Nuclear Fission and fusion Flashcards
What is nuclear fission
Nuclear fission is the splitting of a large and unstable nuclei into smaller nuclei
How much energy does fission release
LOTS of energy
What are the two ways fission can occur
-Fission either occurs spontaneously (unforced + by itself) this is rare however
-OR by absorbing a neutron making the nucleus even more unstable causing it to split - forced method.
Describe the process of Fission
-Start with large unstable nuclei
-That nuclei then absorbs a neutron making it more unstable
-The nuclei then splits into two daughter nuclei, more neutrons are produced and lots of energy is released
-This process then repeats in a chain reaction.
What happens when fission is not controlled properly?
If not controlled properly, the reaction can get out of hand and release significantly large amounts of energy e.g. nuclear bomb.
How is fission controlled in nuclear reactors?
Rate of fission is controlled by control rods
They are lowered into the reactor to absorb neutrons and slow down the rate of reaction.
Pros of fission
Uranium or plutonium fuel is relatively cheap
-Large and steady amounts of energy are produced
-Doesn’t produce greenhouse gases unlike fossil fuels
Cons of fission
-Nuclear power plants are expensive
-Waste is also expensive to dispose of as it has to be buried underground in bunkers
-Risk of major disaster, although very unlikely if controlled properly (Chernobyl)
-This makes people suspicious of using nuclear energy
Why are nuclear reactors surrounded by thick concrete
To slow down the rate of fission by absorbing neutrons and ionizing radiation
What is nuclear fusion?
Fusion is when 2 smaller nuclei fuse together to form a larger nuclei
What releases more energy, Fusion or fission
Fusion produces a lot more energy than Fission
Where does Fusion occur
Only occurs in stars
Equation to calculate energy
E = Mc2
Does nuclear fusion produce any radioactive waste?
No
What are the conditions needed for fusion
Extremely high temperature (10,000,000C)
and very high pressure.
Differences between fusion and fission
Fusion:
-Fusion of lighter nuclei into heavier nuclei
-Releases tons of energy (way more than fission)
-Only happens inside of stars due to the extremely high temperature and pressure required
Fission:
-Large unstable nuclei splitting into 2 smaller nuclei
-Produces lots of energy (not as much as fusion)
-Used on Earth to produce energy
What are the charges of Beta and Alpha particles
Beta is negatively charged and Alpha is positively charged
Give 2 differences between Alpha radiation and Beta radiation
-Alpha has a higher mass than Beta
-Beta particles are negatively charged whereas Alpha particles are positively charged
What are the hazards of being surrounded by Radon gas
-Radon easily enters the body through inhalation as it is a gas, which can cause irradiation in internal organs, it is also alpha which is extremely dangerous when inside the body.
Define the term half-life
The amount of time taken for a radioactive atom’s activity to halve.
Describe the process of fission in uranium-235
-Uranium absorbs a neutron and becomes uranium-236
-The nuclei then splits producing more neutrons and two daughter nuclei
-Releases lots of energy
-The reaction then repeats
Why do coolants in the reactor have a pressure exerted on them?
-The gas particles collide with the tube walls
-Exerting force on the walls
-Pressure is force exerted over an area
What is meant by a chain reaction
Fission releases neutrons
-Daughter cells from previous reaction then absorb the neutrons undergoing fission
Why do nuclei move apart from each other
As they are both positively charged, they repel from each other
Why does fusion only occur at high temperature and high pressure
-The nuclei are similarly charged so they repel
-They move too slowly at low temperature, so they can’t get close enough for fusion to occur
Describe the role of shielding around a nuclear reactor
-It prevents radiation escaping the nuclear reactor by absorbing neutrons.
Why is a fusion reactor possibly safer than a fission reactor
-The products aren’t radioactive
-So there is no risk of mutation of cells and cancer
-The products don’t need to be stored long-term as they aren’t as much of a health risk.
-The reactants aren’t as hazardous.
Name a fuel used in the reactor of a nuclear power station
Uranium or plutonium
If i nucleus is in a fusion reactor and experiences a force to the left, how must the nucleus be behaving?
-The nucleus must be moving downwards.
What happens to an atoms proton number and number of neutrons when beta decay occurs?
-It gains 1 proton and loses one neutron.
