How does a nuclear power plant work?
From the chain reaction to electricity in your home.
A fission nuclear power plant works much like a thermal power plant — with one fundamental difference: instead of burning coal or gas, it uses the heat from nuclear fission.
The process in 4 steps
- Fuel: enriched uranium rods sit inside the reactor.
- Reaction: neutrons bombard the uranium, triggering the chain fission reaction.
- Heat: the released energy heats the water in the cooling system.
- Electricity: the steam drives turbines that generate electrical power.
The reactor core is kept submerged in water — which acts as a moderator (slowing down neutrons) and a coolant (removing heat).
In Brazil — Angra 1 and Angra 2
Brazil operates two nuclear power plants in Angra dos Reis (RJ):
- Angra 1: in operation since 1985, output of 657 MW. In November 2024, CNEN authorised operation until 2055.
- Angra 2: in operation since 2001, output of 1,350 MW.
Together they account for around 3% of national electricity generation. Angra 1 generated 4.78 million MWh in 2023 — enough energy to supply a city of 2 million people.
Source: NucNet, November 2024.
Angra 3
It will be a twin of Angra 2 with 1,405 MW. Currently under construction. Eletronuclear projects the start of operations in 2031.
Source: World Nuclear Association, "Nuclear Power in Brazil", Nov. 2025.