3 Nuclear Energy

 Nuclear Energy 

The common definition for nuclear energy is the energy released by a chain reaction, especially by fission (division or splitting into two or more parts) or fusion ( occurs when two atoms slam together to form a heavier atom ).

Practically speaking, nuclear energy uses fuel made from mined and processed uranium to make steam and generate electricity.

Nuclear generation is the only source of electricity that can produce a constant supply of power – known as baseload power—reliably without emitting greenhouse gases.

Nuclear energy has one of the lowest environmental impacts on land and natural resources of any electricity source.

How does it work?

A nuclear reactor produces electricity in much the same way other power plants do. 

The chain reaction produces the energy, which turns water into steam. 

The pressure of the steam turns a generator, which produces electricity.

The difference is in how the heat is created. 

Power plants that run on fossil fuels burn coal, oil or natural gas to generate heat. 

In a nuclear energy plant, heat is produced from splitting atoms – a process called nuclear fission.

Nuclear reactor creates heat that is used to make steam.

The steam turns a turbine connected to an electromagnet, called a Generator 

(The generator produces electricity).

In a Pressurized Water Reactor (PWR) – the type of reactor which high pressure prevents water in the reactor vessel from boiling. 

The super-heated water is carried to a steam generator, which is made up of many small pipes. 

The heat in these pipes is used to turn a second, isolated, supply of water to steam, which is in turn used to drive the turbine. 

The water from the reactor is pumped back into the reactor vessel and reheated. 

The steam from the turbine is cooled in a condenser and the resulting water is sent back to the steam generator.

Uranium

Enriched uranium is the fuel for nuclear reactors. 

Uranium is an abundant, naturally radioactive element found in most rocks. 

As uranium breaks down or decays, it produces heat inside the Earth’s crust. 

A similar process generates heat inside a nuclear reactor.

Factors for Site Selection of NPPs

✓Availability of Water: working fluid

✓Distance from Populated Area: danger of radioactivity

✓Nearness to the load centre: reduction in transmission cost

✓Disposal of Waste: radioactive waste

✓Accessibility by Rail and Road: transport of heavy equipment

Advantages

✓Reduces demand for fossil fuels

✓Quantity of nuclear fuel is much less: thus reducing transport and resulting costs

✓Area of land required is less: compared to a conventional plant of similar capacity

✓Production of fissile material

✓Location independent of geographical factors: except water requirement

Disadvantages 

✓Not available for variable loads (load factor-0.8): as the reactors cannot be controlled to respond quickly

✓Economical reason should be substantial

✓Risk of leakage of radioactive material

✓Further investigation on life cycle assessment and reliability needs to be done

✓Perception problems