Can a coal state go nuclear?

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Wyoming is a coal state. It’s an oil and gas and trona and bentonite and — tenuously — uranium state. And with the help of a Bill Gates-fronted technology company, it could soon become a nuclear state.

Five months have passed since nuclear developer TerraPower and Rocky Mountain Power, Wyoming’s largest utility, revealed plans to build a 345-megawatt demonstration reactor at one of four retiring Wyoming coal plants. They’re partnering with the federal government, which will pay half the costs, up to a $1.6 billion ceiling, but that money comes with a time limit: The plant must be operational by 2028.

It’s an ambitious target. Achieving it would be groundbreaking. No U.S. nuclear project has been completed on schedule, or on budget, in decades.

Still, to communities faced with impending, irreplaceable job losses, the proposal offers a lifeline. Leaders from Glenrock, Gillette, Rock Springs and Kemmerer have all asked TerraPower the same question: “How do we make sure it’s built here?”

In short, they can’t. Enthusiasm doesn’t hurt, but as long as the infrastructure meets TerraPower’s standards, the decision comes down to factors like geology, seismology, meteorology and hydrology, in accordance with the standards of the Nuclear Regulatory Commission (NRC) — the independent federal agency that evaluates and authorizes nuclear development.

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Retirement dates are a consideration, too. Even though the nuclear facility will be built separately, the chosen coal plant must be shut down before the reactor starts up. While the Naughton and Dave Johnston coal units are already scheduled to close by 2027, Rocky Mountain Power plans to keep the Jim Bridger and Wyodak plants operating through the late 2030s.

But all four plants will close eventually, and each loss will cost local jobs — many of which the project promises to restore — and eat away at the state’s baseload electricity supply.

“There’s a need to put something on the grid following those coal plant retirements,” said TerraPower CEO Chris Levesque. “To put something on the grid that runs 24/7, that can up its power when wind and solar are curtailed.”

TerraPower believes a new generation of nuclear plants can meet that emerging need. In collaboration with fellow nuclear developer GE Hitachi, the company “reinvented what a reactor can be,” Tara Neider, senior vice president of TerraPower and the project’s director, said during a presentation last September, before the company picked Wyoming for its first plant.

“We largely started by blowing away what a reactor looks like and breaking it into its individual parts,” Neider said. “Then we started putting it back together. And nothing was considered sacred.”

Out of the partnership came a minimalist design called Natrium — the Latin word for sodium — after the liquid metal that flows through the reactor’s core. Rooted in ideas developed in the 1960s, but adapted to the modern energy market, Natrium is now poised to become Wyoming’s first-ever nuclear power plant.






Glenrock Nuclear Meeting

Chris Levesque, president and CEO of TerraPower, fields questions in July about a proposal to build the first in a new generation of nuclear power plants in Wyoming. The plant uses molten salt, which doubles as a giant battery.




A troubled history

Unlike Natrium, all operating U.S. nuclear plants are cooled with water. These commercial light water reactors fall into two main categories: Boiling water reactors and pressurized water reactors.

Inside the core of each plant, uranium-235 atoms — the only isotope of uranium able to undergo nuclear fission — are split apart, releasing heat, like other fuels do when combusted. The fission reaction is used to heat water, which turns to steam and spins a turbine to produce electricity.

Both types of light water reactors circulate water through the core. In boiling water reactors, some of the water is allowed to turn to steam; in more commonly used pressurized water reactors, the water is used to heat a secondary water system, where the steam is produced.

Nuclear reactors operate at temperatures much hotter than the boiling point of water, which must be pumped through the core at a very high pressure to prevent it from boiling away. Sodium, in contrast, is solid at room temperature, and has a relatively low melting point of 208°F — a few degrees shy of water’s boiling point — but won’t boil until it reaches 1,621°F, eliminating the need to keep the coolant highly pressurized.

Heavy piping and containment are required for high-pressure systems. In theory, the lower pressure required for sodium cooling would also come with lower costs.

Sodium reactors are no longer used in the U.S. The technology, however, has been part of nuclear development since the emergence of the industry. It cooled the first nuclear power plant to publicly supply electricity to the U.S. grid, the Sodium Reactor Experiment, which operated in California between 1957 and 1964, according to the Department of Energy. The plant was down for much of 1959 and 1960, after a coolant flow blockage caused a partial meltdown.

Sodium was used even earlier to cool the Experimental Breeder Reactor I (EBR-I), the first U.S. nuclear plant, which began operating in 1951 at what is now the Idaho National Laboratory. In 1955, a coolant flow test triggered an unexpected partial meltdown of the reactor core. EBR-I was permanently shut down in 1963.

Yet another sodium prototype, Michigan’s Fermi-I, came online in 1963. In 1966, it suffered a partial meltdown also caused by a coolant blockage. After nearly four years of cleanup, the reactor was restarted in 1970, but closed again in 1972.

In the wake of those repeated accidents, and with few more recent projects to build upon, some experts have questioned the merit of further sodium development. Just one U.S. sodium reactor has evaded major accidents.

The successor to EBR-I, the 20-megawatt Experimental Breeder Reactor II (EBR-II), began operating in 1965. This time, researchers’ intentional efforts to force a meltdown — including a simulation of total cooling pump failure — were unsuccessful, demonstrating the efficacy of built-in passive cooling systems. The plant was decommissioned in 1994.

Only Russia has demonstrated a commercial-scale sodium fast reactor that’s still operating today. The U.S., meanwhile, has stuck with trusted light water reactors. But in an electricity market dominated, increasingly, by cheaper natural gas and renewables, and with nuclear’s reputation tarnished by high-profile accidents at Three Mile Island and Fukushima, the established technology is struggling.

“Nuclear companies and nuclear projects have not embraced innovation and new technology as much as they could,” Levesque said.

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