Next-generation nuclear reactors have renewed debate over whether their fuel can be used to make bombs, jeopardizing efforts to prevent the spread of nuclear weapons.
Nuclear reactors produce electricity without emitting climate-changing greenhouse gases. Unlike solar and wind energy, whose output fluctuates depending on the weather and time of day, nuclear reactors provide a constant source of electricity, similar to gas and coal power plants. The United States has introduced new legislation to speed up the development of next-generation nuclear reactors by streamlining licensing procedures. New generation reactors are smaller and modular to make them cheaper and easier to build than old-style nuclear power plants. In addition to electricity generation, small reactors can also be used to generate high-temperature heat for industrial facilities.
The US Nuclear Regulatory Authority (NRC) last year for the first time authenticated an advanced small modular reactor design. We are probably still years away from seeing commercial power plants in operation. But if the US is ever to achieve this goal, it will also need to build the supply chain for the fuel that these advanced reactors would consume.
Today’s reactors usually run on fuel made from the uranium isotope U-235. Naturally occurring uranium has a fairly low concentration of U-235; in the case of conventional reactors, it is usually “enriched” to a 5 percent U-235 concentration. The smaller, modern reactors use fuel with a higher energy density, enriched with 5-20 percent U-235, so-called HALEU (High-Assay Low-Enriched Uranium) would work. It’s this higher concentration that has some experts worried. “If HALEU is proven to be a weapon, even a single reactor would raise serious safety concerns,” says a group of nuclear experts and engineers published in the journal Science. in analysis (one of whose authors is one of the first hydrogen bombs its designer).
They say the United States has not adequately prepared for the worst-case scenario and are calling on Congress and the Department of Energy to assess the potential safety risks associated with fuel for advanced reactors. Other experts and industry groups still believe that such a worst-case scenario is not possible. The question is becoming more and more relevant because nuclear reactors are becoming an increasingly attractive source of energy, and in the US Congress it is rare bipartisan support he enjoys them.
Fuel with a concentration of at least 20 percent is considered highly enriched uranium, which can potentially be used to develop nuclear weapons. According to the authors, with the emergence of HALEU designs reaching 19.75 percent U-235, it is time for the United States to think hard about how safe next-generation nuclear reactors are from malicious use. “We need to make sure that all the safety and security measures are in place before we go out and start deploying (HALEU) across the country,” writes R. Scott Kemp, associate professor of nuclear sciences and engineering and MIT nuclear safety director of his laboratory.
Small modular reactors address the current drawbacks of nuclear power plants: they can be mass-produced, cheap, and quickly installed
This 20 percent threshold dates back to the 1970s – write Kemp and his co-authors. According to the study, it may even be possible to make a bomb with HALEU well below the 20 percent threshold. Fortunately, that would still be incredibly difficult. “This is not a simple theft,” says Charles Forsberg, a senior researcher at MIT and a former corporate associate at Oak Ridge National Laboratory. He says a group would have to steal years of fuel from a small advanced reactor to make the bomb described in the study. Even with a working weapon design, he says, it would take a sophisticated team of at least several hundred people to convert the fuel into uranium metal and thus carry out all the steps necessary for a working weapon.
“Unless they are much better than me and the colleagues I work with, a subnational group (like a terrorist group) doesn’t stand a chance,” Forsberg says. An enemy nation would have more capacity than a small group, but he still doesn’t believe that It would be worth it to them. With their resources, they could easily start building a plant that would produce weapons-grade uranium, typically over 90 percent enriched. It would be a more credible risk if another country started manufacturing and stockpiling HALEU for future reactors. – but actually with more nefarious intentions. Once they have enriched uranium for HALEU, they have already built the capacity to achieve weapons-grade uranium. “That is our concern with any nation-state that decides to produce HALEU,” says Forsberg. . “If you have already taken a few steps, you are already closer to the realization”.
In addition to asking Congress to update the safety assessment of HALEU, the document recommends setting a lower enrichment limit for uranium based on new research, or enhancing safety measures for HALEU to more closely match those for weapons-grade fuels.
Contrary to the authors of the Science study, Forsberg believes that adequate precautions are already in place to keep next-generation nuclear reactors and HALEU safe. According to him, the security risks have been well known for decades, although most of them are secret information. In part, this also makes it difficult to dispel fears. “The views of the authors of the study do not contain any new information that should discourage the development and deployment of HALEU beyond the requirements already strictly defined by international regulatory bodies,” said Jennifer Uhle, the Nuclear Energy Institute’s vice president for technical and regulatory services. .
After the Chernobyl disasters in 1986 and Fukushima in 2011, some of the fears surrounding nuclear power have faded because of the need to find energy sources that do not contribute to climate change. But not everyone is convinced, and safety concerns about HALEU echo other issues raised by critics of nuclear power. “Unless we have a really good reason to switch to fuels that pose a higher risk of nuclear proliferation, it’s irresponsible to introduce them,” says Edwin Lyman, director of nuclear safety at the Union of Concerned Scientists and another author of the study. concerns about radioactive waste from nuclear reactors formulated. “There’s no good reason to build them.”
Source: sg.hu
