US Big Tech Also Joins... 4th Generation SMR Market Race [C Tech Now]

Experienced K-Wonjeon Contract Acquisition Expected

A bird's-eye view of NuScale Power's Small Modular Reactor (SMR) power plant. Provided by NuScale Power

As the second term of the Donald Trump administration approaches, interest in Small Modular Reactors (SMRs) is heating up. At the same time, major U.S. big tech companies such as Google and Amazon are racing to secure SMRs to supply the power needed for their artificial intelligence (AI) data centers. There is also growing optimism that domestic companies, leveraging their extensive experience in constructing large nuclear power plants, will be able to win SMR projects.

What is an SMR? ... Safer and More Versatile

SMR (Small Modular Reactor) refers to small to medium-sized modular reactors with lower output compared to large nuclear power plants. Reactors with a capacity of 1000 megawatts (MW) or more are classified as large nuclear power plants, while those with 300 MW or less are classified as SMRs. SMRs have simpler designs compared to large nuclear plants and can be prefabricated in factories and installed on-site, which reduces construction time and costs. While building a large nuclear power plant can take over 10 years, an SMR can be completed within 3 years. Being smaller, SMRs are considered safer than large nuclear plants and are expected to be used not only for power generation but also for heat supply, seawater desalination, hydrogen production, and other diverse applications.

When neutrons collide with uranium-235, the nuclear fuel, nuclear fission occurs, releasing enormous energy. Nuclear power plants use this energy to generate steam, which then drives turbines to produce electricity.

The pressurized water reactor (PWR) type, widely used internationally including in South Korea, uses water (light water) to cool the reactor. It is called a pressurized water reactor because pressure is applied to raise the boiling point of the water. The PWR type nuclear power plant houses equipment such as the reactor core where nuclear fusion occurs, control rods that regulate output, pressurizers, steam generators, cooling pumps, and cooling pipes all within a single containment building. Including the turbines and generators located outside the containment building, the scale is enormous.

SMRs reduce the scale by placing the equipment found in the containment building of large nuclear plants into a single sealed container (containment vessel) and manufacturing it in modular form at factories. The cooling system is the most significant difference between SMRs and large nuclear plants.

Large nuclear plants use cooling water to cool the heated reactor, but if a disaster disrupts the cooling system, it can lead to an accident. In the 2011 Fukushima nuclear accident in Japan, the reactor was flooded, causing a power outage, and the cooling pumps stopped working, which directly caused the core temperature to rise rapidly.

In contrast, PWR-type SMRs have enhanced safety by applying a passive safety system that uses natural convection to cool the reactor. Because fewer parts and equipment are needed for the cooling system, it is also easier to reduce the size. The U.S. NuScale Power’s 77 MW SMR, currently considered the most advanced in commercialization, is designed to be 23 meters tall, 4.6 meters in diameter, and weigh 700 tons.

Because SMRs are smaller and safer than traditional large nuclear plants, they can be built near demand centers. The enormous thermal energy generated from nuclear fission can be used for district heating, industrial processes, and seawater desalination. Additionally, if SMRs are used to produce hydrogen with their electrical energy, hydrogen prices could be significantly lowered, accelerating the transition to a hydrogen society.

Big Tech Companies Race to Invest in 4th Generation SMRs

According to the International Atomic Energy Agency (IAEA), as of 2022, over 80 types of SMRs are under development worldwide. NuScale accelerated its SMR design by basing it on the existing 3rd generation PWR nuclear plants. The PWR technology is mature, accounting for about 90% of reactors worldwide. NuScale’s SMR completed its design certification review by the U.S. Nuclear Regulatory Commission (NRC) in 2020. South Korea’s innovative SMR (iSMR), developed as a national project, is also based on the PWR type.

Recently, SMRs based on 4th generation nuclear reactors have attracted attention. The Generation IV International Forum (GIF), composed of nuclear experts from 14 countries including South Korea, the U.S., Canada, France, the U.K., China, and Japan, has selected future reactors that improve safety and economic efficiency compared to existing nuclear power.

These include Gas-Cooled Fast Reactor (GFR), Very High Temperature Reactor (VHTR), Molten Salt Reactor (MSR), Lead-Cooled Fast Reactor (LFR), Sodium-Cooled Fast Reactor (SFR), and Super Critical Water Cooled Reactor (SCWR). These reactors address safety and nuclear waste disposal issues that have been obstacles to nuclear expansion, thereby increasing public acceptance.

Recently, U.S. big tech companies investing in or signing power supply contracts for AI data centers are mainly focusing on SMRs based on 4th generation reactors. The 4th generation SMRs are expected to be commercialized around 2030, when power demand for AI data centers surges.

U.S. nuclear power company TerraPower is holding a groundbreaking ceremony for an SMR demonstration power plant in Wyoming in June 2024. Photo by TerraPower

TerraPower, a U.S. company well known for investment by Bill Gates, adopts the sodium-cooled fast reactor method. In South Korea, SK and HD Hyundai have invested in TerraPower. In June last year, TerraPower began construction of the 345 MW 'Natrium' reactor using a sodium-cooled fast reactor in Wyoming. HD Hyundai, also an investor in TerraPower, is responsible for manufacturing the cylindrical reactor vessel for this project. Doosan Enerbility participates as the main equipment supplier. Oklo, invested in by Sam Altman, founder of AI company OpenAI, is also conducting the 'Aurora' project, an SMR based on a sodium-cooled fast reactor.

The sodium-cooled fast reactor uses liquid sodium as the reactor coolant and is a fast neutron reactor (fast reactor). Sodium has a high boiling point of 883°C, so unlike pressurized water reactors, it does not require maintaining high pressure to artificially raise the boiling point. A fast reactor uses fast neutrons for nuclear fission reactions.

