Radiation Flashcards
DESCRIBE THE MODEL OF AN ATOM
- In an uncharged atom, the number of protons in the nucleus are even to the number of electrons orbiting the nucleus.
- The nucleus contains protons and neutrons.
- Electrons, negative.
Protons, positive
Neutrons, neutral
DESCRIBE ALPHA RADIATION
An alpha particle is a helium nucleus (two protons and two neutrons) with a positive charge. It is large in size compared to beta.
DESCRIBE BETA RADIATION
A beta particle is a high speed electron (produces within the nucleus) and is negative. It is small compared to alpha.
DESCRIBE GAMMA RADIATION
Gamma radiation is a high frequency, high energy electromagnetic wave. It travels at the speed of light.
HOW DOES A RADIOACTIVE MATERIAL BECOME STABLE
A radioactive material is made up of atoms with unstable nuclei. They become stable when the nucleus decays and emits alpha, beta or gamma.
DESCRIBE IONISATION
Ionisation is when an electron is added to an atom or lost from an atom making it charged. What is left is called an ion. Alpha is most ionising and gamma is least ionising.
HOW DOES RADIATION KILL LIVING CELLS
When living tissue receives a dose of radiation, ionisation takes place which can disrupt the way the cells operate.
HOW DOES A GEIGER MULLER TUBE WORK
The tube detects gas. The ions in the gas produce a current in the tube for a short time. This current produces voltage pulses and the voltage pulses are measured on the counter.
WHAT IS EACH RADIATION ABSORBED BY
- Alpha radiation is absorbed by a piece of paper or a few cm of air
- Beta is absorbed by a few mm of aluminium or a few m of air.
- Gamma is absorbed by a few cm of lead or a few km of air.
WHAT IS ACTIVITY
The number of radioactive decays per second (Bequerells)
WHAT IS BACKGROUND RADIATION
Background radiation is radiation from our surroundings and is normally at a low level.
WHAT ARE NATURAL SOURCES OF RADIATION
Radon gas from rocks, Gamma rays from the ground, Cosmic rays from space.
WHAT ARE ARTIFICIAL SOURCES OF RADIATION
Medical applications such as tracers, fallout from weapon testing, nuclear waste from power stations.
MEDICAL APPLICATIONS OF RADIATION
Radiotherapy, x-rays, tracers
INDUSTRIAL APPLICATIONS
Testing welds
WHAT JOBS ARE EXPOSED TO RADIATION EACH YEAR
Miners, nuclear power plant workers and aircrew are exposed to large doses of radiation each year
WHAT IS ABSORBED DOSE
The absorbed dose is the energy absorbed per unit mass of the absorbing material (Grays)
WHAT IS THE EQUIVALENT DOSE
The equivalent dose is the measure of biological harm caused by the radiation
WHAT IS THE RADIATION WEIGHTING FACTOR
The measure of biological effect of a radiation
WHAT IS THE EQUIVALENT DOSE RATE
The equivalent dose per unit time
THREE RANDOM PIECES OF INFORMATION
- Average annual background radiation in the UK is 2.2mSv.
- Annual effective dose limit for members of the public is 1mSv.
- Annual effective dose limit for a radiation worker is 20mSv.
WHAT ARE THREE WAYS TO PROTECT YOURSELF FROM RADIATION
Shielding, limit time of exposure, distance from source
WHAT ARE APPLICATIONS OF ALL THREE TYPES OF RADIATION
Gamma rays - radio therapy.
Beta - measuring the thickness of materials.
Alpha - smoke detectors.
WHAT IS THE HALF LIFE OF A SOURCE
The half life is the time taken for a radioactive sources activity to drop to half its previous value. (The activity of any radioactive source decreases with time).
WHAT IS THE HALF LIFE EXPERIMENT
- Use a stop clock and counter to measure the amount of counts in one minute.
- Repeat this ten minutes later.
- Repeat every ten minutes for two hours.
- Measure the background radiation and deduct it from the values.
- Plot the results on a graph and measure the half life.
WHAT IS FISSION ( SPONTANEOUS AND INDUCED)
Fission is when a heavy nuclear disintegrates leaving two nuclei of smaller mass and some neutrons.
Spontaneous fission - Nucleus is unstable.
Induced fission - reaction is started when a fast moving neutron collided with a Uranium nucleus, making is unstable (nuclear power stations).
WHATS A CHAIN REACTION (UNCONTROLLED FISSION REACTION)
When the neutrons released go on to create other fission reactions. If a reaction isn’t kept under control, it can make a bomb
BENEFIT AND PROBLEM OF USING FISSION TO PRODUCE ENERGY
Nuclear power stations can produce large amounts of energy with small amounts of fuel using nuclear fuel but nuclear waste must be stored securely for a long time.
WHAT IS FUSION AND WHERE DOES IT TAKE PLACE
when two or more nuclei combine to form an element with a higher mass number.
Fusion takes place in the sun and stars.
PLASMA CONTAINMENTS (PROBLEMS WITH FUSION TO GENERATE ENERGY)
For fusion to take place, atoms must be heated to temperatures around 40 000 000 Kelvin to be pressurised enough for fusion to occur. When atoms are heated to such heats, they become a different state of matter called plasma. Containing plasma can only be done with strong magnetic field and is very difficult and expensive.
WHAT DOES THE BIOLOGICAL EFFECTS OF RADIATION DEPEND ON
The risk of biological harm from radiation depends on the type of radiation, the type of tissue, the absorbed dose.
WHAT ARE THE ENVIRONMENTAL HAZARDS OF RADIATION
High doses of radiation can be fatal to plants, humans and animals. Low doses can cause sickness and mutations.
6 SAFETY PROCEDURES
- Always use forceps to handle a source, never bare hands.
- Always arrange the source so that its radiation window faces away from the body.
- Never bring a radioactive source close to your eyes to identify, always identify by a colour or number.
- A source must always be attended to by an authorised person and must be returned to a lead lined box.
- Always wash your hands after any experiment with a radioactive material.
- The warning sign must always be displayed whenever radioactive sources are stored.
WHAT IS THE RADIATION WARNING SIGN
three way gas sign in a triangle
