Mothballed nuclear plants coming back to life
29-01-2025 | Posted by Joaquín Martí
Microsoft announced on 20 September that it had struck a 20-year deal to purchase energy from a dormant nuclear power plant, Three Mile Island, the facility that experienced a partial meltdown of one of its reactors in 1979. The move, which symbolizes technology giants’ need to power their growing artificial-intelligence (AI) efforts, raises questions over how shuttered nuclear plants can be restarted safely — not least because Three Mile Island isn’t the only plant being brought out of retirement.
Palisades Nuclear Plant, an 805-megawatt facility, was shut down in May 2022. But the energy company that owns it, Holtec International, plans to reopen it in late 2025, bolstered by a US$1.5-billion conditional loan commitment from the US Department of Energy (DoE), which sees nuclear plants as a way of helping the country to meet its ambitious climate goals.
Since 2012, more than a dozen nuclear plants have been shut down in the United States, in some cases as a result of unfavourable economics. Less cost-effective plants struggled to remain profitable in states with deregulated electricity markets and widely varying prices. Three Mile Island, owned by Constellation Energy, is a prime example.
Nuclear energy, which accounts for about 9% of the world’s electricity, has seen some resurgence internationally, but is also competing with other energy sources, including renewables. After the 2011 Fukushima Daiichi disaster, Japan suspended operations at all of its 48 remaining nuclear plants, but these are gradually being brought back online. By contrast, Germany announced a phase-out of its nuclear plants in 2011 and shut down its last three in 2023.
In the United States, nuclear energy’s fortunes might be turning as technology companies race to build enormous, energy-gobbling data centres to support their AI systems and other applications while somehow fulfilling their climate pledges. Microsoft, for instance, has committed to being carbon negative by 2030.
When Palisades and Three Mile Island closed, their then-owners made legal statements that the facilities would be shut down, even though their operating licenses were still active. Three Mile Island, which will be renamed the Crane Clean Energy Center under the proposed restart, shut down its single remaining functional reactor in 2019.
Because the plants were slated for shutdown and safety checks were therefore stopped, regulators and companies must now navigate a complex licensing, oversight and environmental-assessment process to reverse the plants’ decommissioning. Safety checks will be needed to ensure, among other things, that the plants can operate safely once uranium fuel rods have been replaced in their reactors.
When these plants were decommissioned, their radioactive fuel was removed and stored, so the facilities no longer needed to adhere to many exacting technical specifications. It will be no small feat to reinstate those safety regulations. For example, at Palisades, indications of stress corrosion cracking in steam generator tubes have been found to exceed by far estimates based on previous operating history: 1,163 steam generator tubes, out of about 16,000, showed those indications.
There probably won’t be too many other restarts of mothballed nuclear plants, however, even as demand for low-carbon electricity grows. But that doesn’t mean that all of these sites will remain unused. One option is to build advanced reactors — including large reactors with upgraded safety features and small modular reactors with innovative designs — on sites where old nuclear plants once stood, to take advantage of existing transmission lines and infrastructure.
Incidentally, it does make you ponder why some countries choose to shut down their reactors or refuse to extend their operating life, while others consider reviving their decommissioned ones.
This post is largely excerpted from a Scientific American article published on October 2, 2024.
