Nuclear power is known for consuming vast amounts of water for cooling, but many promising designs of Small Modular Reactors use helium instead. These High-Temperature Gas-Cooled Reactors (HTGRs) can produce more electricity per unit of fuel and power new infrastructure such as water purification and hydrogen production.
HTGRs are not new, but the latest designs improve on both earlier versions and traditional water-cooled nuclear plants by being inherently safe and even less impactful on resources and the environment.
Sourcing Helium
Helium is the universe’s second most abundant element after hydrogen, but it is rare on Earth where it is formed through the slow radioactive decay of heavy elements like uranium.
Trapped deep underground within natural gas reservoirs, helium is generally found in very low concentrations – less than 0.1%. Its extraction generally becomes profitable when it makes up 0.5%.
The journey from the ground to the tank is intensive. Crucial for weather balloons, semiconductors, MRI cooling, and SCUBA tanks, helium must be purified to levels between 99% (“balloon grade”) and 99.9999% (manufacturing semiconductors).
After pre-treating the gas to remove water and heavy molecules, the mixture is then cooled until all other gases liquefy, leaving behind pure helium.
Safe, Stable and Efficient Cooling
Traditional nuclear power plants usually use water as a coolant. These plants use nuclear fission to create heat, which boils water into steam to turn a turbine.
HTGRs use helium gas instead of water as the medium to carry heat away from the reactor core.
HTGRs were first proposed in 1944, and a working unit started producing power in 1965. Today, there are two HTGRs operating commercially in China and a research unit in Japan that is being used to produce hydrogen fuel. All three have clean safety records.
Helium has several physical advantages that contribute to making HTGR reactors inherently safe. It is chemically inert, meaning it does not react with other materials or corrode the pipes inside the reactor. This helps equipment last longer and reduces the need for complex maintenance.
It also stays in a gaseous state across a very wide range of temperatures. This makes it a coolant that will not boil away or explode in an SMR, eliminating a major risk factor.
Helium-cooled systems are also remarkably efficient as the gas transfers heat at much higher temperatures than water. HTGRs can convert a higher percentage of nuclear heat into usable electricity, achieving efficiencies far greater than traditional water-cooled reactors. This means more power is generated from every bit of fuel used.
In addition to generating electricity, this high-temperature heat can be used as “process heat”, powering secondary applications such as desalination plants and manufacturing clean hydrogen. This “cogeneration” can simplify logistics for remote industrial sites and significantly reduce their carbon footprint.
Maximum Flexibility, Minimal Impact
Traditional nuclear plants need to be near large lakes or oceans for cooling, but HTGRs do not have that limitation. This makes them ideal for remote mining sites or communities in dry or rugged locations.
Because they do not use local water, they also do not impact local waterways, minimizing their impact on local ecosystems and biodiversity.
Managing Helium
Every technology has its challenges that must be managed carefully. Helium is a limited resource, and its prices have shifted by up to 40% in recent years. New sources of helium are slated to begin operating in the coming decade, promising a more stable supply at less volatile prices.
Regardless of the amount available, helium is a critical resource for many important industries and special care must be taken to prevent its tiny molecules from leaking out.
StarCore’s HTGR uses advanced features such as specialized seals, closed-loop systems and double-walled underground silos to keep the gas circulating without escaping. Precise monitoring technology catches the smallest changes in pressure instantly. This ensures that the reactors maximize efficiency and minimize waste throughout their long lifespans.
It also uses a surprisingly small amount. A typical MRI machine needs about 212 kg of liquid helium stored inside to operate properly – StarCore only needs about 66 kg per reactor core.
Whether it is powering a mine in the arctic or providing fresh water in a desert, helium-cooled SMRs are the key to unlocking energy independence and building a safer, more versatile future.
