4th - Fission And Fusion Flashcards
Products of nuclear fission
- 2 daughter nuclei (smaller, not always identical to each other)
- small no. Of neutrons
- release energy
(Combined atomic mass of daughters and neutrons = parent atomic mass).
Where are fission reactions used
Nuclear power stations
Submarines
Process of nuclear fission
- Neutron collides with parent nucleus = unstable
- nucleus splits
- energy released as kinetic energy
What is radioactive decay
When an
- unstable nucleus loses energy
- by emitting ionising particles and radiation
What is nuclear fusion
- two small nuclei fuse to form a larger nucleus
- release energy inside stars (energy source)
- unable to generate enough energy on earth
How does a chain reaction occur?
- Neutrons released in fission reaction can be absorbed by other nuclei
- nuclei split and release more neutrons
- these neutrons can be absorbed by other nuclei - and so on
What does the graphite core act as
A moderator
What does the graphite core moderator do
- neutrons are slowed down
- increasing the rate of fission
What do control rods do
- absorb neutrons
- increases or decreases the rate of fission
What are reactor vessels made of
Steel
What is shielding made of
Concrete
What does shielding do
- Thick Layer of concrete
- prevents any radiation or neutrons escaping
Differences between nuclear fusion and fission
Fusion
- energy source for stars
-can’t happen at low temps or pressures.
- very difficult to make a fusion power station
Fission
- energy source for nuclear power stations
- can happen at low temps or pressures
What do positive charges do
Repel each other - electrostatic repulsion
What benefit does the speed of the particles have for attraction
The faster the particles are, the closer they will get to each other before repelling
