Atomic Energy

First of all, we should know the very basic atomic energy generating process. This information can de found in portuguese at: http://www.df-net.com.br/nuclear/onuclear.htm .

When you break the structure of any atom, as a result, it releases energy. It's very difficult to break the structure of a small atom like hydrogen. However, we can find in the nature some big atoms like uranium and plutonium, for example. The uranium atom is so big that you don't need to make any effort to break its structure. It happens spontaneously, liberating lots of heat. That's what we call nuclear fission. A nuclear power plant converts this heat in electricity.

Below you can see how a nuclear power plant works. That's the model of a Brazilian plant called Angra I. It's powered by a PWR reactor using enriched uranium and water under pressure.

I

This image belongs to http://www.cnen.gov.br/cnen_99/educar/en_3.htm  .

The pressure vase contains water. This water refrigerates the nuclear reactor, circulating in a closed circuit called primary circuit. Uranium is a metal that melts very easily. If we don't refrigerate it, we are having a nuclear melt-down. The other circuit is called secondary circuit and is heated by the primary one. The whole thing is called steam generator. The steam inside the second circuit is going to move the turbine to generate electricity. Please note that the primary and secondary circuits' water don't make any contact. These circuits are also called heat exchangers.

The reaction inside the reactor is called chain reaction. When the moderator or the control bars absorb the neutrons, the uranium atoms start colliding and splitting up releasing a huge amount of heat and gamma rays energy. The uranium is also called fuel element. If you watch the last 007 film, you'll see an atomic submarine with a plutonium reactor and this structure that is described above.

After knowing the basic process, we should know learn a bit about the plant itself. This information were find in Portuguese  on the following site:

http://www.eletronuclear.gov.br . This page is made by Angra II and Angra III building team. The sizes are all refering to these power plants.

THE REACTOR BUILDING

That's the main building is where the reactor and the main parts of the steam generator are. The building is cylindrical shaped, 58m tall and the diameter is 40m. The width of its concrete structure is 75cm. Inside  there is a stainless steel pot which contains some parts of the steam generator like the pressure vase and the reactor nucleus.

THE SECURITY BUILDING

Inside this building there are the security system and controls.

THE FUEL BUILDING

Here the new and used fuel is kept. There are all the managing tools as well.

THE TURBO-GENERATOR BUILDING

In this building the heat energy is converted in electricity. The turbine and the generator are inside as well. All the Brazilian Angra I's power is generated by a single turbo-generator.

THE AUXILIARES BUILDINGS

We can find in this building the auxiliares components of the steam generator. The general control room is also localized here, as well as the  air conditioning system.

Going deep into nuclear reactors, we can see several different kinds of reactors. A general view of some kinds is porvided below.

BWR - Boiling Water Reactor

This reactor uses water as a moderator and enriched uranium as fuel element.

The steam formed goes direct to the turbine, without any intermediate heat exchanger.

PWR - Pressurized Water Reactor

This reactor uses enriched uranium as fuel element and water under pressure as coolant.

LWR - Light Water Reactor

General name for PWR and BWR reactors.

EPR - European Pressurized Reactor

Hi-tech European reactor that uses pressurized water as coolant. It was created by french and germans to be used on the next two decades.

FBR - Fast Breeder Reactor

This reactor produces more fissile material than it consumes. The chain reaction is started with fast neutrons.

HWR - Heavy Water Reactor

This reactor uses natural uranium as fuel element and heavy water as moderator. This water can be pressurized also (PHWR). It was created in Canada and it's good because does not need enriched uranium. However, only countries with big resources of water can easily have heavy water. Another name for this reactor is CANDU (Canada, Deuterium, Uranium).

RBMK - Reaktor Bolshoy Moschnosty Kipyaschiy (High Power Boiling Water Reactor)

This russian reactor uses graphite and light water moderator. Chernobyl was powered by this reactor.

VVER - Voda-Vodyanoi Energiticheskiy Reaktor (PWR)

That's the Russian version of PWR

The first UKAEA United Kingdom's first reactor. It used graphite as moderator and carbon dioxide as coolant.

Sources in Portuguese

HTTP://WWW.DF-NET.COM.BR/NUCLEAR/ONUCLEAR.HTM 

HTTP://WWW.ELETRONUCLEAR.GOV.BR 

HTTP://WWW.CNEN.COM.BR 

- Uranium 235 => The atomic mass is 235 and it's also called fissile uranium. That's the only uranium isotopic that can be 'split'. Out of 100 collisions of a slow neutron with U235, 15 atoms of U236 are formed and 85 are 'split' reliesing energy. The radioactive period is 7,2 X 10^9 years. U235 is 0,71% of natural uranium.

Heavy water is composed by two deuterium atoms and one oxygen atom. Deuterium is an hydrogen isotopic with a proton and a neutron, instead of a single proton. It's a very good neutron moderator.