Is The Future of Nuclear Power Generation IV Reactors?

By Andrew Quaal

Image by Gerd Altmann from Pixabay

Why we need nuclear energy

The world is in the middle of a climate crisis. Temperatures are rising faster and faster, and this will lead to detrimental effects on the planet and all that call it home. According to the UN, the world must cut its carbon emissions in half by 2030 and to zero by 2050. Between coal, oil, and natural gas, energy is one of the main culprits contributing to climate change. Together, we need to move away from these energy sources and towards renewable ones that are carbon zero if we have any hope of reaching that goal. These energy types include solar, wind, hydro, and a less popular candidate as well: nuclear. Nuclear energy hasn’t always been the most widely accepted, but it is extremely safe and extremely effective. Currently, Generation IV nuclear reactors are being developed to progress nuclear technology and help fight the climate crisis, moving us towards the goals we must reach.

What are the four generations of nuclear power?

Since the first nuclear reactor was invented in 1942 by Enrico Fermi, reactor technology has progressed greatly over the years, becoming more advanced and well suited to face the problems modern society has to address. These innovations have been separated into generations, with the earliest demonstration reactors being Generation I and modern commercial reactors being Generation II and III. Now, looking to the future, Generation IV reactors are currently being developed and built to help push nuclear energy farther forward, making it safer, more effective, and more economically feasible. This movement is crucial as nuclear power is one of the main solutions to achieving carbon zero energy and fighting climate change. We need to eliminate our dependence on fossil fuels, and nuclear energy is one of the main avenues to reach that goal by 2050.

How do nuclear reactors work?

Nuclear reactors generate power the same way that most power sources do, by using steam or some other kind of fluid to rotate a turbine inside an electromagnetic field. The main difference between varying kinds of generators is how that steam is created. In a coal plant, coal is burned as a fuel, and the heat it generates creates steam by vaporizing water. In a nuclear reactor, the fuel is made up of radioactive material, typically some form of uranium or plutonium, and this is where the nuclear reactions take place. This reaction is called fission, and it consists of large atoms being split apart when neutrons collide with them. Splitting these atoms releases enormous amounts of energy and more neutrons, causing a nuclear chain reaction. The nuclear energy is then used to heat water into the steam that turns the turbine, like a coal plant. However, this nuclear reaction is completely carbon free, unlike burning coal which releases tons and tons of carbon emissions. Generation IV reactors take this process and adapt it in various ways to increase the reactor’s efficiency, safety, and economic benefits.

The Six Types of Generation IV Reactors

Molten Salt Reactor (MSR)

The main difference between a typical lightwater reactor (LWR), the most common reactor used today, and a molten salt reactor (MSR) is that the uranium fuel in the reactor is combined with a salt in a molten mixture. This mixture acts as both the coolant and the fuel, rather than having a water coolant that circulates throughout the reactor, regulating the temperature, like in an LWR. This allows the reactor to operate close to atmospheric pressure, removing the need for expensive containment systems and reducing the risk of any sort of accident from a pressure leak. Also, the MSR can operate at much higher temperatures than an LWR. These higher temperatures increase the thermal efficiency of the reactor, resulting in a higher power output. The MSR’s lower cost and higher efficiency makes it an excellent choice for countries looking to build new reactors, leading to the ultimate goal of carbon zero energy.

Very High Temperature Reactor (VHTR)

The Very High Temperature Reactor (VHTR) is a graphite moderated, gas cooled reactor that can operate at extremely high temperatures. In the VHTR, the fuel comes in the form of coated fuel particles, like TRISO Particles. The shape of the fuel depends on the specific reactor, ranging from blocks to spheres, but they are essentially a core of some nuclear fuel surrounded by several layers of graphite or other carbon-based materials. This structure allows the fuel to withstand the high temperatures of the reactor where other fuel types could not. Most commonly, helium is used as the coolant due to it being an inert gas, as it does not react with any materials nor become radioactive when in contact with other radioactive materials. Due to the VHTR’s high temperatures, it can also be used to help replace other fossil fuel reliant processes like desalination and hydrogen production, eliminating emissions created by energy production and other forms of industry.

