Generation IV Nuclear Reactors Are Coming

Generation IV nuclear reactors are a class of newer reactor designs currently under development for commercial applications. They operate at high neutron energies, use carbide and nitride fuels, and produce electricity without discharging into the air. These reactors are the most environmentally friendly of the nuclear power plants, but they do come with their share of challenges.

Gen IV reactors produce electricity without discharging it into the air.

The new generation of nuclear reactors can generate electricity without releasing any harmful gases into the atmosphere and are therefore a viable alternative to conventional coal-fired plants. The EM2 is a 500 MWt reactor with a power capacity of 240 megawatts. It runs at 850 degrees Celsius and can be fuelled with used PWR fuel, depleted uranium, or low-enriched uranium. The EM2 is based on the Framatome Fast Modular Reactor (FMR), a 50-megawatt nuclear power reactor.

The US Nuclear Regulatory Commission and the French Nuclear Safety Authority have launched a Multinational Design Evaluation Program (MDEP), which involves countries committed to developing and building these new nuclear reactors. It has chosen six reactor technologies to meet the increased demand for electricity, resist the diversion of materials for weapons proliferation, and protect against terrorist attacks. These reactors will require about $6 billion to develop and will be commissioned by the United States, Japan, and France.

They operate at high neutron energies.

The world’s current nuclear fleet is more than 30 years old. Twenty-five percent of these reactors are older than 40 years, and operators are trying to extend their operational lives through long-term investment. The Fukushima nuclear disaster spurred the adoption of new standards for reactors. Gen IV reactors must produce more fuel than they consume, and they must destroy any long-lived radioelements they create during operation.

Today, the vast majority of nuclear reactors employ a thermal neutron-emission spectrum. This means that the fast neutrons released during atomic fission are slowed down to low energy, and the thermal neutrons will collide with light atoms, such as hydrogen in water. Unlike traditional nuclear reactors, fourth-generation reactors use only uranium-238 fuel to operate. To make the reactor more efficient, vast reserves of natural uranium-235 are set aside for this purpose.

They use nitride or carbide fuels.

While nitrides are more flammable and have better thermal conductivity, carbides are less volatile. However, they do have issues with carbon and oxygen impurities. Carbide fuel is pyrophoric and has low plasticity, and its reprocessing processes are problematic. Carbides have a high carbon content and may react with hydrogen.

The Generation IV systems aim to achieve a performance improvement, new uses for nuclear energy, and more sustainable nuclear materials management. High-temperature systems could be used for hydrogen production and efficient process heat applications. Advanced fuels and coolant technologies are required for these reactors, and a closed fuel cycle will increase their sustainability, reducing waste generation and uranium resource requirements. Several countries are working on these technologies.

The NRC has called for a global code for Generation IV nuclear reactors, which will help harmonize regulatory standards for the design. A typical design code is also essential since it allows governments to ensure that new reactors meet the exact safety requirements. Various countries use this code as part of the MDEP, which shares information with international nuclear regulators.