nuclear-news

Will AI’s huge energy demands spur a nuclear renaissance?

Contracts with Google and Amazon could help, but bringing new types of reactor online will take larger investments — and time.

Davide Castelvecchi, Nature , 25vOct 24

Last week, technology giants Google and Amazon both unveiled deals supporting ‘advanced’ nuclear energy, as part of their efforts to become carbon-neutral.

Google announced that it will buy electricity made with reactors developed by Kairos Power, based in Alameda, California. Meanwhile, Amazon is investing approximately US$500 million in the X-Energy Reactor Company, based in Rockville, Maryland, and has agreed to buy power produced by X-energy-designed reactors due to be built in Washington State.

Both moves are part of a larger [??] green trend that has arisen as tech companies deal with the escalating energy requirements of the data centres and number-crunching farms that support artificial intelligence (AI). Last month, Microsoft said it would buy power from a utility company that is planning to restart a decommissioned 835-megawatt reactor in Pennsylvania.

The partnerships agreed by Google and Amazon involve start-up companies that are pioneering the design of ‘small modular reactors’, which are intended to be assembled from prefabricated pieces………….they still have a way to go before they become a reality.

Nature talked to nuclear-energy researchers to explore the significance and possible implications of these big-tech investments.

Could these deals spur innovation in the nuclear industry?

Building nuclear power stations — a process often plagued by complex permit procedures, construction delays and cost overruns — is financially risky, and betting on unproven technologies is riskier still…………..

 the details of the deals are murky, and the level of support provided by Amazon and Google is likely to be “a drop in the bucket” compared with the billions these start-ups will ultimately need, says physicist Edwin Lyman, director of nuclear power safety at the Union of Concerned Scientists in Washington DC. “The PR machine is just going into overdrive,” says Lyman, but “private capital just doesn’t seem ready yet to take that risk”.

Allison Macfarlane, director of the School of Public Policy and Global Affairs at the University of British Columbia in Vancouver, Canada, and former chair of the US Nuclear Regulatory Commission (NRC), says that the speed of progress in computer science raises another question. “If we’re talking 15 years from now, will AI need that much power?”

Are there safety advantages to the small modular designs?

“The smallest reactors, in theory, could have a high degree of passive safety,” says Lyman. When shut down, the core of a small reactor would contain less residual heat and radioactivity than does a core of the type that melted down in the Fukushima Daiichi disaster that followed the cataclysmic 2011 tsunami in Japan.

The companies also say that the proposed pebble-bed reactors are inherently safer because they are not pressurized, and because they are designed to circulate cooling fluids without the help of pumps (it was the loss of power to water pumps that caused three of the Fukushima plant’s reactors to fail).

But Lyman thinks it is risky to rely on potentially unpredictable passive cooling without the backup of an active cooling option. And as reactors become get smaller, they become less efficient. Another start-up company, NuScale Power, based in Portland, Oregon, originally designed its small modular reactor — which was certified by the NRC — to produce 50 MW of electricity, but later switched to a larger, 77-MW design. The need to make the economics work “makes passive safety less credible”, Lyman says.

Do small modular reactors carry extra risks?

In some cases, small modular reactors “could actually push nuclear power in a more dangerous direction”, says Lyman. “Advanced isn’t always better.”

In particular, Lyman points out that the pebble-bed designs drawn up by X-energy and Kairos would rely on high-assay low-enriched uranium (HALEU), which comprises 10–20% uranium-235 — compared with the 5% enrichment level required by most existing reactors (and by NuScale’s reactor). HALEU is still classified as low-enrichment fuel (as opposed to the highly enriched uranium used to make nuclear bombs), but that distinction is misleading, Lyman says. In June, he and his collaborators — including physicist Richard Garwin, who led the design of the first hydrogen bomb — warned in a Science article that a bomb could be built with a few hundred kilograms of HALEU, with no need for further enrichment¹.

Smaller reactors are also likely to produce more nuclear waste and to use fuel less efficiently, according to work reported in 2022 by Macfarlane and her collaborators². In a full-size reactor, most of the neutrons produced by the splitting of uranium travel through a large volume of fuel, meaning that they have a high probability of hitting another nucleus, rather than colliding with the walls of the reactor vessel or escaping into the surrounding building. “When you shrink the reactor, there’s less material in there, so you will have more neutron leakage,” Macfarlane says. These rogue neutrons can be absorbed by other atomic nuclei — which would then themselves become radioactive.

Will small reactors be cheaper to build?

The capacity to build components in an assembly line could drastically cut reactors’ construction costs. But there are also intrinsic economies of scale in building larger reactors, says Buongiorno. “Don’t believe people blindly” when they say smaller reactors will produce cheaper energy, he says: nuclear energy has a lot going for it, but “it ain’t cheap” — and that is unlikely to change significantly.

Will all of these efforts help to combat climate change?

…………….. whether building new reactors is the best way to rapidly cut emissions is debated. Macfarlane points out that solar panels and wind turbines can be deployed at a much faster rate.
https://www.nature.com/articles/d41586-024-03490-3

October 28, 2024 - Posted by Christina Macpherson | energy storage, Small Modular Nuclear Reactors