IT
USA
DE
FR
ES
USA
IT
EN
DE
ZH
ES
FR
PT
JP
RU
AR
KR
PL
RO
VN
HE
TR
CS
HR
DA
FI
EL
NL
SR
SK
SV
HU
Technological development over the years allowed to acquire knowledge of extraordinary physical principles such as: x-ray discovery which revolutionised medicine, Newton’s work which allowed Einstein to work on the theory of relativity or the atom discovery which led to nuclear fission.
All these accomplishments have always divided the opinion of the scientific community, who considered these discoveries magnificent but at the same time dangerous in certain ways.
For many years now, the society of the 21st century have been questioning a discovery that revolutionised the world: we’re talking about the nuclear power!
Nuclear, or atomic, energy is the energy obtained from nuclear reactions and radioactive decay in the form of kinetic energy and is used by numerous technologies, such as nuclear power plants to obtain electricity. In 2020, nuclear power produced only 10% of global electricity, even though it is one of the safest sources in terms of deaths per unit of energy produced. So, why does the public have reservations about using this technology?
Let’s find out together how does a nuclear power plant works and let’s see each step in detail.
Nuclear power plants are huge and very complex buildings which are used as power plants and produce energy through nuclear fission.
Nuclear fission is a reaction in which the nucleus of a heavy element decays by emitting a large amount of energy; the reaction occurs when a heavy metal nucleus, such as uranium-235, is bombarded, i.e. hit, by a neutron that breaks up the nucleus, releasing three new neutrons and energy.
One of these neutrons is absorbed by another uranium-238 nucleus and is lost in the balance, a second neutron can escape from the system, and the third neutron hits another uranium-235 nucleus, which breaks up, releasing more neutrons, which in turn will hit other uranium-235 nuclei, thus creating a chain reaction.
This reaction is the core of the nuclear reactor, which handles the decay of heavy material in a controlled manner.
Now let’s see what a nuclear power plant looks like and how it works!
The facility is divided into two islands: the first one corresponds to the building that contains the reactor and is called nuclear island, while the second one is called conventional island where the nuclear power obtained is handled and transformed into electricity.
All these accomplishments have always divided the opinion of the scientific community, who considered these discoveries magnificent but at the same time dangerous in certain ways.
For many years now, the society of the 21st century have been questioning a discovery that revolutionised the world: we’re talking about the nuclear power!
Nuclear, or atomic, energy is the energy obtained from nuclear reactions and radioactive decay in the form of kinetic energy and is used by numerous technologies, such as nuclear power plants to obtain electricity. In 2020, nuclear power produced only 10% of global electricity, even though it is one of the safest sources in terms of deaths per unit of energy produced. So, why does the public have reservations about using this technology?
Let’s find out together how does a nuclear power plant works and let’s see each step in detail.
Nuclear power plants are huge and very complex buildings which are used as power plants and produce energy through nuclear fission.
Nuclear fission is a reaction in which the nucleus of a heavy element decays by emitting a large amount of energy; the reaction occurs when a heavy metal nucleus, such as uranium-235, is bombarded, i.e. hit, by a neutron that breaks up the nucleus, releasing three new neutrons and energy.
One of these neutrons is absorbed by another uranium-238 nucleus and is lost in the balance, a second neutron can escape from the system, and the third neutron hits another uranium-235 nucleus, which breaks up, releasing more neutrons, which in turn will hit other uranium-235 nuclei, thus creating a chain reaction.
This reaction is the core of the nuclear reactor, which handles the decay of heavy material in a controlled manner.
Now let’s see what a nuclear power plant looks like and how it works!
The facility is divided into two islands: the first one corresponds to the building that contains the reactor and is called nuclear island, while the second one is called conventional island where the nuclear power obtained is handled and transformed into electricity.
Externally, the nuclear island presents itself as a huge block of concrete to isolate the reactor placed at the centre of the facility. In the reactor we find the core or nucleus composed of fissile material, usually a mixture of uranium-238 and uranium-235. A moderator, usually heavy water or graphite, is used to slow down the generated neutrons, increasing the probability of fission.
