ZettaJoule

What ZettaJoule does

ZettaJoule, Inc. is a U.S. private company founded in August 2023 that develops high-temperature gas-cooled reactor (HTGR) small modular reactors based on Japan's operational High Temperature Engineering Test Reactor (HTTR). Its core product, the ZJ reactor, is a 30 MWth TRISO-fueled, graphite-moderated, helium-cooled unit designed to operate at temperatures up to 950°C, approximately 600°C higher than conventional light-water reactors and above the operating envelope of China's HTR-PM (750°C). The ZJ uses a Hastelloy XR intermediate heat exchanger (the only nuclear structural material qualified for 950°C service) and integrates AI-based digital twins for operations, predictive maintenance, and construction logistics. The company is developing the ZJ0, a 30 MWth research reactor planned for Texas A&M's College Station campus under a February 2026 MOU with TEES, targeting construction completion in 2031–2033, and pursues a fleet of scalable, modular reactors up to 600 MWth.

ZettaJoule sells energy through an Energy-as-a-Service model under which it retains ownership, operation, and staffing of each reactor while customers act as long-term energy off-takers, eliminating the need for customers to manage nuclear assets. It targets hard-to-abate industrial sectors requiring process heat between 300°C and 950°C—oil and gas, chemicals, steelmaking, mining and refining, transportation and shipping fuels (SAF, e-fuels, hydrogen), and data centers—with secondary applications in district heating and desalination. Headquartered in Rockville, Maryland with a planned relocation to Houston, Texas, the company also operates through a Japanese subsidiary (ZettaJoule KK) with offices in Tokyo and Mito, and a wholly-owned workforce subsidiary (ZROC) for nuclear training and certification.

Revenue is generated (when it begins) via long-term, multi-year subscription-style offtake contracts for heat, electricity, and cooling. ZettaJoule is backed by venture investors including Globis Capital Partners, Coral Capital, Archetype Ventures, SOSV/HAX, and a corporate strategic backer in Aramco Services. Its leadership draws on former JAEA/HTTR program leaders (Chief Nuclear Officer Kazuhiko Kunitomi, Ph.D.), former NRC Director Andrea Veil, former CNSC President Rumina Velshi, former Mitsubishi Heavy Industries Executive Officer Yasushi Fukuizumi, and former X-energy/Westinghouse commercial executives, supporting a strategy that pairs a 10 CFR Part 50 research-reactor regulatory pathway with later commercial licensing.

Name

ZettaJoule

Legal name

ZettaJoule, Inc.

Website

https://zetta-joule.com

Company type

Private

Founded year

2023

Operating status

Operating

Headcount range

11–50 employees

Short description

ZettaJoule develops a 30 MWth high-temperature gas-cooled small modular reactor (up to 950°C) based on Japan's HTTR, selling zero-carbon heat, power, and hydrogen to industrial customers through an Energy-as-a-Service off-take model.

Ownership category

akta.pro rank

Product category

Advanced Small Modular Nuclear Reactors (HTGR)

NAICS

Nuclear Electric Power Generation (221113), Steam and Air-Conditioning Supply (221330)

SIC

Cogeneration Services & Small Power Producers (4991), Industrial Process Furnaces & Ovens (3567), Engines & Turbines (3510)

akta.pro primary industry

Gen IV / Advanced Reactor Systems (SFR, LFR, GFR, MSR, HTGR, Microreactors) (EUAKADAC)

akta.pro secondary industries

Gas-Cooled Reactor (AGR/HTGR) Power Generation (EUACADAD), Reactor Monitoring, Diagnostics & Predictive Maintenance (Sensors, Digital Twin, PHM) (EUAKADAM)

Keywords

• Advanced nuclear reactors
• Small modular reactors
• High-temperature gas-cooled reactors
• Process heat generation
• Clean energy services

Headquarters

HQ city

Rockville

HQ country

United States

HQ region

North America

Offices6 records

Markets served

GTM type

B2B

Offering type

Services

Cost components

Technology or R&D, Personnel, Infrastructure, Operations, Marketing or Sales, Supply Chain

Revenue model

1. Energy-as-a-Service (Offtaker Model): ZettaJoule owns reactor assets, sites them at customer premises, and sells thermal energy, electricity, and cooling under long-term offtake agreements. Customers can operate solely as off-takers without the complexities of owning or managing a nuclear facility. The company assumes ownership, operations, and staffing of reactor facilities.

