An accelerator-based system developed in the US aims to convert spent nuclear fuel, reducing its radioactive lifespan from 100,000 years to 300 years and generating additional electricity from the process.
The necessity for spent nuclear fuel to remain radioactive for tens of thousands of years and to be safely stored has been one of the most significant obstacles to nuclear energy until now. However, important breakthroughs are being made in this field recently. A new study conducted in the US aims to transform spent nuclear fuel from a permanent burden into a reusable energy source.
Two critical projects underway at the US Department of Energy's Thomas Jefferson National Accelerator Facility are focusing on making "Accelerator-Driven Systems" (ADS) technology more viable. The goal is to both generate additional carbon-free electricity from spent fuel and dramatically shorten the radioactive lifespan of the waste.
Particle Accelerators at the Core of the Technology
Particle accelerators are at the core of ADS technology. The system triggers a process called "spallation" by sending high-energy protons to a target such as liquid mercury. This collision releases a large number of neutrons. The liberated neutrons interact with long-lived and undesirable isotopes within the nuclear waste, converting them into shorter-lived and less dangerous elements. This process is called "transmutation." While untreated spent fuel can remain hazardous for approximately 100,000 years, it is stated that this period could be reduced to about 300 years when separated and recycled with ADS. This signifies a radical change in the waste management equation.
Furthermore, the process does more than just reduce waste. The high heat generated during spallation and subsequent nuclear reactions can also be used to produce electricity. This means the system both "burns" the waste and provides additional energy to the grid, transforming ADS from merely a waste disposal technology into a potential energy generation platform.
However, for the technology to be commercially viable, two major technical hurdles must be overcome: efficiency and power requirements. Traditional particle accelerators require extremely low temperatures to achieve superconductivity, which translates to massive, expensive cryogenic cooling systems. The Jefferson Lab team is attempting to solve this problem by coating the inner surface of accelerator cavities, made from pure niobium, with tin. These niobium-tin coated cavities can operate at higher temperatures, allowing the use of standard commercial cooling systems and significantly reducing costs. A more complex design is also being developed, aiming for higher neutron production efficiency.
The second important aspect is the power source feeding the beam. Researchers are trying to adapt magnetrons, also used in microwave ovens, for ADS. The goal is to efficiently provide the approximately 10 megawatts of power required to operate the system. The most critical challenge here is ensuring that the frequency of the generated energy perfectly matches the accelerator cavities. The target frequency for this system is 805 megahertz. In collaboration with Stellant Systems, advanced magnetron prototypes capable of reaching high power thresholds are being developed. The early involvement of industrial partners like RadiaBeam and General Atomics could help accelerate the technology's transition from the laboratory to commercial production.
The long-term goal of the program is to enable the recycling of all commercial nuclear fuel stock in the US within the next 30 years. According to researchers at Jefferson Lab, the main challenge is to elevate the technological readiness level of current accelerator science to the level required for this specific application. If successful, the nuclear waste problem could transform from an inseparable and intractable byproduct of energy production into a controlled and productive resource.
0 Comments: