nuclear fission & fusion

What is nuclear fission

The slitting of a large unstable nucleus to release energy and smaller products with kinetic energy

What is fusion

Where 2 small nuclei are combined to give a large nuclei

Requires very high pressures and temperatures and collision rate

Describe process of nuclear fusion

In nuclear fusion two light nuclei collide at high speed and join to create a larger heavier nucleus

Why does heavier nucleus created in fusion have less mass then the two separate light nuclei had

Heavier nucleus’s doesn’t have as much mass as two separate light nuclei did some of the mass of the lighter nuclei is converted to energy and released

What is spontaneous fission?

Spontaneous fission is when the fission is unforced, and the atom splits by itself.

This is very rare.

Where is nuclear fission carried out on earth?

In nuclear power stations.

What are the steps in a nuclear fission chain reaction?

1. A neutron is fired at an unstable nucleus (e.g. uranium-235), causing it to split apart.

2. The unstable nucleus splits into 2 daughter nuclei and 2 or 3 neutrons. It also emits a large amount of energy as gamma radiation.

3. The 2 or 3 neutrons that were released are then absorbed by other unstable nuclei and this repeats the process from the previous step.

4. This process then occurs over and over again in what we call a chain reaction.

Why are boron used in nuclear fission (/chain reactions )

They absorb neutrons which slows down the chain reaction and controls the amount of energy released

How do boron control rodsreduce the risk of nuclear meltdown?

Boron control rods can be lowered into the nuclear reactor to absorb neutrons and slow the chain reaction.

This prevents it from getting out of control and leading to a meltdown.