FAQs

What is fusion?

Fusion is the process where two atomic nuclei combine to make a single heavier one releasing a large amount of energy. Fusion technologies may be able to generate large amount of energy using less fuel than fission technologies. This reaction is typically achieved with hydrogen isotopes like deuterium and tritium. The most well-known example of this reaction is found in the Sun.

There are several approaches currently being explored for commercial use, including magnetic confinement (such as in tokamaks and stellarators), inertial confinement (using lasers or particle beams), and alternative concepts like magnetized target fusion. These methods aim to recreate extreme conditions similar to those found on the sun to sustain fusion and deliver practical energy output.

How is fusion different than fission?

Fission and fusion are both nuclear reactions that release energy, but they operate in fundamentally different ways. Fission occurs when an atomic nucleus, such as uranium or plutonium, splits into smaller nuclei, releasing energy, and additional neutrons that can sustain a chain reaction. This process is used in traditional nuclear power plants, which produce long-lived low-level radioactive waste and high-level waste (i.e., spent fuel).

Fusion, on the other hand, involves combining two atomic nuclei, typically hydrogen isotypes like deuterium and tritium, to form a heavier nucleus, usually helium, and neutrons. This reaction releases significantly more energy than fission and, when used for power production, is expected to produce minimal long-lived low-level waste radioactive waste. The neutrons produced in the fusion reaction may be captured to produce more tritium for fueling the fusion machine using a breeding bed or blanket that surrounds the fusion machine. Some of the neutrons are captured in the components that make up the fusion machine that can “activate” the non-radioactive atoms into radioactive atoms (i.e., can form unstable isotopes susceptible to radioactive decay). This production of radioactive materials known as activation products requires safe handling during maintenance operations and activated components may need to be disposed of as low-level radioactive waste or be recycled. Tritium used and produced in a fusion machine can also be absorbed by other materials, contaminating some components of the fusion machine.

What is the fuel source for fusion?

The primary fuel for fusion technologies currently under development is hydrogen isotopes, specifically deuterium and tritium. Deuterium is abundant in seawater, while tritium is rare. Most commercially available tritium today is produced in certain kinds of fission reactors, and some commercial fusion technologies are expected to rely on creating or “breeding” tritium  using lithium, which can produce tritium after absorbing neutrons. Researchers are exploring other fusion reactions, such as those using deuterium-helium-3 or proton-boron, for future applications. All fuels currently under consideration are highly efficient, and fusion machines using them would produce minimal long-lived radioactive waste, making fusion a promising energy solution.

Why do they have to breed tritium in a commercial fusion device?

Commercial fusion devices must breed tritium because there is not enough naturally occurring or commercially available tritium to sustain large-scale fusion power generation. Tritium is a radioactive isotope of hydrogen with a half-life of about 12.3 years, meaning it decays relatively quickly and cannot be stockpiled over long periods. Existing global tritium supplies—produced primarily as a byproduct in a small number of fission reactors—are extremely limited and insufficient to support the fuel demands of commercial fusion. A deuterium-tritium (D-T) fusion reactor is expected to consume hundreds of kilograms of tritium per year, far exceeding current production capacity. To overcome this challenge, fusion devices are designed with a lithium breeding blanket that captures high-energy neutrons from the fusion reaction to produce new tritium, enabling a self-sustaining fuel cycle essential for the viability of fusion energy. Researchers currently expect many fusion machines to be designed with a layer of lithium surrounding the fusion chamber like a blanket. This lithium breeder blanket would capture the high-energy neutrons, preventing their release and producing new tritium.

What is a fusion machine?

The ADVANCE Act added the term “fusion machine” to the Atomic Energy Act of 1954, as amended. Fusion machine is defined as “a machine that is capable of (1) transforming atomic nuclei, through fusion processes, into different elements, isotopes, or other particles; and (2) directly capturing and using the resultant products, including particles, heat, or other electromagnetic radiation.”

The NRC staff incorporated this definition into the proposed fusion regulations. The fusion machine definition is technology neutral and recognizes that there are many different ways to perform fusion. The definition also requires that the fusion machine directly capture and use the resultant products of the fusion process.

What is an Agreement State?

