Topic 11 - Nuclear Radiation

Topic 11

Activity

Number Of Nuclei That Decay Per Second, Measured In Becquerels (Bq).

Alpha Radiation

Radiation Of Particle Containing Two Protons And Two Neutrons.

Properties Of Alpha Radiation

Strongly Ionising, Slow Moving and Positively Charged, So Deflected By Magnetic Field.

Atomic Mass Unit

½ The Mass Of A Carbon-12 Nuclei.

Background Radiation

Constant Radiation Everywhere That Is Due To Radioactive Substances In The Environment.

Beta-Minus Radiation

Consists Of A High Energy Electron.

Properties Of Beta-Minus Radiation

Mildly Ionising, Fast Moving And Negatively Charged, So Deflected By Magnetic Field.

Beta-Plus Radiation

Consists Of A High Energy Positron.

Properties Of Beta-Plus Radiation

Mildly Ionising, Fast Moving And Positively Charged, Therefore Deflected By Magnetic Field, Opposite Direction To Beta-Minus Radiation.

Binding Energy

Energy Required To Split A Nucleus Into Its Individual Nucleons. The Greater The Bind Energy, The More Stable The Nucleus Is.

Chain Reaction

When The Fission Of One Nuclei Produces Neutrons That Cause Fission In Another Nuclei.

Control Rod

Rod Inserted Into Reaction Vessel That Stops Neutrons, Preventing Them From Continuing On To Cause More Fission Reactions. Made From Substances That Absorb Neutrons Without Fissioning Themselves.

Coolant

Fluid That Passes Around The Reaction Vessel And Carries Away Any Thermal Energy Produced By The Fission Reactions. This Thermal Energy Is Then Used To Generate Steam And Drive Generators To Produce Electricity.

Cooling Pond

Large Pool Of Water That Nuclear Waste Is Placed In To Allow It To Cool At Safe Temperatures.

Critical Mass

Minimum Amount Of A Fissile Substance Needed To Maintain A Chain Reaction And A Steady Flow Of Fission.

Decay Constant

Probability Of A Decay Occurring Per Unit Time.

Fuel Rod

Contains The Fissile Material. Each Rod Has Many Pellets Of Nuclear Fuel Which Prevents The Critical Mass Of Fuel Being Reached, Meaning The Reactions Are Controlled.

Gamma Radiation

Consists Of High Energy Photons.

Properties Of Gamma Radiation

Weakly Ionising, Travels At The Speed Of Light And Has No Charge, So Is Not Deflected By Magnetic Or Electric Fields.

Half Life (T½ )

Time Taken For Half Of The Radioactive Nuclei To Decay.

Moderator

Substance Inserted Between Nuclear Fuel That Reduces The Speed Of The Neutrons Coming From A Fission Reaction, Allowing Them To Become Thermal Neutrons That Can Induce Further Fission.

Nuclear Fission

Splitting Of A Large Nucleus To Produce Smaller Nuclei, Fast Moving Neutrons And Energy.

Nuclear Fusion

Fusing Of 2 Smaller Nuclei To Form A Single Nuclei Producing A Large Quantity Of Energy. Very High Temperatures And Pressures Are Required.

Nuclear Waste

By-Product Of A Nuclear Reaction. Waste Is No Longer Undergoing Fission That Can Be Used Due To The Reduced Activity, But The Waste Is Still Radioactive And Will Be For Thousands Of Years, So Stored Underground In Reinforced Containers.

Mass Defect

Difference Between The Mass Of Nuclei And Its Individual Components (Nucleons).

Spontaneous Fission

Process By Which A Nucleus Splits Without Absorbing A Thermal Neutron.

Thermal Neutron

Slow Moving Neutron That When Absorbed By And Unstable Nuclei Causes It To Undergo Fission.