Pricing tiers

Go-to-market motion1 record

Distribution channels2 records

Marketing channels7 records

Core offering

ZettaJoule develops the ZJ Reactor, an advanced small modular high-temperature gas-cooled reactor (HTGR) operating at up to 950°C and producing 30 MWth of thermal energy, based on Japan's High Temperature Engineering Test Reactor (HTTR) technology. The company delivers this technology through an Energy-as-a-Service model in which it owns, operates, and staffs reactors sited at customer facilities, with industrial customers purchasing heat, electricity, and hydrogen as off-takers under long-term offtake agreements. The subsidiary ZROC (ZettaJoule Reactor Operating Company) provides workforce training, education, and certification for nuclear professionals.

Product overview

ZettaJoule offers the ZJ Reactor as its core advanced small modular reactor product - a high-temperature gas-cooled reactor (HTGR) capable of operating at up to 950°C and generating 30 MWth. The company delivers this technology primarily through an Energy-as-a-Service model where ZettaJoule retains ownership, operation, and staffing responsibilities, allowing customers to purchase energy as off-takers. The first reference reactor, the ZJ0, is being developed in partnership with Texas A&M's TEES. The subsidiary ZROC (ZettaJoule Reactor Operating Company) provides workforce training and recruitment services to support the nuclear industry talent pipeline.

Differentiator

Problem solved

Functional benefit

Brands

• ZROC: ZettaJoule Reactor Operating Company - a wholly owned subsidiary dedicated to workforce training, education, and certification for nuclear energy professionals, as well as reactor operations.

Products and services

• ZJ Reactor An advanced small modular high-temperature gas-cooled reactor (HTGR) that operates at temperatures up to 950°C and generates 30 MWth of thermal energy, scalable to 600 MWth through modular deployment. Uses TRISO fuel particles, graphite moderation, and helium cooling for inherent passive safety. Designed for industrial off-takers needing zero-carbon heat, electricity, and hydrogen.
• Energy-as-a-Service A comprehensive energy delivery solution under which ZettaJoule owns, operates, and staffs nuclear facilities on customer sites, allowing industrial customers to purchase energy (heat, electricity, cooling) as off-takers under long-term offtake agreements without managing a nuclear plant. Reactors are available as single or multiple modules deployed on-site.
• ZROC (ZettaJoule Reactor Operating Company) Workforce Services A wholly owned subsidiary providing recruiting, training, education, and certification of nuclear engineers, plant operators, technicians, and other personnel for careers in advanced SMR operations. Recruits at local, regional, and national levels to support the nuclear industry talent pipeline.
• ZJ0 Research Reactor The first ZJ reactor project: a 30 MWth high-temperature gas research reactor to be built adjacent to the TEES Nuclear Engineering & Science Center in College Station, Texas. Based on technology from Japan's High Temperature Engineering Test Reactor (HTTR), it is designed to demonstrate very-high-temperature process heat applications including synthetic fuels, hydrogen, steelmaking, chemicals, desalination, and data centers.

Quantifiable outcome

• Up to 950°C heat output - approximately 600°C higher than conventional water-cooled reactors
• +4 more outcomes

Named customers1 record

Segments8 records

Ideal customer profiles6 records

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

AI capability4 records

Feature6 records

Partnerships

Four partnerships are on record, tiered core and flagship.