Supercritical-Water-Cooled Reactor (SCWR)

The Supercritical-Water-Cooled Reactor (SCWR) is a modified version of the traditional LWR. The main difference is the SCWR operates above the critical point of water. Supercritical water behaves neither like a liquid or a gas, so there is no need to vaporize the fluid. Therefore, less energy is needed to heat the water because there is no phase change between liquid and gas. This increases the efficiency of the reactor to 44% as compared to an efficiency of 34–36% for current reactors. This increase in efficiency also reduces the waste heat given off by the reactor significantly. Additionally, by using supercritical water, the reactor has a high power density, allowing for a smaller core and smaller containment unit. All of these advantages result in the SCWR having overall lower costs, making it a much more economically feasible option.

Gas-Cooled Fast Reactor (GFR)

The Gas-Cooled Fast Reactor (GFR) is very similar to the VHTR, as both have a helium coolant and operate at high temperatures, so it also operates with a high efficiency like the VHTR. However, the GFR differs because it is a breeder reactor, meaning it can be used to produce new nuclear fuel as well as electricity. The GFR can also use several different types of fuel, including uranium and thorium. When thorium is used as a fuel, the reactor creates Uranium-233 as a byproduct, which can then be used as fuel in other reactors. Breeder reactors are very useful tools as they can be used to help produce fuel for other reactors and use up waste from other reactors. However, there are concerns over the fact that the byproducts produced can be used in nuclear proliferation, but as nuclear detection and reactor technology improves with reactors like this one, breeder reactors like the GFR are more and more plausible.

Sodium-Cooled Fast Reactor (SFR)

The Sodium-Cooled Fast Reactor (SFR) utilizes molten sodium metal as the coolant for the reactor, as it has a very high power density. Using sodium as a coolant has lots of advantages. For example, sodium is able to absorb lots of heat, which makes it difficult for the SFR to overheat. Due to its high boiling point, the SFR can operate near atmospheric pressure, reducing any risk of a steam explosion. Additionally, the SFR can utilize regular fuel as well as spent fuel from other reactors, so it can help to reduce the amount of nuclear waste produced by recycling it. Overall, the SFR has lots of built-in safety systems that will lower the cost and make this a widely applicable reactor.

Lead-Cooled Fast Reactor (LFR)

The Lead-Cooled Fast Reactor (LFR) is very similar to the SFR, but it utilizes a molten lead coolant rather than sodium. One benefit of the LFR is that lead also serves as a neutron reflector, keeping the neutrons contained within the fuel. By containing neutrons, the reactor prolongs the reactions happening in the fuel because there are more neutrons moving around, increasing the probability of one colliding with an atom of the fuel. Also, the lead coolant allows the reactor to operate near atmospheric pressure, and it doesn’t react with air or other fluids like sodium. This means that there is less need for extra safety systems which can significantly cut the costs for building the reactor. Additionally, lead’s high boiling point allows the reactor to operate at a high temperature, causing its thermodynamic efficiency to be higher than previous generations of reactors.

Nuclear Energy is the Future

We need every tool we have in this fight against climate change. That includes wind, solar, hydroelectric, and…you guessed it, nuclear. Nuclear energy is emission free and has very few consequences, and those consequences are relatively small. For example, the amount of nuclear waste produced in the US since the 1950s could fit on a football field, while fossil fuels have contributed countless tons and tons of carbon emissions into the atmosphere. Additionally, as stated before, many of these new reactors can use up this “waste” as well, minimizing that con even more.

If we want to move to carbon zero energy and a carbon zero world, we need nuclear power. Once again, nuclear energy is extremely safe and efficient, and with the technology becoming cheaper and more accessible, it is becoming more and more feasible to implement on a wider scale. If we want to fight climate change and help turn the corner, nuclear energy must be part of the conversation as we move towards a cleaner, brighter future.