TerraPower

TerraPower
Company type	Private
Industry	Nuclear reactor design and development
Founded	2006
Founder	Bill Gates
Headquarters	Bellevue, Washington, United States
Key people	Chris Levesque (CEO)
Products	Traveling wave reactor, Natrium reactor
Owner	Bill Gates (via Cascade Investment) and other investors

TerraPower is a U.S.-based company specializing in the design and development of nuclear reactors, with its headquarters located in Bellevue, Washington. Established in 2006 by Bill Gates, the firm concentrates on pioneering nuclear innovations, particularly focusing on traveling wave reactor (TWR) advancements.

Description

The TWR technology developed by TerraPower features a compact core of enriched nuclear fuel encircled by a larger volume of depleted uranium. Neutrons emitted from the core facilitate the breeding of new fissile materials like Plutonium-239, which sustains the fission process as fuel rods are methodically repositioned to preserve the reactor’s fuel composition over time.

TerraPower’s Natrium reactor utilizes liquid sodium as its cooling medium, which reduces expenses by operating the primary loop at ambient pressure. The heat generated is transferred to molten salt, allowing energy storage and steam production on demand, enabling steady electricity generation with flexible dispatch capabilities. This configuration simplifies plant design and decreases containment size relative to traditional reactors, improving both cost-effectiveness and operational adaptability.

History

In September 2015, TerraPower formed a collaboration with the state-owned China National Nuclear Corporation to develop a 600 MWe prototype reactor in Xiapu, Fujian province, China, with a timeline from 2018 through 2025. Plans were made for commercial-scale reactors around 1150 MWe to be operational by the late 2020s. However, this initiative was discontinued in January 2019 following technology transfer constraints imposed by the Trump administration.

In October 2020, TerraPower was awarded a matching grant from the United States Department of Energy estimated between $400 million and $4 billion over a period of 5 to 7 years to construct a demonstration reactor based on its Natrium design.

By June 2021, TerraPower and PacifiCorp, part of Berkshire Hathaway Energy owned by Warren Buffett, announced intentions to co-develop a Natrium reactor. Four cities in Wyoming—Gillette, Kemmerer, Glenrock, and Rock Springs—were evaluated as potential sites due to their dependence on retiring fossil-fuel power plants managed by PacifiCorp's Rocky Mountain Power division. In November 2021, Kemmerer was chosen as the preferred location.

In 2024, TerraPower confirmed Kemmerer as the site for a 345 MWe Natrium reactor incorporating a molten salt energy storage system capable of increasing output to 500 MWe. This setup is designed to complement renewable energy integration. The facility will comprise an "energy island" alongside a "nuclear island". Groundbreaking took place in June 2024, with construction of the nuclear island slated for 2026 and commercial operation expected by 2030.

The total project budget is estimated at $4 billion, with half financed by the DOE and $1 billion contributed by Bill Gates. This funding supports TerraPower’s mission to advance next-generation nuclear technologies featuring improved safety and efficiency.

In April 2025, TerraPower began the UK’s Generic Design Assessment process for its Natrium reactor, indicating intentions for international expansion of its advanced nuclear technology offerings.

Funding and management

TerraPower secures financial support from the US Department of Energy and Los Alamos National Laboratory. Prominent backers include Bill Gates via Cascade Investment, alongside venture capital firms such as Charles River Ventures and Khosla Ventures, which contributed $35 million in 2010.

The organization is headed by CEO Chris Levesque. In 2011, India's Reliance Industries purchased a minority equity stake, with Chairman Mukesh Ambani joining TerraPower’s board of directors. The company’s workforce comprises specialists from Lawrence Livermore National Laboratory, the Fast Flux Test Facility, Microsoft, as well as industry veterans from Siemens, Areva NP, and the ITER initiative.

In 2022, SK Group invested $250 million, in a round co-led by SK Inc and SK Innovation alongside Bill Gates. TerraPower benefits from DOE support through the Advanced Reactor Demonstration Program (ARDP), which provides shared funding aimed at developing and licensing an advanced reactor within seven years.

The company’s strategic goals emphasize:

Driving innovation in nuclear energy through advanced technologies and computational modeling.
Evaluating new influences on the nuclear fuel cycle, spanning extraction to waste management.
Attracting autonomous private sector capital.

Traveling wave reactor

TerraPower’s flagship innovation is the traveling wave reactor (TWR), engineered for exceptional fuel utilization without the need for uranium enrichment or fuel reprocessing. This reactor converts fertile non-fissile isotopes (U-238) into fissile material (Plutonium-239) directly within the core, facilitating a closed fuel cycle that lowers proliferation risks.

The reactor is designed to operate with fuel embedded during fabrication for 40 to 60 years and can function underground for up to a century. As a Generation IV reactor concept, it offers competitive benefits by reducing fuel expenses while enhancing safety and operational lifespan.

Environmental effects

Utilizing depleted uranium as its fuel source, this reactor design has the potential to diminish existing depleted uranium stockpiles. TerraPower highlights that the United States holds approximately 700,000 metric tons of depleted uranium, with 320 metric tons sufficient to supply electricity to 100 million households for one year. The TWR’s efficient fuel use and capacity to extract uranium from river or seawater imply enough fuel availability to power 10 billion people at current US consumption rates over timescales extending into millions of years.

Research and development

The TWR remains under active research and development, with its theoretical model validated through supercomputer simulations. On November 6, 2009, TerraPower executives along with Bill Gates visited Toshiba’s manufacturing facilities in Japan, leading to a signed non-disclosure agreement on December 1. Toshiba had previously developed the ultracompact 4S reactor, which operated for three decades without refueling and generated 10 megawatts. Certain technologies from the 4S are considered adaptable for TWR applications, aligning with TerraPower’s approach of leveraging proven innovations to advance nuclear technology.

Molten salt reactor

Starting in October 2015, TerraPower initiated development of a molten salt reactor design in partnership with Southern Company as an alternative technology pathway. By February 2022, both organizations agreed to construct a demonstration fast-spectrum salt reactor at the Idaho National Laboratory (INL).

In 2023, the United States Department of Energy revealed plans for a test reactor utilizing highly enriched uranium (HEU) fuel containing up to 90% enrichment, which contrasts with national objectives aimed at phasing out HEU usage in reactors.

Sodium Fast Reactor (Natrium)

The Natrium system combines a molten sodium-cooled reactor with a 1 GWh molten salt energy storage facility. Due to sodium’s extensive liquid temperature range of 785 Kelvin, it can absorb heat efficiently without requiring pressurization, which improves both safety and operational performance in comparison to water-based systems.

This design incorporates austenitic stainless steel materials that form protective oxide films when exposed to sodium, significantly reducing corrosion. To manage corrosion risks, the reactor undergoes ultrasonic inspections and routine maintenance protocols.

Fuel for Natrium consists of high-assay, low enriched uranium (HALEU) metal slugs encased in steel fuel rods. This configuration provides better thermal conductivity than conventional ceramic fuels, despite having a lower melting temperature.

The reactor boasts a compact footprint and achieves energy efficiency approximately four times greater than traditional nuclear plants. It consistently produces 345 MWe at full power output. For safe shutdowns, the control rods operate by gravity. The integrated energy storage system supports intermittent renewable sources by supplying up to 500 MWe (150% of the nominal capacity) for 5.5 hours, thereby improving grid reliability and operational flexibility.

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