Nuclear Fission And Fusion Flashcards
What is nuclear fission?
A chemical reaction that is used to release energy by splitting large and unstable nuclei into smaller ones
Describe in three steps what happens during nuclear fission
1- a neutron is absorbed by the unstable nucleus
2- the nucleus splits into 2 smaller nuclei that are roughly equal in size
3- gamma waves are emitted, aswell as 2 or 3 neutrons
Where is energy transferred to in all fission products?
Into the kinetic store
Describe what causes more fission reactions.
The released neutrons may be absorbed by other unstable nuclei
Describe what a chain reaction is in two points
- when neutrons released in a fission reaction go on to cause further fission reactions
- each released neutron if travelling at the right speed can be absorbed by another nucleus
How long can a chain reaction carry on?
For as long as any unstable nuclei remain
What are two uses of fission?
- generating electricity
- nuclear weapons
What nuclear fission element is used in nuclear power stations to generate electricity?
Uranium 235
What is the difference between controlled fission and uncontrolled fission?
Controlled fission is used to manage energy production while uncontrolled fission leads to explosive reactions
What do nuclear weapons rely on?
The fission of unstable nuclei
What causes an explosive?
When a chain reaction isn’t controlled
Describe nuclear FUSION in 4 steps.
- two lighter nuclei collide
- they join/ fuse together
- to form heavier nucleus
- energy is released from radiation
True or false the heavier nuclear that is produced from nuclear fusion is HEAVIER than the mass of the starting two combined nuclei.
FALSE- the heavier nucleus produced has less mass than the combined mass of the two starting nucleus
Which process releases more energy between nuclear fusion and nuclear fission?
Nuclear fusion
Why is fusion preferred over fission as an anregt source on earth? Give two reasons.
- large supply of hydrogen available for fusion (in sea water)
- the waste products, mainly helium, are NOT radioactive
Compare the process of nuclear fusion with fission
- nuclear fusion= light nuclei are JOINED to make a heavier one
- nuclear fission= heavy/ unstable nuclei SPLIT into lighter ones
What are 2 disadvantages of nuclear fission compared to nuclear fusion?
- Waste profits are radioactive
- releases less energy than fusion
State the two conditions for nuclear fusion to occur
- extremely high temperature
- high pressure
Explain why these conditions are needed for fusion to occur
- nuclei are positively charged, high temp needed to overcome the electrostatic repulsion between the nuclei
Describe what happens during nuclear fusion in three steps
- small nuclei fuse together
- to produce a larger nucleus
- releasing energy
What is the role of control rods in nuclear fission?
absorbs excess neutrons to control the rate of fission
What is the moderator in nuclear fission made from?
Water
What is the similarity of nuclear fusion and nuclear fission?
Both processed release energy
What is the role of the moderator and what is it made from?
- water or graphite
- to slow neutrons down to increase chance of absorption
What is the role of the shielding in nuclear fission?
To absorb harmful radiation released by radioactive products of fission
