High hopes and security fears for next-gen nuclear reactors

Fuel for advanced reactors is raising nuclear proliferation concerns.

The Verge, By Justine Calma, a senior science reporter covering energy and the environment with more than a decade of experience. She is also the host of Hell or High Water: When Disaster Hits Home, a podcast from Vox Media and Audible Originals, Jul 20, 2024

Next-generation nuclear reactors are heating up a debate over whether their fuel could be used to make bombs, jeopardizing efforts to prevent the proliferation of nuclear weapons.

Uranium in the fuel could theoretically be used to develop a nuclear weapon. Older reactors use such low concentrations that they don’t really pose a weapons proliferation threat. But advanced reactors would use higher concentrations, making them a potential target of terrorist groups or other countries wanting to take the fuel to develop their own nuclear weapons, some experts warn.

They argue that the US hasn’t prepared enough to hedge against that worst-case scenario and are calling on Congress and the Department of Energy to assess potential security risks with advanced reactor fuel.

Other experts and industry groups still think it’s unfeasible for such a worst-case scenario to materialize. But the issue is starting to come to a head as nuclear reactors become a more attractive energy source, garnering a rare show of bipartisan support in Congress.

……. Earlier this month, President Joe Biden signed bipartisan legislation into law meant to speed the development of next-generation nuclear reactors in the US by streamlining approval processes.

………….The US Nuclear Regulatory Commission (NRC) certified an advanced small modular reactor design for the first time last year. And we’re likely still years away from seeing commercial plants in action. But if the US ever wants to get there, it’ll also have to build up a supply chain for the fuel those advanced reactors would consume. The Inflation Reduction Act includes $700 million to develop that domestic fuel supply.

Today’s reactors generally run on fuel made with a uranium isotope called U-235. Naturally occurring uranium has quite low concentrations of U-235; it has to be “enriched” — usually up to a 5 percent concentration of U-235 for a traditional reactor. Smaller advanced reactors would run on more energy-dense fuel that’s enriched with between 5 to 20 percent U-235, called HALEU (short for high-assay low-enriched uranium).

That higher concentration is what has some experts worried. “If the weapons usability of HALEU is borne out, then even a single reactor would pose serious security concerns,” says a policy analysis penned by a group of nuclear proliferation experts and engineers published in the journal Science last month (including an author credited with being one of the architects of the first hydrogen bomb).

Fuel with a concentration of at least 20 percent is considered highly enriched uranium, which could potentially be used to develop nuclear weapons. With HALEU designs reaching 19.75 percent U-235, the authors argue, it’s time for the US to think hard about how safe the next generation of nuclear reactors would be from malicious intent.

“We need to make sure that we don’t get in front of ourselves here and make sure that all the security and safety provisions are in place first before we go off and start sending [HALEU] all around the country,” says R. Scott Kemp, associate professor of nuclear science and engineering and director of the MIT Laboratory for Nuclear Security and Policy.

That 20 percent threshold goes back to the 1970s, and bad actors ostensibly have more information and computational tools at their disposal to develop weapons, Kemp and his coauthors write in the paper. It might even be possible to craft a bomb with HALEU well under the 20 percent threshold, the paper contends……………………………………………………………………………………..

Aside from asking Congress for an updated security assessment of HALEU, the paper suggests setting a lower enrichment limit for uranium based on new research or ramping up security measures for HALEU to more closely match those for weapons-usable fuels.

…………………………“Unless there’s a really good reason to switch to fuels that pose greater risks of nuclear proliferation, then it’s irresponsible to pursue those,” says Edwin Lyman, director of nuclear power safety at the Union of Concerned Scientists and another author of the paper. Lyman has also raised concerns about the radioactive waste from nuclear reactors over the years. “There is no good reason.” https://www.theverge.com/24201610/next-generation-nuclear-energy-reactors-security-weapons-proliferation-risk