Radioactivity , Half Life , Decay Flashcards
What is an isotope?
Atoms of the same element with different numbers if neutrons. The isotopes of an element have the same number of protons.
What are the three main types of ionising radiation?
Alpha, Beta and Gamma
Describe and explain Alpha radiation
- 2 neutrons, 2 protons (helium neclei)
- +2 electric charge
- Relative atomic mass of 4
- Strongly ionising
Describe and explain Beta radiation
- High energy electron
- -1 electric charge
- 1/1860th automic mass
- Weakly ionising
Describe and explain Gamma radiation
- High electromagnetic radiation
- 0 electric charge
- 0 relative automic mass
- Very weakly ionising
How is low level nuclear waste disposed of?
In drums surrounded by concrete, and in clay lined landfill sites
How is intermediate levels of nuclear waste disposed of?
Mixed with concrete and put in a stainless steel drum in a purpose built store
How is high level nuclear waste disposed of?
Stored underwater for 20 years, then placed in storage casks in purpose built underground stores. This can decay over many thousands of years
What is background radiation?
Radiation that can come from the environment:
- cosmic rays
- rocks and soil
- living things
Or artifically:
- X rays
- Waste from power stations
- Nuclear fallouts
Define half life
The time it takes for the charge, mass or nuclei to halve
What stops alpha radiation?
Alpha radiation is the least penetrating. It can be stopped (or absorbed) by a human hand.
What stops beta radiation?
Beta radiation can penetrate air and paper. It can be stopped by a thin sheet of aluminium.
What stops gamma radiation?
Gamma radiation is the most penetrating. Even small levels can penetrate air, paper or thin metal. Higher levels can only be stopped by many centimetres of lead or many metres of concrete
How do control/absorption rods control a nuclear reaction?
The control rods are neutron-absorbing rods, which are inserted into the spaces between the fuel rods, and are made from materials such as boron.
The control rods can be moved down into the reactor, which slows the reaction down by absorbing more of the neutrons, or moved up so that fewer of the neutrons are absorbed, which means that the reaction remains constant and explosions do not occur.
The nuclear fuel rods in a reactor can be radioactive for a very long time and have to be stored very carefully.
What is fission?
The splitting of an atom into two (three neutrons produced). Where a slow moving neutron, hits a nuclei, makes it unbalanced, splits.
