Nuclear Fission

Two types of Nuclear Power

Nuclear fission

Nuclear fusion

What is nuclear fission?

The splitting of nuclei of large atoms

Large atoms examples:

The isotopes of uranium-235 or plutonium-239

What is fissile fuel?

An isotope that can easily undergo nuclear fission when struck by a neutron, releasing energy.

Give me an example of a fissile fuel

Uranium-235

Plutonium-239

1)

A big atom (like U-235) absorbs a neutron

2)

This makes the atom unstable, causing it to split into 2 smaller atoms

3)

When the atom splits, it releases energy in the form of heat

4)

The split also releases more neutrons, which can hit other large atoms, causing them to split and lead to a chain reaction

Why has nuclear power not expanded?

- Very expensive

- Strong public opposition due to concerns over safety following Chernobyl (1986, Ukraine) and Fukushima (2011, Japan)

- Uncertainty over the permanent disposal of radioactive waste

- Uncertainty over the total costs of nuclear power since no commercial reactor has been fully decommissioned

Energy Density

A small amount of fuel is needed to release a large amount of energy.

1kg of uranium fuel (0.7% U-235) can release as much energy as....

13,000kg of coal

Embodied Energy

Uranium needs to be purified & concentrated & chemically processed to produce fuel, whereas coal does not

Finite Resource

Fissile materials like uranium and thorium are non-renewable resources, so quantity declines as they are used.

However, a huge amount of uranium exists, but most is found in low purity deposits and they cannot be exploited economically

Environmental Impacts

- Mining and processing uranium (and mining thorium ore to make nuclear fuel) leads to habitat loss, noise, dust, turbid drainage water, hazardous wastes

- The high embodied energy of materials used contributes to global climate change

Economic Issues

Only a few old reactors have been fully decommissioned, and costs were much higher than anticipated

Nuclear fission VS Coal

A reactor only needs around 18,000-80,00kg of fuel replaced each year

Whereas 9,000,000kg of coal would be needed to burnt everyday to have a similar energy output