3 Next-Gen Nuclear Reactor Projects Move Forward in 2025

The U.S. Nuclear Regulatory Commission (NRC) is reviewing several advanced reactor designs, setting small modular reactor (SMR) developers on a solid path toward bringing their first power plants online within the next decade.

Producing 300 MW per unit, SMRs are a new class of nuclear power reactors with about a third of the generating capacity of conventional plants. These next-generation light-water reactors are “always on,” providing 24/7 baseload energy to cover peak demand or emergency backup power. Their compact size and factory-assembled design save costs and offer flexibility in space-constrained sites like retired coal plants. SMRs’ modest physical footprint also makes them an attractive alternative to solar and wind farms.

Regulators are reviewing several promising SMR projects by Kairos Power, NuScale Power, and Westinghouse.

Westinghouse’s AP300 SMR. Image used courtesy of Westinghouse

Kairos Power’s Hermes 2 Test Reactor

In November 2024, the NRC issued construction permits for Kairos Power’s Hermes 2 demonstration plant in Oak Ridge, Tennessee. The California-based company has developed a high-temperature fluoride salt-cooled reactor fueled by TRISO particles embedded in a carbon matrix pebble. Hermes 2 builds on insights from its predecessor, a low-power demonstration unit. In 2023, Hermes 1 was the first Generation IV reactor to secure an NRC construction permit.

Architect rendering of Kairo Power’s Hermes 2 Demonstration Plant in Tennessee. Image used courtesy of Kairos Power

The new unit, projected to become operational in 2027, will demonstrate a scaled version of the plant architecture to supply energy to the grid. Before startup, the NRC must authorize an operating license for Kairos.

While the full-scale Hermes plant accommodates 320 MW of capacity, the thermal test reactor will only reach 35 MW. The design employs low-pressure molten salt to cool the cores. A steam cycle converts fission-produced heat into electricity. Pebble-type TRISO fuel serves as Hermes’s containment function. This fully ceramic fuel retains structural integrity at extreme temperatures exceeding the melting level of conventional metallic fuels.

Kairos signed an agreement with Google to supply up to 500 MW from its first reactor by 2030, serving sites near the tech giant’s data centers.

The process behind Kairos Power’s molten salt-cooled reactor. Image used courtesy of Kairos Power

NuScale Power SMR Design

The NRC certified NuScale Power’s reactor design in 2023—a national milestone for SMRs in the U.S. The agency is reviewing the company’s standard design application for a 464-MW plant with six power modules at 77 MW each. According to NuScale’s third-quarter earnings presentation last November, the NRC’s power uprate remains on track for mid-2025 approval.

NuScale’s VOYGR plant design draws upon the fundamentals of conventional pressurized water-cooled reactors. However, each 77-MW module can be scaled to meet customers’ site and power requirements. Three VOYGR variants offer flexible configurations—four, six, or 12 modules—with up to 924 MW of output.

NuScale’s VOYGR-6 reactor (top) produces 462 MW through six power modules, while the 12-module VOYGR-12 version (bottom) generates 925MW. Images used courtesy of NuScale Power

Operating with 1/20 of the fuel used in a large-scale reactor, VOYGR’s core design offers improved stability and minimizes fuel damage. The company boasts an efficient containment vacuum comprising high-strength steel to limit heat loss and oxygen content.

NuScale president and CEO John Hopkins stated that the company is seeing unprecedented interest in its technology for supporting the power demands of AI and advanced computing.

The NRC is reviewing the advanced safety evaluation, with standard design approval slated for July 2025.

Westinghouse AP300 SMR

Another project in the NRC’s pre-application pipeline is Westinghouse’s AP300 SMR, a 330 MW single-loop pressurized water reactor. The design is based on the company’s signature AP1000 light-water system, which has been deployed worldwide for decades, including at the newly built Plant Vogtle nuclear power facility in Georgia.

AP300 end-users will include industrial plants, utilities, district heating, and water production facilities. Image used courtesy of Westinghouse

AP300, like its predecessor, is designed to operate for over 80 years and will use the same fuel, supply chain, and key components as AP1000. It will also feature Westinghouse’s advanced passive safety systems that eliminate the need for backup power or operator action.

Westinghouse unveiled the SMR in 2023, anticipating design certification by 2027 and site-specific construction and licensing on the first unit by 2030. The company has completed the conceptual design phase, including critical milestones like validating design choices and documentation based on the AP1000 plant technology.