There are also metal control rods in the reactor that are used to capture excess neutrons, and are inserted into the core to moderate the power of the reaction, and if necessary to stop the process in case of criticality. Should the reaction reach the critical level, it would release an enormous amount of energy that would cause the core to melt, destroying the containing walls and dispersing radioactive material into the environment. The fragments of the reaction slowing down produce heat that is captured by a heat-transfer liquid surrounding the uranium core. To put it simply, the heat-transfer liquid acts in the same way as hot water in a heating system with radiators, in which the water carries the heat generated by the boiler to various points in the room. The compressed heat-transfer liquid reaching the core has a temperature of 290 °C, and increases to 320 °C at a pressure of 15 MPa so that it does not boil.
The heated liquid passes through a steam generator, in which a saturated wet vapour is produced, at this point it passes through a moisture separator that transforms it into a saturated dry vapour, and with a conductor system it is transported to a steam turbine located in the conventional island at a final temperature of 290 °C at a pressure of 5 MPa. A pressuriser is used to keep the pressure stable. The turbine is a driving machine that uses the thermal energy of steam, converting it into mechanical work. Using the converted energy, the turbine moves an alternator, which is used to produce electricity; the same principle is used in the most common fuel-fired power stations, as well as in hydroelectric power stations or wind farms. As we have seen, the whole process generates large quantities of steam, which must be managed once it leaves the turbine; by cooling it, the steam returns to a liquid state and can be reused again in the process. A condenser is placed below the turbine in order to cool the steam and thanks to a coolant, it is converted into water. The mass of water coming out of the condenser has a very high temperature, and cannot be released into the basin of origin, otherwise it would damage the ecosystem. This is why it is preferred to build nuclear power plants near a river, a lake or by the sea, where the large masses of water can lower the temperature of the condenser water gradually without causing damage. For power plants that are built inland, there is a need for a closed cooling circle; the most commonly used system are cooling towers with natural circulation or forced circulation, with the help of huge fans.
There are also metal control rods in the reactor that are used to capture excess neutrons, and are inserted into the core to moderate the power of the reaction, and if necessary to stop the process in case of criticality. Should the reaction reach the critical level, it would release an enormous amount of energy that would cause the core to melt, destroying the containing walls and dispersing radioactive material into the environment. The fragments of the reaction slowing down produce heat that is captured by a heat-transfer liquid surrounding the uranium core. To put it simply, the heat-transfer liquid acts in the same way as hot water in a heating system with radiators, in which the water carries the heat generated by the boiler to various points in the room. The compressed heat-transfer liquid reaching the core has a temperature of 290 °C, and increases to 320 °C at a pressure of 15 MPa so that it does not boil.
The heated liquid passes through a steam generator, in which a saturated wet vapour is produced, at this point it passes through a moisture separator that transforms it into a saturated dry vapour, and with a conductor system it is transported to a steam turbine located in the conventional island at a final temperature of 290 °C at a pressure of 5 MPa. A pressuriser is used to keep the pressure stable. The turbine is a driving machine that uses the thermal energy of steam, converting it into mechanical work. Using the converted energy, the turbine moves an alternator, which is used to produce electricity; the same principle is used in the most common fuel-fired power stations, as well as in hydroelectric power stations or wind farms. As we have seen, the whole process generates large quantities of steam, which must be managed once it leaves the turbine; by cooling it, the steam returns to a liquid state and can be reused again in the process. A condenser is placed below the turbine in order to cool the steam and thanks to a coolant, it is converted into water. The mass of water coming out of the condenser has a very high temperature, and cannot be released into the basin of origin, otherwise it would damage the ecosystem. This is why it is preferred to build nuclear power plants near a river, a lake or by the sea, where the large masses of water can lower the temperature of the condenser water gradually without causing damage. For power plants that are built inland, there is a need for a closed cooling circle; the most commonly used system are cooling towers with natural circulation or forced circulation, with the help of huge fans.