Physics - 2.3 - Nuclear reactions - nuclear energy

What are the two main types of nuclear reaction?

Fission and fusion reactions.

What is nuclear fission?

The splitting of a large nucleus into two or more smaller nuclei.

What do fission reactions usually release, aside from energy?

Neutrons.

What is spontaneous fission?

The random splitting of a large nucleus into two or more smaller nuclei due to internal processes within the nucleus.

What is induced fission?

The (deliberate) splitting of a large nucleus into two or more smaller nuclei due to a neutron colliding with the nucleus.

What is important to remember about the atomic number and mass number on both sides of a reaction?

The atomic number and mass number will be conserved, so both sides will be equal.

What happens to the products of fission reactions?

They gain kinetic energy.

What is induced fission the basis for?

Nuclear power and nuclear bombs.

The splitting of a singular nucleus only provides a small amount of energy, how does the process release more?

The extra neutrons released during the fission of one nucleus can go on to cause fission in surrounding nuclei. This causes a chain reaction, in nuclear bombs this is uncontrolled and in nuclear power stations it is controlled by

How is the chain reaction controlled - nuclear bomb and nuclear power stations?

In nuclear bombs this is uncontrolled and in nuclear power stations it is controlled by absorbing some neutrons before they can split other nuclei, in order to provide a steady flow of energy.

What is fusion?

Two nuclei are joined together to make a larger nucleus.

What does nuclear fusion power?

The sun and the stars.

What else is fusion used for?

Hydrogen bombs, which are more powerful that nuclear bombs.

Which are more difficult to start, fission or fusion reactions?

Fusion reactions are more difficult to start.

Why are fusion reactions more difficult to start?

They require extremely high temperatures to overcome the repulsion of the two positive nuclei.

Which is harder to control, fission or fusion?

Fusion is harder to control than fission.

What are the advantages of fusion?

There is a plentiful supply of fuel and the waste products are less dangerous than fission.

What releases more energy, fission or fusion?

A singular fission reaction will release more energy than a single fission reaction, but the energy yield per kilogram of fuel is greater for fusion reactions.

Why is the energy yield per kg of fuel greater for fusion?

The nuclei used in fusion reactions are much smaller and so there are more nuclei per kilogram of fuel.

What is plasma?

A extremely hot state of matter consisting of free electrons and positive ions, as the electrons are stripped from the atoms.

Why is plasma needed for fusion reactions?

The temperatures are high enough for the nuclei to have enough kinetic energy to fuse on collision, nuclei are free to interact directly, the charged particles can move freely which increases the chance of collision.

How are the charged particles within a fusion reactor contained?

By a magnetic field.

Aside from plasma and a very strong magnetic field, what else would a fusion reactor need to be operational?

The walls of the reactor would have to be able to withstand high temperatures and would have to be cooled so they did not melt due to the fast-moving neutrons that are released.

What does the term mass-energy equivalence mean?

That mass and energy are essentially the same thing.

equation (mass-energy equivalence) E = …

E = mc²

The mass of products in fission and fusion reactions is different from the mass of …

reactants.

How can the energy released from fission and fusion reactions be determined?

It is the mass lost converted into energy.