• Texas Nuclear AlliancecoreGTM or Marketing Partner · 20 April 2026ZettaJoule joined the Texas Nuclear Alliance (TNA) in April 2026. TNA is the only industry association in Texas dedicated to advancement of nuclear technology, formed with mission to make Texas the Nuclear Capital of the World. TNA helped pass House Bill 14, a $350 million state investment in nuclear energy. ZettaJoule's membership supports its Texas-based operations and partnerships.
• Texas A&M Engineering Experiment Station (TEES)flagshipStrategic or Co-development Partner · 26 February 2026Texas A&M TEES signed MOU with ZettaJoule on Feb 26, 2026 to explore building the ZJ0 very-high-temperature gas research reactor at Texas A&M's College Station campus. ZettaJoule would build the reactor adjacent to TEES Nuclear Engineering & Science Center. The project could catalyze up to $1 billion in research collaborations, industrial partnerships, and federal funding over the next decade. TEES would own the reactor and hold the NRC license, while ZettaJoule leads design, engineering, procurement, and construction management.
• Aramco ServicescoreStrategic or Co-development Partner · 19 December 2025Aramco Services provided official support for ZettaJoule's ZJ high-temperature gas-cooled reactor project designed to produce process heat up to 950°C. The project aims to serve as a reference for future commercial deployment, utilizing proven technology from Japan's HTTR. Aramco's backing signals industry and investor confidence in ZettaJoule's advanced SMR technology for industrial applications.
• Japan Atomic Energy Agency (JAEA)coreTechnology or IntegrationZettaJoule's technology is based on decades of operation at JAEA's High Temperature Engineering Test Reactor (HTTR) in Oarai, Ibaraki Prefecture, Japan. The HTTR has operated since 1998 and demonstrated 950°C outlet temperature capability in 2004 and 50-day continuous operation in 2010. JAEA's publicly available data provides the foundation for ZettaJoule's modernized advanced SMR technology.

Scale indicators4 records

Recent moves7 records

Expansion highlights6 records

Emerging players

• Ultra Safe Nuclear Corporation (USNC): Develops the Micro Modular Reactor (MMR) using TRISO fuel, a closely related technology to ZettaJoule's HTGR. Targets similar distributed industrial customers (mining, remote sites) with a smaller microreactor form factor.

Direct peers

• X-energy: Direct HTGR competitor developing the Xe-100 high-temperature gas-cooled reactor for industrial process heat and electricity. X-energy is an ARDP awardee with Dow Chemical as anchor industrial customer and pursues an overlapping target market (industrial decarbonization) with very similar technology positioning.
• Kairos Power: Advanced reactor developer building the Fluoride-salt-cooled High-temperature Reactor (FHR). Kairos has the only currently NRC-licensed non-LWR test reactor (Hermes) in the US and competes for industrial customers seeking clean firm power and process heat.
• NuScale Power: Only SMR with full NRC design approval (prior VOYGR design), targeting data centers, industrial sites, and utilities. While LWR-based (lower temperature) rather than HTGR, NuScale directly competes for many of the same industrial and data-center customers ZettaJoule targets.
• TerraPower: Bill Gates-backed advanced reactor company developing the Natrium sodium-cooled fast reactor paired with molten salt energy storage. Targets industrial customers and grid-scale firm clean power with similar long-duration customer offtake models.
• Holtec International: Develops the SMR-160, a 160 MWe light-water small modular reactor, and is licensing the Holtec SMR-300 with significant NRC engagement. Competes for industrial and utility customers seeking firm clean power.
• BWX Technologies (BWXT): Develops the BANR (BWXT Advanced Nuclear Reactor) high-temperature gas-cooled microreactor based on similar TRISO fuel technology. Competes in advanced reactor space with established nuclear manufacturing credentials and DoD/DOE relationships.

Regional players

• China National Nuclear Corporation (HTR-PM): State-owned Chinese nuclear operator of the HTR-PM, the world's only currently operational commercial HTGR (at 750°C). Provides a real-world reference for HTGR technology but operates exclusively in China and represents a different commercial and regulatory environment.
• Rolls-Royce SMR: UK-based SMR developer with UK government backing pursuing 470 MWe LWR units. Geographic focus is primarily the UK and European markets but increasingly targeting international industrial customers in adjacent geographies.

Broad incumbents

• Westinghouse Electric Company: Incumbent nuclear OEM now commercializing the AP300 SMR. While LWR-based rather than HTGR, Westinghouse brings decades of nuclear licensing and supply-chain experience and competes for industrial customers with the legacy nuclear-industry relationships that ZettaJoule is also pursuing.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks6 records

Key highlights7 records

Customer concentration

• Xx.com/ZettaJouleInc
• LinkedInlinkedin.com/company/zettajoule

Revenue estimate

Valuation estimate

Number of profiles

Profiles14 records

Subsidiaries2 records

Funding overview

Funding rounds1 record

Investors2 records

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about ZettaJoule