Blog: Nuclear power - Advantages and Disadvantages

Dr Elisabetta Canetta, BSc Physics (Applied) Lecturer at St Mary’s University, Twickenham explores the advantages and disadvantages of nuclear power. Nuclear power. What do these two words stir in your mind? What is the first thing that crosses your mind when you hear them? I believe that what most people think of is danger, radioactive disaster, explosion of nuclear reactors (Chernobyl in 1986 is probably the most notorious), and so on. As with a background in nuclear physics I can assure you that nuclear power is not as bad as it can seem at first sight. As the old saying goes, “If you do not know, you cannot say”; so, let us explore further what nuclear power is about and its advantages and disadvantages. Nuclear power: What is it? It is an exothermic (i.e. it releases heat) nuclear (i.e. it involves an atomic nucleus) phenomenon through which heat is produced and then transformed into the electricity that makes our lives comfortable and cosy. Now the next question is: How is nuclear power produced? Nuclear power is generated in nuclear power plants. These are thermal power (i.e. they produce heat) stations in which the heat source is a nuclear reactor. “Nuclear reactor”. These two words could make some people feel threatened and unsafe. However, there is nothing to be afraid of. In fact, a nuclear reactor is a device that allows nuclear physicists, engineers, and technicians, to initiate, control and maintain a nuclear chain reaction, such as nuclear fission, which is the most commonly used nuclear reaction for the production of nuclear power. Nuclear fission happens when the nucleus of an atom, also called atomic nucleus (remember that an atom, which is the building block that makes up all matter including our own bodies, can be represented as a tiny solar system with the nucleus acting as the Sun and the electrons acting as the planets orbiting around it) captures a neutron (a sub-atomic particle with no electricity that, with protons, makes up an atomic nucleus) and because of the subsequent increase in its energy it splits into lighter nuclei (called “daughter” nuclei which are different from the “parent” nucleus that originated them). So far, so good; but how is heat produced (remember that this type of reaction is “exothermic”, i.e. it produces heat)? The laws of nuclear physics tell us that if we sum up the masses of all of the daughter nuclei formed in the process, we get a lower value than the mass of the initial parent nucleus. Hence, there is a loss in mass. However, for the fundamental law of physics: “energy cannot be created or destroyed but only transformed”; so if the “missing” mass (which for the world-famous Einstein’s equation E = mc², where m is the mass, E the energy, and c the speed of light, corresponds to energy) has not be destroyed, where has it gone? It has been transformed into “heat” which is then used to warm up our houses and to give us the electricity that we need to live our lives as we know them, with all their comforts and amenities. This type of reaction is called a “chain reaction” because during fission more neutrons are produced that can then be captured by other atomic nuclei and start a new fission reaction, and so on. This reaction continues and hence a steady production of heat and electricity is maintained. As we can see, the basic idea of a nuclear power plant is quite simple and straightforward. However, it goes without saying that caution needs to be taken in dealing with radioactive material, such as ²³⁵Uranium (the most used fuel for fission), and safety procedures must be in place at all times to make nuclear power as safe a source of energy as it can possibly be. Nuclear power has many “advantages”. Let us look at the most prominent: 1. It is a sustainable energy source (i.e. it can meet the increasing global demand for energy); 2. The amount of electricity produced by a nuclear power plant is very large and can easily meet the demand of industries and cities (e.g. currently there are 16 operative nuclear power plants in the UK and they generate 10,038 MWe – MegaWatt electric = 100000Watt electric. These 16 units generate about 18% of the UK electricity and all but one of these nuclear power plants will be dismissed by 2023); 3. It reduces carbon emission (i.e. the amount of greenhouse gases, such as carbon dioxide, emitted in the atmosphere in power generation is very low) 4. It is a very well-known method for the production of electricity and the costs to maintain a nuclear power plant are not excessive; 5. There are procedures in place for the recycling and reprocessing of the nuclear waste produced by nuclear power plants. The most common “recycling” process is the conversion of fertile ²³⁸Uranium into fissile plutonium: the uranium “captures” a neutron and with this newly acquired energy can undergo radioactive decay and transform into plutonium which is fissile, i.e. plutonium can undergo a nuclear chain reaction, which is the process that produces nuclear power. The “reprocessing” of used nuclear fuel allows to recover uranium (called “reprocessed uranium”) and plutonium and, therefore, to avoid wastage of valuable resources. This has a notable impact on our economy. However, nuclear power has also many “disadvantages”, some of the most important being: 1. The costs to build a nuclear power plant are very high because of the complexity of the radiation containment structures (i.e. structures that can prevent the leakage of dangerous radioactive substances in case of a failure in the nuclear reactors, as it happened in 2011 at Fukushima Daiichi); 2. Nuclear power plants are centralised power sources that require large infrastructure and coordination compared to decentralised power sources, such as wind and solar powers; 3. The most common nuclear fuel is uranium, which is found mainly underground and needs to be mined, which can cause health problems to miners and environmental contamination due to the high level of radioactivity of uranium; 4. The consequences of a nuclear disaster can be deleterious to the health and well-being of the three kingdoms of nature (animal, vegitation, and minerals) as the disaster at Chernobyl in 1986 has shown us all too well; 5. Disposal of radioactive waste is one of the major issues. However, great debate is there if radioactive waste is more manageable and less harmful than other toxic industrial waste. This is a topic in itself and this is not the right place to discuss such a complex issue. As you can see, nuclear power has many advantages and disadvantages and for this reason our society is divided into nuclear supporters and nuclear detractors. Personally, I believe that nuclear power could be the answer to our desperate need for a clean and sustainable energy. It is obvious that care needs to be taken when dealing with nuclear power but is this not true for many other energy sources (just think to coal and the environmental pollution that has caused in the past, e.g. the famous “London smog” in the 19^th and 20^th centuries, and all the precautions that are now in place when using coal as an energy source)? I leave it to the reader to decide if nuclear power as more advantages than disadvantages or vice versa.