You can’t say that nuclear power is back, because it never really went away. It’s just been quiet, refining new designs and technologies. Now it’s ready to re-introduce itself.
Right now, China is building 30 new nuclear power plants. Russia’s building 10 and Qatar four. Oil-rich Saudi Arabia has plans to put up 16.
Most of these plants, like Westinghouse’s next-generation AP1000 design, are tweaks on the old pressured-water reactor idea. In those facilities, uranium fuel rods created boiling water, generating steam to turn turbines, which generate electricity.
To cool the uranium fuel rods, new water circulated under high pressure, like a car’s radiator system. Water under pressure has a high boiling point; without the added pressure, the coolant water would also boil to steam and be unable to take the heat away from the fuel rods.
This pressure is that reactor’s design weakness. Pressurized water can weaken or corrode safety seals and cause leaks, letting the fuel rods heat up to dangerous China Syndrome levels. Excessive heat can create flammable hydrogen gas and the plant can explode, Fukushima-style.
Scientist Ian Scott’s idea wasn’t to tweak pressurized water reactors but to make them obsolete.
He’s revived an old concept from the 1950s called the molten salt reactor or MSR. He’s simplified how it works and is getting ready to test the new design in the Canadian province of New Brunswick.
In an MSR, nuclear fuel is part of a lava-like fluid of metal salts traveling in pipes. The heat from these salts is transferred to a separate set of pipes holding non-nuclear salts. These “clean” salts are pumped to a boiler, where water is turned into steam to run electric generators.
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The MSR’s advantage is that, in theory, it can’t meltdown or blow up. MSR swaps high-pressure gases for molten salts that travel around the reactor at normal atmospheric pressure. If for any reason the plant fails and the electricity running the facility shuts off, the rising heat melts a plug and the molten salt then drains down into the reactor core. There, it solidifies, keeping the uranium rods from overheating. So, an accident at an MSR won’t blow, spewing radioactive steam into the atmosphere or flooding toxic water into the sea, as happened at Fukushima.
Unlike a pressurized water reactor, which needs intensified or “enriched” uranium for fuel, MSRs can use natural un-enriched uranium. Better yet, they also can be fueled by “spent” uranium rods from older reactors, responsibly recycling them. Currently, spent fuel is stored in ponds, caves and mineshafts in “casks” where they need thousands of decades to neutralize.
Now, this toxic waste could fuel a new generation of safer nuclear plants. An MSR facility can coax as much as 30 times as much energy from a lump of uranium than an old-style pressurized water reactor could.
Scott’s MSR, which he calls a “stable salt reactor,” uses no pumps to circulate the salts. Heat from the fuel tubes rises by natural convection to boil water and run turbines. The design is simpler and, therefore, cheaper than many other new design reactor contenders.
He’s formed a company called Moltex Energy, signing a deal to expand a nuclear research center in New Brunswick. The agreement calls for Scott to build a stable salt reactor at the province’s Point Lepreau nuclear plant site before 2030.
Other start-ups working on MSR designs include Boston-based Transatomic Power; Seaborg Technologies, a Danish company; and Terrestrial Energy, a Canadian firm that recently signed a deal with a consortium of 27 utility companies in the northwest US to explore building an MSR on the grounds of the federal Idaho National Laboratory.
But big isn’t the only way to build nuke plants. More than 40 ventures around the world are completing designs of “small, modular reactors,” or SMRs that are factory-built and delivered to a site (such as a mine or a military operating base), and then hauled away when it’s no longer needed.
For example, several US government agencies have teamed to produce an SMR they call “Kilopower.” The intent is to use it to power a mission to Mars and, perhaps, an eventual manned base on the planet.
SMRs also can supplant conventional power stations. Individual modules can be connected to meet most levels of demand. Individual modules can later be disconnected and removed, one by one, if demand falls.
Giants like Mitsubishi Heavy Industries and Holtec International, which just signed a development deal with the government of Ukraine, and young companies such as NuScale Power in Oregon are vying for a piece of the SMR market. NuScale’s is the first SMR design to pass the US Nuclear Regulatory Commission’s first review phase.
Flibe Energy in Alabama hopes to combine SMRs with a molten salt fuel system, doing it with thorium instead of uranium. Thorium is a mildly radioactive metal found with deposits of rare earth elements. It produces enough heat to run a reactor and is cheaper and more plentiful than uranium. When spent, most of its waste decays to a harmless state in mere decades, instead of tens of millennia.
Thorium also can’t meltdown, blow up, or be used to make bombs.
India, with some of the world’s largest thorium supplies, plans to test a thorium reactor within ten years. China, Russia, and the Netherlands are also eagerly pursuing this innovative technology. In the US, thorium remains classified as a toxic waste because it’s a radioactive byproduct of rare earth mining.
Therefore, its development as a power source here has been limited to lab experiments. TJ
With the world’s energy demand rising in parallel with cries to end fossil fuel use, nuclear power enthusiasts believe their time has come. Pressurized water reactors will continue to serve as the main form of nuclear generation, while MSRs and alternative forms of nuclear fuel, such as molten salts and thorium are tested and improved.
Nevertheless, nuclear’s future remains more problematic than its recent breakthroughs in technology would indicate. Public concerns about safety, from uranium mining to A-bomb making capacity, to facility operation and nuclear fuel disposal remain perpetual concerns. Meanwhile, solar, wind, and other forms of benign renewable energy, coupled with home batteries for dispersed storage, will become established as the standards for safe, reliable power.
However, the emergence of new nuclear fuels and smaller designs will make nuclear the option of choice for energy-intensive industrial operations, such as Saudi Arabia’s plans for massive desalination of sea water, in ocean-going vessels, and for trips to other planets.