P6.2 Flashcards
What is contamination?
Happens when you take radioactive material inside your body or if it is on your skin
Once internally contaminated you cannot remove the radioactive material
Can damage DNA inside your cells, cause cancer
What is irradiation?
Happens when there is no radioactive material outside your body but the radiation can travel into your body
Can damage DNA inside your cells, cause cancer
What is the risk of getting cancer from radiation?
Low if not exposed to much radiation as body can repair small damage to DNA
When do you take radioactive material?
Doctors may inject you with a radioactive isotope that is absorbed by the organs of your body
The isotope is detected by a gamma camera
The camera makes images of your organs which helps doctors diagnose disease
What type of radioactive isotope would radiographers choose?
- half life cannot be too short as the tracer would decay before they can use the gamma camera
- if half life is too long then tracer will continue to emit radiation for too long, increases risk of cancer
How are gamma rays used in medicine?
Can be used to treat cancer
Radiation can damage the cancer cells to restrict their growth or kill them
Gamma knife - focuses gamma rays on a cancer tumour, need to be careful not dose the healthy tissue
What is nuclear fission?
When a large nucleus splits into fragments and emits neutrons
Doesn’t happen spontaneously
When is nuclear fission likely to occur and how?
If a nucleus absorbs a neutron
Nucleus splits and produces two smaller nuclei and two or three neutrons
The smaller nuclei may be unstable and decay
How does a nuclear power station use nuclear fission?
- to heat water to produce steam to drive turbines and generators
- to power a nuclear submarine or spacecraft
What is a chain reaction?
The neutrons released from a nuclear fission can trigger other fission reactions
Can only occur if there are enough nuclei around the first nuclei
How are chain reactions controlled in a nuclear power station?
By using materials to absorb one of the neutrons
In a nuclear bomb none of the neutrons are absorbed so a huge amount of energy is released
What is nuclear fusion?
Large nuclei split and eventually form stable elements
Lighter nuclei can join together to make more stable nuclei which is nuclear fusion
What are the conditions in the sun that allow fusion reactions?
- high temperatures, nuclei are moving at high speeds
- high pressured, which keep the nuclei close enough to fuse
How do you calculate the amount of energy for nuclear fusion?
Energy = change in mass x speed of light^2