An Agreement State is a U.S. state that has entered into a formal agreement with the NRC to regulate the use of certain radioactive materials within its jurisdiction. Under this agreement, the state takes over responsibility for licensing, inspecting, and enforcing safety regulations for byproduct, source, and small quantities of special nuclear material. To become and remain an Agreement State, the state's regulatory program must be reviewed and approved by the NRC and must be at least as protective of public health and safety as the NRC’s own regulatory program. The NRC continues to regulate other activities, such as fission reactors and larger fuel facilities, even in Agreement States.

What is the National Materials Program

The National Materials Program (NMP) refers to the broad, collective framework within which both the NRC and the Agreement States function in carrying out their respective regulatory programs for radioactive material. The mission of the NMP is to create a partnership between the NRC and Agreement States that will ensure protection of public health, safety, security, and the environment from the hazards associated with radioactive material.

The vision of the NMP is to provide a coherent national system for the regulation of agreement material with the goal of protecting public health, safety, security and the environment through compatible regulatory programs. Through the NMP, the NRC and Agreement States function as regulatory partners.

How are the NRC and Agreement states working together

Under the Agreement State program, the NRC and Agreement States function as regulatory partners and work together on development of regulatory guides and procedures, development of regulation, and the Integrated Material Performance Evaluation Program (IMPEP).

Through this relationship, the NRC works with all Agreement States to develop a comprehensive framework for the regulation of fusion machines, including the ongoing fusion rulemaking. Commercial fusion development is currently occurring in and regulated by the Agreement States, which is expected to continue. The NRC and Agreement States have been working closely on the development of the fusion framework through the collection of comments and discussion through outlets such as government-to-government meetings.

Why is the NRC conducting rulemaking for fusion machines?

The NRC is conducting rulemaking to establish a clear and appropriate regulatory framework for the development and deployment of fusion machines. Unlike nuclear fission, fusion does not involve chain reactions and is not expected to produce long-lived radioactive waste. By developing specific rules, the NRC aims to provide regulatory certainty for fusion developers while ensuring public safety and environmental protection. This effort supports the responsible advancement of fusion energy as it moves closer to commercialization.

Additionally, the NRC’s direction on fusion regulation is guided by federal legislation, including the Nuclear Energy Innovation and Modernization Act (NEIMA) and the Accelerating Deployment of Versatile, Advanced Nuclear for Clean Energy (ADVANCE) Act. NEIMA mandates the NRC to modernize its regulatory framework for advanced nuclear technologies, including fusion. The ADVANCE Act amended the Atomic Energy Act (AEA) to clarify that fusion machine produced radioactive material meets the definition of byproduct material and further supports streamlined regulatory processes for emerging nuclear technologies. These legislative efforts reinforce the NRC’s commitment to developing a regulatory structure that enables fusion energy while maintaining rigorous safety and security standards.

How is the NRC interacting and informing the public?

The NRC recognizes the public’s interest in the rulemaking and fusion activities. The NRC has hosted several public meetings throughout the rulemaking process to update the public and industry as well as receive comments and question. Additional public meetings and outreach will be conducted as the activities progress.

What is the ADVANCE act and how does it affect fusion?

The ADVANCE Act was signed into law in July 2024. The Act focuses on a broad range of activities at the NRC, including supporting retention, flexibility of budgeting process, and enhancing the framework for advanced reactors. Section 205 of the ADVANCE Act is specific to fusion and amended the NRC’s primary statute, the Atomic Energy Act of 1954, as amended, by adding a new definition of “fusion machine” and incorporated fusion machine produced radioactive material into the definition of “byproduct material.”

Section 205 of the ADVANCE Act also tasked the NRC with a report related to mass-manufactured fusion machines, which is due to Congress in July 2025.

How are fusion machines regulated?

Fusion machine produced radioactive material is regulated under the byproduct material framework in Title 10 of the Code of Federal Regulations (10 CFR), Part 30, “Rules of General Applicability to Domestic Licensing of Byproduct Material.”

Are particle accelerators similar to fusion machines and are they being regulated the same way?

The Atomic Energy Act (AEA) includes fusion machines as subset of particle accelerators in the definition of byproduct material. Fusion machines and other particle accelerators produce radioactive material and share similar characteristics. However, the AEA defines all fusion machine produced radioactive material as byproduct material, but radioactive material produced by other particle accelerators is only considered byproduct material if produced “for use for a commercial, medical, or research activity.”

