Before an SMR Reaches the Grid

💧Cooled by water or by salt#

Light-water and non-light-water designs

Samsung C&T explains that conventional light-water SMRs use water as coolant, so they must run at high pressure to keep it liquid at high temperature. Next-generation SMRs are designed to use non-water coolants such as molten salt or sodium and run hot at low pressure. The company says it expects that high-temperature heat to serve industrial heat supply and hydrogen production as well as power generation.

BWRX-300#

A 300 MW-class boiling water reactor

GE Vernova Hitachi (GVH) developed this 300 MW-class SMR from its existing boiling water reactor technology. A boiling water reactor boils water inside the reactor and uses the steam to turn a turbine. According to Samsung C&T, the design is being built at Darlington in Ontario, Canada, as the first commercial SMR in the Western world, and an operating license application was filed there in April.

KP-FHR#

Molten fluoride salt coolant and TRISO fuel

Kairos Power is commercializing a fluoride salt-cooled, high-temperature reactor. Kairos says the reactor combines TRISO particle fuel with molten fluoride salt coolant and is designed as a modular plant for multi-unit deployment. Samsung C&T says the agreement extends its business from light-water SMRs to next-generation non-light-water designs.

📜The construction permit comes first#

The first non-water reactor permit in half a century

In 2023 Kairos Power received the first U.S. construction permit for a non-water-cooled reactor to be issued in more than 50 years. Samsung C&T likewise describes the project as the first non-light-water reactor in some 50 years to win construction approval from the U.S. Nuclear Regulatory Commission (NRC). The construction permit for the Hermes 2 demonstration plant followed in December 2024.

Groundbreaking in Oak Ridge#

April 2026, with Energy Department support

Hermes 2 is a demonstration plant being built in Oak Ridge, Tennessee, where Kairos Power broke ground in April 2026. The U.S. Department of Energy supports the development and demonstration of the technology through an Advanced Reactor Demonstration Program risk reduction award, and Kairos says substantial private investment complements it.

Why schedules slip#

Samsung C&T's answer in July

Asked on its July conference call about delays in overseas nuclear projects, Samsung C&T said there have been cases where licensing, financing and policy decisions in each country shifted schedules beyond market expectations. It added that, given growing power demand and the push for carbon neutrality, it still judges that growth in both large reactors and SMRs will continue.

🏗️A 50 MW demonstration reactor#

Hermes 2

Hermes 2 is a grid-connected reactor with an electrical output of 50 MW. Kairos Power says the demonstration plant is meant to reduce technical, licensing, manufacturing and construction uncertainty for the full-size commercial plants that will follow. The electricity it produces goes to the grid of the Tennessee Valley Authority (TVA).

Target year of operation#

2031 in Samsung C&T's release

In its September 22 press release, Samsung C&T gave 2031 as the target for operating the Hermes demonstration reactor. Kairos Power's September 21 release gave the April 2026 groundbreaking and the 50 MW scale but no year of operation. Of the two releases, the one that states a target year comes from the investor.

Romania starts with one unit#

A 77 MW module to prove performance

NuScale's Romanian SMR project also begins with a first step of a demonstration character. According to Samsung C&T's conference call, Romania's nuclear power company is considering running one 77 MW module commercially first to confirm its performance, then building the remaining five modules in stages. Samsung C&T said it does not expect its own scope or scale of participation to change much if that happens.

🔌Who buys the power#

The Google agreement and Sweden's targets

A reactor needs someone to buy its electricity. For Hermes 2, that role falls to Google: the plant's power is supplied under a multi-plant development agreement Kairos Power signed with Google. In Sweden, the government has set targets for new nuclear capacity, and nuclear companies such as Studsvik lead individual projects within them.

The multi-plant agreement with Google#

50 MW to the TVA grid

Kairos Power says Hermes 2 will supply 50 MW of electricity to the TVA grid under its multi-plant development agreement with Google. Samsung C&T's conference call made a similar point: global big tech companies and cloud providers are expected to keep moving to lock in power from large reactors and SMRs to secure stable carbon-free supply.

Sweden's new nuclear targets#

2.5 GW by 2035, 10 GW by 2045

According to Samsung C&T, the Swedish government is pursuing a roadmap to secure 2.5 GW of new nuclear capacity, SMRs and large reactors combined, by 2035 and 10.0 GW by 2045. The Studsvik-led project of four BWRX-300 units, 1.2 GW in total, targets commercial operation in the mid-2030s. The site is on land Studsvik owns that already holds a license to operate nuclear facilities.

🧱Who builds what#

The nuclear island and the rest of the plant

No single company builds an SMR project on its own. Kairos Power leads the technology, engineering, manufacturing, procurement and construction of the nuclear island, the core of the reactor, while Samsung C&T supports selected engineering and construction. In Sweden, Studsvik leads the project and handles licensing and government consultation, and Samsung C&T and GVH take part as co-EPC partners.

Kairos's integrated EPC team#

Starting with power generation and balance of plant

According to the Kairos Power release, Samsung C&T joins the Kairos-led integrated EPC team alongside other partners, initially focused on power-generation systems and balance-of-plant scope. Kairos's project management organization leads throughout development and construction and manages cost and schedule objectives. The agreement builds on a trilateral memorandum of understanding signed by Samsung C&T, Kairos and Barnard Construction on August 18.

Co-EPC in Sweden#

Chosen after a three-group competition

Samsung C&T and GVH were selected as strategic partners for Studsvik's project in Sweden after a competition among three groups that began in May last year, and announced the joint development agreement on September 3. Studsvik handles project development, including licensing, environmental impact assessment and government consultation. The two companies work together as co-EPC partners from the early stage through execution.

💰Construction starts after the money closes#

Financial close and investment conditions

In Romania, financial close has to come before construction. According to Samsung C&T's conference call, the Romanian SMR is scheduled to start construction after the EPC contract and financial close are completed within 2028, and that timing may change with feasibility reviews and progress toward financial close. Money going into developers carries conditions too: Samsung C&T's investment in Kairos Power is subject to regulatory approvals.

Romania's sequence#

Design, approval, licensing

Samsung C&T and NuScale completed front-end engineering design (FEED) for the Romanian SMR in November 2025, and Romania's nuclear power company approved execution of the project at a shareholders' meeting in February 2026. Pre-EPC work such as environmental impact assessment and licensing is now under way. Samsung C&T said it continues to monitor progress together with NuScale and Fluor.

Up to $100 million or about $70 million#

The investment in the two releases

Kairos Power said on September 21 that Samsung C&T will provide up to $100 million through direct investment and in-kind engineering services, and that the money is to help complete Hermes 2. The next day Samsung C&T announced it would pursue an investment of about $70 million. Samsung C&T's material does not break out an in-kind portion and adds that it has secured priority rights to perform EPC for commercial reactors.