Nuclear energy
Nuclear energy still raises a lot of controversy in Poland. In this case, scientific facts are mixed with false stereotypes, and ecology with politics. It is known that radioactive materials are dangerous and the risk of failure exists. But how does a modern nuclear power plant work in practice? And how does nuclear energy produce electricity? Let's take a look at this.
Nuclear energy – principle of reactor operation
Schematically, a nuclear power plant can be divided into two parts. In the first one, nuclear reactions take place, generating large amounts of heat. The second one is more conventional, converting heat into electricity. In principle, it differs little from similar parts of coal-fired power plants. To put it simply, it is about generating alternating current using a set of turbines that are set in motion by hot steam. Therefore it is a thermal power plant.
This heat is generated by controlled nuclear reactions in the reactor. The fuel are fissile materials, i.e. chemical compounds containing uranium-235 or plutonium-239. These elements are capable of chain reactions. Therefore, as a result of the splitting of one atom by a neutron, other neutrons are released, which are able to split nearby atoms, which quickly causes the splitting of the next ones, and so on. In nuclear weapons, this occurs in an avalanche and uncontrolled manner, causing an explosion. In nuclear energy, most of the kinetic energy of atoms and radiation are slowly converted into the thermal energy of water. Reactors allow the conditions of a chain reaction to be carefully regulated so that it cannot get out of control or stall.
This is the general principle of operation, although, of course, there are plenty of technical solutions to control, safety and increase the efficiency of nuclear reactions. They make nuclear energy safe and – compared to conventional power plants – ecological. No fossil fuels are burned, no greenhouse gases, dust, ash or slag are generated. Nuclear power plants do not smoke. Their chimneys are used to cool water, and pure water vapor comes out of them. Unfortunately, large nuclear reactors are very advanced devices. Their construction requires a lot of work and money to meet the strict safety requirements. A sure solution to this are SMR reactors, which have become more and more popular recently.
SMR power plant – a way for the nuclear energy of the future?
The abbreviation stands for Small Modular Reactor. Its operating principle is identical to that of a "traditional" reactor. This solution has nothing to do with the type of nuclear fuel, reaction control system, cooling or electricity generation. The difference is in the design. Modularity means that such a reactor is not constructed on the construction site of the power plant. Instead, it is manufactured in a separate factory as one unit and shipped to the site. The first assumption requires the second: small size, otherwise transport would be unprofitable. Therefore, the expected electrical power of SMRs will be lower than in older nuclear power plants: from 20 MWe to 300 MWe (MWe - megawatt of electrical power).
Interestingly, SMR is not a new invention at all. Nuclear-powered submarines and aircraft carriers have had to use small, ready-to-install solutions for many years. SMR designs draw heavily on them. The aim is to reduce costs and simplify procedures while maintaining complete safety. This is a practical approach to the gradual process of moving away from coal-fired energy. The reality is ruthless: coal, oil and natural gas resources will be exhausted within the next few generations. Uranium resources on Earth may last for thousands of years. The use of alternatives to fossil fuels has already begun to help humanity meet its growing energy appetite.
That is why today there are already several dozen SMR projects. Most are at the concept or construction stage. The breakthrough occurred in December 2022 in the Chinese city of Weihai, when two HTR-PM reactors reached full power - a total of 210 MWe. Many energy companies (including Polish KGHM and Orlen) are currently planning to launch their own Small Modular Reactor. In the coming years, this technology will be completely mature, tested and gradually becoming cheaper. already begun to help humanity meet its growing energy appetite.
Safety of nuclear power plants
How safe are nuclear power plants?
Nuclear power plants use large amounts of particularly dangerous materials in which powerful reactions occur. Therefore, safety standards are very strict. In Poland, the National Atomic Energy Agency conducts nuclear supervision. This is a group of inspectors that supervises all entities working with ionizing radiation sources. The construction of a new nuclear power plant requires the preparation of a lot of important documentation - even several thousand pages! All this to prove the safety of the future installation. SMR has a certain advantage here - as a smaller and simpler structure, it requires slightly simplified procedures.
What does it look like in practice to ensure control over dangerous nuclear fission? This reaction takes place in fuel rods that contain uranium or plutonium. Between them there are control rods made of special materials that have the ability to absorb neutrons. As we know, it is neutrons that spread like avalanches that cause atoms to split. The simple (in principle) operation of inserting a rod with a absorber between the uranium rods slows down the reaction or stops it. In addition, there are safety systems that involve quickly flooding the reactor with cold water. This causes rapid cooling when nuclear reactions would produce too much heat.
Control systems require normal power supply, which may also fail due to random reasons. In such a case, power plants have their own diesel generators to provide backup power. There are even passive systems that require no human intervention or electricity. They operate automatically, e.g. thanks to automatic shutdown and gravitational flooding of the reactor with water. All this makes nuclear energy a safe source of efficient and clean energy.