongly ionising, slow moving, and positively charged.
Define Atomic Mass Unit (AMU).
1/12 the mass of a Carbon-12 nuclei
AMU is a standard unit of mass that quantifies mass on an atomic or molecular scale.
What is background radiation?
Constant radiation due to radioactive substances in the environment
It is present everywhere and comes from natural and artificial sources.
Describe beta-minus radiation.
High energy electron that is mildly ionising, fast moving, and negatively charged
It is deflected by a magnetic field.
What characterizes beta-plus radiation?
High energy positron that is mildly ionising, fast moving, and positively charged
It is deflected by a magnetic field in the opposite direction to beta-minus radiation.
What is binding energy?
The energy required to split a nucleus into its individual nucleons
Greater binding energy per nucleon indicates a more stable nucleus.
What is a chain reaction in nuclear physics?
When neutrons produced in fission of one nucleus causes the fission of another nucleus
It is a self-sustaining series of reactions which is not controlled can lead to a meltdown.
What is the purpose of a control rod in a nuclear reactor?
To stop neutrons from causing further fission reactions
Control rods are made from materials that absorb neutrons without undergoing fission themselves.
What does a coolant do in a nuclear reactor?
Carries away thermal energy produced by fission reactions
This thermal energy is used to generate steam and produce electricity.
What is critical mass?
The minimum amount of a fissile substance needed to maintain a chain reaction
It ensures a steady flow of fission events.
Define decay constant.
The probability of a decay occurring per unit time
It is a key parameter in radioactive decay processes.
What is contained within a fuel rod?
Fissile material in pellets
Fuel rods help control the critical mass of nuclear fuel.
Describe gamma radiation.
High energy photons, weakly ionising, travels at the speed of light
Gamma radiation has no charge and is not deflected by magnetic or electric fields.
What is half-life (T 1/2)?
The time taken for half of the radioactive nuclei to decay
It is a measure of the stability of a radioactive isotope.
What is a moderator in a nuclear reactor?
A substance that reduces the speed of neutrons
This allows neutrons to become thermal neutrons that can induce further fission.
Define nuclear fission.
The splitting of a large nucleus to produce smaller nuclei, fast moving neutrons, and energy
It is a key process in nuclear reactors.
What is nuclear fusion?
The fusing of two smaller nuclei to form a single nucleus
This process produces a large quantity of energy and requires very high temperatures and pressures.
What is nuclear waste?
The by-product of a nuclear reaction that is still radioactive
It must be stored underground in reinforced containers for thousands of years.
What is mass defect?
The difference between the mass of the nucleus and its individual components
It relates to energy release during fission or fusion.
What is spontaneous fission?
The process by which a nucleus splits without absorbing a thermal neutron
It occurs naturally in certain isotopes.
What is a thermal neutron?
A slow moving neutron that can induce fission in unstable nuclei
Thermal neutrons are crucial for sustaining chain reactions in nuclear reactors.