In pressurized water reactors, water is used as a moderator (a substance that slows down fast neutrons generated during the nuclear fission process to thermal neutrons to facilitate fission). In contrast, fast reactors utilize fast neutrons as they are to produce plutonium-239, which undergoes fission more readily. Fast reactors also have the advantage of being able to use natural uranium-238, which accounts for 99% of natural uranium.

Kairos Power, a U.S. nuclear startup that signed a power purchase agreement with Google in October last year, is developing a molten salt reactor. Kairos Power is investing $100 million in Oak Ridge, Tennessee, to build a demonstration reactor called 'Hermes 2,' aiming for operation in 2027. The reactor that Kairos Power will use to supply electricity to Google is expected to be operational around 2030 to 2035.

Molten salt reactors use molten salts (fluoride or chloride compounds heated to a liquid state) as coolant. Nuclear fuel is dissolved together in the molten salt, serving as both fuel and coolant. The molten salt mixed with fuel has a melting point of 400?500°C and a boiling point of 1400°C, and if leaked externally, it solidifies immediately, fundamentally preventing radioactive material leakage. Integrating fuel and coolant allows the containment vessel size to be reduced.

X-energy, which Amazon announced investment in last October, is developing an SMR based on the High Temperature Gas-Cooled Reactor (HTGR) method. X-energy’s project consists of four 80 MW reactors totaling 320 MW. Amazon plans to purchase more than 5 GW of X-energy’s SMRs by 2039. Doosan Enerbility, DL E&C, and KEPCO KPS from South Korea are participating in X-energy’s SMR project.

Reactors that use helium gas as coolant and graphite as moderator are collectively called high-temperature gas-cooled reactors. Depending on the reactor temperature, they are classified as Very High Temperature Reactors (VHTR) or HTGRs, but the basic principle is the same. Helium is an inert gas that is chemically very stable, so there is no concern about corrosion of the reactor and a lower risk of radioactive material leakage.

The nuclear fuel used in high-temperature gas-cooled reactors is called TRISO (Tri-Structural ISOtropic coated fuel). TRISO consists of spherical nuclear fuel particles about 0.5 mm in diameter coated with ceramics such as pyrolytic carbon and silicon carbide, forming spherical particles about 1 mm in diameter. TRISO fuel is loaded into the reactor either as chalk-shaped rods inserted into graphite blocks or as pebble-shaped fuel elements. TRISO-based fuel has excellent safety due to its structure, which greatly reduces the possibility of fission product leakage. High-temperature gas-cooled reactors can reach temperatures up to 950°C, allowing this heat to be used in various industrial processes.

While the U.S. Accelerates 4th Generation Reactors... South Korean Parliament Cuts Budget

As SMRs are expected to change the paradigm of the future nuclear power market, governments worldwide are actively pursuing next-generation SMR development. Nuclear power countries such as the U.S., France, the U.K., Canada, Japan, Russia, China, and Argentina are actively promoting SMR development and commercialization.

In particular, the U.S. Department of Energy supports SMR companies through the Advanced Reactor Demonstration Program (ARDP) to demonstrate proposed designs by 2030 or to help resolve anticipated design and operational challenges in advance. In 2020, the DOE announced initial ARDP support for TerraPower and X-energy, providing each with $80 million. Kairos Power was also selected for ARDP and is receiving $303 million over seven years.

Tsinghua University in China completed a 10 MW pebble-type high-temperature gas test reactor in 2000 and conducted demonstration tests, based on which the HTR-PM high-temperature gas-cooled demonstration reactor was constructed in Weihai City in 2021. The Japan Atomic Energy Agency (JAEA) is conducting hydrogen production demonstration research using the HTTR high-temperature gas-cooled test reactor.

South Korea is focusing on research and development of sodium-cooled fast reactors and high-temperature gas-cooled reactors. Sodium-cooled fast reactors are being studied as part of spent nuclear fuel treatment technology because they can use plutonium-239, a highly toxic long-lived nuclide in spent fuel, as fuel and convert it into short-lived stable nuclides. The Korea Atomic Energy Research Institute is also developing nuclear hydrogen production technology using high-temperature gas-cooled reactors in preparation for the hydrogen economy era.

However, compared to overseas countries that have moved beyond demonstration to constructing commercial reactors, domestic development is considerably slower. In June last year, the Ministry of Science and ICT approved the 'Technology Development and Demonstration Promotion Plan for Securing Next-Generation Nuclear Power' at the National Science and Technology Advisory Council. According to the government roadmap, the sodium-cooled fast reactor will begin design and site surveys from 2025, and the high-temperature gas-cooled reactor will start design and site surveys from 2024, with commissioning planned for 2036. To this end, a Korean-style Advanced Reactor Demonstration Program (K-ARDP), modeled after the U.S. ARDP, will also be introduced.

In July last year, the Ministry of Science and ICT announced the launch of a public-private joint next-generation reactor development project with an investment of 45.5 billion won over four years. This project involves the Korea Atomic Energy Research Institute, POSCO E&C, Daewoo Construction, Smart Power, SK Ecoplant, Lotte Chemical, and other companies working together to complete the basic design of an indigenous high-temperature gas-cooled reactor and comprehensive plant design by 2027.

This year, the Ministry of Science and ICT planned to promote a sodium-cooled reactor demonstration project through the 'Public-Private Joint Advanced Reactor Export Infrastructure Establishment Project,' but it is at risk of being scrapped. This is because the National Assembly cut the related budget from 7 billion won to 700 million won during the government budget review in December last year.