Currently, particle accelerators regulated by the NRC are typically used to commercially produce radioactive material for medical purposes. These machines are generally very similar in design and operation. In contrast, there are a wide range of fusion machine designs currently being developed. Most fusion machine designs currently in development are aimed at producing electricity, but developers are also working on other designs for producing heat, isotopes, and propulsion. Regulations specific to fusion machines would provide regulatory clarity for this wider scope of approaches and applications. A distinct regulatory framework would align with the potential hazards of the byproduct material associated with the technology.

Are companies or research organizations generating fusion energy now?

Currently there are no fusion machines that are commercially operational in the United States producing electricity, but there are over 20 companies working toward this goal.

What is the role of the U.S. Department of Energy compared to the NRC as related to fusion?

The Department of Energy (DOE) and the NRC play distinct but complementary roles in the development of fusion energy.

The DOE is primarily responsible for advancing fusion energy through research, innovation, and technology development. It funds and conducts scientific work at national laboratories, universities, and through public-private partnerships. The DOE plays a central role in fostering innovation by supporting new fusion concepts, materials research, and advanced modeling techniques, all aimed at overcoming the technical challenges of making fusion a practical energy source. It also oversees major fusion research facilities under the Office of Science.

In contrast, the NRC, in cooperation with Agreement States, is responsible for regulating the safety and security of commercial fusion facilities as they move toward deployment. The NRC and Agreement States ensure that fusion systems operate in a manner that protects public health and the environment through licensing, oversight, and enforcement.

In short, the DOE drives fusion innovation and development, while the NRC ensures its safe and responsible commercialization.

What does the report to Congress (due July 2025) entail?

Section 205 of the ADVANCE Act tasked the NRC with performing a study to develop recommendations for guidance or a regulatory framework to support licensing of mass-manufactured fusion machines and to establish an estimated timeframe for issuance. The NRC will provide the results of the study in a report to Congress by July 2025.

What is the timeline for the commercialization of fusion energy?

The fusion industry predicts that fusion power will be available and on the grid by the 2030s. The NRC’s focus is in making sure that the operation of these machines is done safely with the fusion regulatory framework that is required through the Nuclear Energy Innovation and Modernization Act.

What is the status of the current rulemaking process

The proposed rule package (SECY-24-0085, “Options for a Regulatory Framework for Fusion Energy Systems”) was submitted to the Commission on December 11, 2024, and is currently under Commission Review.

When will the fusion rulemaking package be available to the public?

The Proposed rulemaking package (SECY-24-0085) is available to the public. The finalized rulemaking package will be available to the public once it has gone through Commission approval.

What direction was given to the NRC staff by the Commission?

On April 13, 2023, the Commission approved a limited rulemaking and directed NRC staff to incorporate the regulation of fusion machines into the NRC’s existing regulatory framework for byproduct material through issued SRM-SECY-23-0001, "Staff Requirements – SECY-23-0001 – Options for Licensing and Regulating Fusion Energy Systems." On December 11, 2024, staff submitted a proposed rule to the Commission.

What is the role of Tritium in fusion?

Tritium is a key fuel in fusion reactions, particularly in deuterium-tritium (D-T) fusion, which is the most efficient reaction for producing energy. Fusing tritium with deuterium releases a large amount of energy and a high-energy neutron, which scientists can use to sustain the reaction and generate electricity. However, tritium is radioactive and scarce. Meeting the demands of a commercial fusion industry may require "breeding" tritium within the fusion machine to ensure a sustainable fuel supply. Breeding refers to the process of generating tritium from lithium. High-energy neutrons from the fusion reaction interact with lithium-containing materials in the reactor’s blanket, producing new tritium that operators would extract and reuse as fuel.

Is anyone generating fusion energy now?

Research facilities worldwide are conducting experimental fusion reactions, but no fusion energy is currently being generated for commercial use. Laboratories such as the International Thermonuclear Experimental Reactor (ITER), the National Ignition Facility (NIF), and private ventures have successfully achieved fusion reactions, with some experiments demonstrating net energy gain. ITER, an international collaboration in France, is the world’s largest fusion experiment, designed to demonstrate the feasibility of sustained fusion energy using magnetic confinement. However, sustaining fusion long enough to produce continuous, practical energy remains a challenge, and researchers continue working toward machines capable of delivering reliable fusion power in the future.