The U.S. Department of Energy is pouring money into keeping America's aging nuclear reactors operating and laying the groundwork for a future nuclear energy industry.  Nuclear power remains the leading single zero-carbon source of electricity in the United States.  Here are five goals the Department of Energy is spending money on.  

Advanced theoretical research  

A grant announced by the US government will pay $12m to scientists at national laboratories across the US to conduct advanced research into problems on the fringes of nuclear physics.  

According to an Energy Department statement, the five funded projects "cover topics such as the three-dimensional internal structure of nucleons, the singular states of quarks and gluons, the microscopic properties of quark-gluon plasmas, and neutrino and nuclear interactions.  

Although the research is advanced and largely theoretical, it has the potential to open up a wide range of practical applications.  

"Advances in nuclear physics provide important new insights into the nature of our world, as well as new applications in the fields of national security, energy, health and space exploration," Holman, deputy director of science for nuclear physics, said in a statement.  

Any such advance would require a "rigorous theoretical framework" to help scientists drive the next generation of research with practical benefits.  "Holman added.  

These would include "exploring additional clean energy options and new applications in nuclear medicine and industry".  

Train nuclear power engineers  

The Energy Department is also funding universities to educate "the next generation of nuclear safety workers."  Five million dollars will go to three state universities to help them set up courses to train electrical engineers to work in nuclear reactors.  

The joint project, which brings together the University of Texas at El Paso, the University of New Mexico and North Carolina Agricultural and Technical State University, will train students to design components that can operate in the extreme environment inside a nuclear reactor.  

"We are at an extraordinary point in time where both industry and government recognize the urgent need to increase the electrical engineering workforce," Reyes, a professor of electrical engineering at the University of Texas, said in a statement.  

Reyes added that job training needs to be expanded "to stimulate growth in domestic electricity demand in areas such as chip manufacturing, transportation electrification, aerospace systems and advanced electronic packaging".  

Keep the old plant running  

Infrastructure legislation passed earlier this year contains $6 billion in civilian nuclear credits to help keep nuclear plants operating that would otherwise be replaced by fossil fuel plants.  

The Department of Energy made its first payment last month, spending $1.1 billion to keep the Diablo Canyon power plant in Southern California operating.  

The plant, which has become the focus of a public battle over the fate of nuclear power in the "two-carbon" era, had been set for phased retirement by 2025.  Local officials praised the grant.  

"In the face of record heat waves and a growing climate crisis, there is too much at stake for us to choose to step back in our fight to get rid of polluting fossil fuels altogether," lawmaker Salud Carbajal said in a statement.  

According to the Department of Energy, if that plant shuts down too, 13 other plants that could have been used have been shut down early in the past decade.  

The Department of Energy will begin accepting applications for the next round of civilian nuclear power credits in January 2023.  

Establish a nuclear fuel supply chain  

Officials announced in November that the Energy Department was spending $150 million to produce nuclear fuel essential for advanced reactors.  So-called high-enriched low-enriched uranium fuel, or HALEU, is much more enriched uranium than the nuclear fuel used in current reactors, but it is only low-enriched compared to the kinds of enriched uranium used in nuclear weapons.  

Because of its importance to smaller, more efficient nuclear reactors, the Energy Department estimates that the United States will need about 40 tons of highly enriched uranium a year by the end of the century.  

"Reducing our dependence on hostile countries for HALEU fuel and building our domestic supply chain will allow the United States to develop our advanced reactors and provide more clean, affordable electricity to Americans," Energy Secretary Jennifer Granholm said in a statement.  

The money will go to the American Centrifuge Operating Company in Maryland to pay for the development of six centrifuges capable of producing about a ton of highly enriched uranium a year, enough to meet urgent US needs.  

The Energy Ministry sees it as part of a larger drive to create a domestic HALEU industry.  

Granholm said, "This demonstrates the Department's commitment to working with industry partners to jump-start commercial-scale HALEU production to create more clean energy jobs and ensure that the benefits of nuclear power are available to all Americans.  

Catching up with nuclear fusion  

The Department of Energy announced $47 million for fusion research in October.  Unlike fission, fusion energy is produced by forcing atoms together rather than splitting, a process that does not release radioactive contamination.  

But with the extreme heat and pressure needed to drive atomic fusion, fusion is still a theoretical energy source, not practical.  

At the superheated temperatures and pressures required for nuclear fusion, the gas turns into plasma, which is extremely difficult to control.  

"We can't just put it in a container because it's going to melt whatever it touches," says Eugenio Schuster of Lehigh University.  He has received $1.75 million to work with researchers on the issue.  The money helps pay for collaborative experiments by American and international scientists at research "tokamak" sites in China, the European Union and South Korea.  

The most promising solution to this problem is a doughnut-shaped reactor in which a rotating magnetic field contains growing fusion reactions.  These magnetic fields "create an invisible bottle to hold it in and prevent these charged particles from escaping," Schuster added.  

Schuster is based at ITER, an international European test reactor.  There, scientists aim to "generate 10 times more energy than is needed to operate," he said.  "Everyone in the fusion community is working directly or indirectly for ITER".  

Other fusion funding will support American researchers conducting experiments at EAST and KSTAR in South Korea -- both "long-pulse devices" that are more advanced than existing US schemes.  

Working at these overseas research facilities "will help us develop research from these superconducting tokamak devices so that eventually we can build a long-pulse reactor-grade device in the United States," Schuster said.