Nuclear Radiation Flashcards
Learn about alpha, beta and gamma radiation, the effects of ionisation, absorption and shielding, background radiation, absorbed dose, equivalent dose, half life's, nuclear fission and fusion reactions, nuclear power, and biological effects if radiation
What are the 3 different types of radiation?
Alpha, Beta, and Gamma
What is an alpha particle?
An alpha particle is a nucleus of a helium atom
What is a beta particle?
A beta particle is a fast moving electron
What is gamma radiation?
Gamma radiation is a type of electromagnetic wave
What charge do alpha particles have?
They have a positive charge
What charge do beta particles have?
They have a negative charge
What charge do gamma rays have?
They don’t have a charge, as they are electromagnetic waves
What is larger - an alpha particle or a beta particle?
Alpha particles are larger
What speed do gamma rays travel at?
- 300,000,000 m/s
* 3x10^8
What can be used to absorb alpha radiation?
20cm of air or a thin sheet of paper
What can be used to absorb beta radiation?
3cm of aluminium
What can be used to absorb gamma radiation?
Several cm of lead or a few metres of concrete
Why are atoms usually neutral?
They have the same number of negative electrons as they do positive protons, which therefore give it no charge overall
What causes ions to be created?
When an electron is either attracted to or repelled from an atom, which causes the atom to become charged.
If an electron is lost, what charge will the ion have?
Positive charge
What is an ion?
A charged particle
What radiation causes the most ionisation?
Alpha radiation
Why do beta particles cause less ionisation?
They are smaller, so do less damage
Give the name and units for each letter in the equation -
A=N/t
A= Activity, Baqurels, Bq N= Number of decays, no unit t= Time, Seconds, S
In what 3 ways can controlled ionisation be beneficial?
Can be used to diagnose and treat certain illnesses
To protect people, such as smoke detectors
In industry, such as monitoring newspaper thickness in a paper mill
What is shielding?
When materials that absorb radiation are used to protect objects which are sensitive to the types radiation
What is absorbed dose?
Absorbed dose is how much energy per kilogram, from radiation, has been received
What is absorbed dose measured in?
Grays, Gy
Give the name and units of what each letter stands for in the equation-
D=E/m
D= Absorbed Dose, Grays, Gy E= Energy, Joules, J m= Mass, Kilograms, Kg
Give the name and units of what each letter stands for, in the equation -
H= WR x D
H= Equivalent Dose, Sievert, Sv D= Absorbed Dose, Grays, Gy WR= Radiation Weighting Factor, no units
What is background radiation?
Background radiation is radiation from our surroundings, which is normally at a very low level
What are some examples of natural sources of radiation?
Radon gas from rocks and soil
Gamma rays from the ground
Carbon and Potassium in our bodies
Cosmic rays from outer space
What are some artificial sources of radiation?
Medical applications, such as X rays and radionuclides
Fallout from weapons testing
Nuclear waste from power stations
How is radiation used in medical practices?
For xrays, scans and cancer treatments
What can radiation be used for in industry?
To test and inspect welds for flaws
What is equivalent dose measured in?
Sieverts, Sv
What is the definition of a half life?
The half life is the time taken for the activity of a radioactive source to fall to half of its previous value
What happens to a radioactive substance when it emits radiation?
Its nucleus decays
What is activity?
The rate of decay of an atoms nucleus
What happens in a fission reaction?
A nucleus with a large mass number splits, leaving 2 nuclei with smaller mass numbers, along with some neutrons
What are the 2 types of nuclear fission?
Spontaneous, and Induced
What type of fission occurs when there is an unstable nucleus?
Spontaneous Fission
How is Induced fission started?
Large atoms are forced to split, by bombarding them with with slow moving neutrons.
What is an example of a moderator, and what is it used for?
Graphite is a moderator which is used to slow down the fast moving neutrons released by a fission reaction. This increases the chances of further reactions happening.
What is a fission reaction managed by?
It’s managed by using a control rod, made of boron, to absorb some of the slow neutrons
How do uncontrolled fission reactions happen?
- a neutron enters the split nucleus
- from this, both energy and products are released
- this starts a chain reaction, which very quickly increases the number of nuclei involved
What is nuclear fusion?
Nuclear fusion is the joining of 2 or more smaller nuclei, to form a larger one
Where do fusion reactions take place?
In the sun and in other stars
In a nuclear power station, what is the heat released by the nuclear reaction used for?
To produce steam in the heat exchanger
What is the steam produced used for in a nuclear power station
To turn the turbine, which turns the generator to produce electricity
What biological effects does radiation have?
It can kill or damage living cells
If the DNA of a cell is altered it can grow into a tumour
What are some environmental hazards of radiation?
Very high doses can be fatal
Lower doses cause sickness and mutations
