Regulating the Power of the Sun: Fusion Energy Breakeven Is a Breakthrough


March 14, 2023

Fusion energy is hot. And not just literally. The scientific community is abuzz about a recent announcement that Lawrence Livermore National Laboratory scientists achieved the first energy breakeven from a fusion reaction. This scientific breakthrough—the first time that a fusion reaction produced more energy than was used to start the reaction—means that we are one step closer to being able to harness the power of the stars to generate carbon-free electricity with far less radioactive waste than nuclear fission.

The US Nuclear Regulatory Commission (NRC) has been monitoring fusion energy developments for several years. In 2019, Congress directed the NRC to develop a regulatory framework for advanced reactors, including fusion reactors. Over the last two years, the NRC staff has been working to assess the risks from different fusion technologies and the possible approaches to regulating them. Based on input from stakeholders and reviews of fusion technologies, in January 2023 the NRC staff submitted to the Commission three proposals for regulating fusion energy systems.

Already, Commissioner Annie Caputo has expressed her views and approved a modified version of one of the three regulatory options. Under Commissioner Caputo’s approach, the NRC would conduct a “limited-scope rulemaking” to regulate fusion energy systems under the NRC’s byproduct material regulatory framework. Until the other four commissioners vote, however, the regulatory path for fusion energy systems remains uncertain. What is certain is that work on developing fusion energy systems will continue.

Fusion Energy Overview

Every nuclear power plant in operation today harnesses the power of nuclear fission—the splitting of heavy atoms such as uranium-235. When a uranium-235 atom is struck by a neutron, it splits into smaller atoms and releases additional neutrons to fuel a nuclear chain reaction. Nuclear fission releases large amounts of energy. But nuclear fission also generates radioactive fission products (the elements produced when uranium splits) along with small amounts of elements heavier than uranium (e.g., plutonium), which are also radioactive.

Nuclear fusion, on the other hand, involves fusing light elements such as hydrogen together to make a heavier element such as helium. This is the process that powers the stars, including the sun. The fusion reaction also releases tremendous amounts of energy. But unlike fission, the fusion reaction produces far fewer radioactive byproducts.

Unfortunately, it also takes vast amounts of energy to get hydrogen atoms to fuse, so attempts at fusion have required more energy to start the reaction than the reaction would produce. This is why the recent announcement on energy breakeven was heralded as a breakthrough in the work to make fusion power a useable energy source.

To produce fusion energy, hydrogen—typically in the form of deuterium or tritium—is heated into a plasma. The plasma, which is so hot that the electrons are stripped from the atoms forming an ionized gas, must be confined to allow the nuclei to fuse. Three confinement strategies are being pursued for commercial fusion energy systems: (1) magnetic confinement, (2) inertial confinement, and (3) magneto-inertial confinement. When the nuclei fuse, they produce high-energy particles that are used in other nuclear reactions within the system to heat and maintain the plasma or to breed tritium from lithium. These particles can also be used to produce heat to generate electricity.

NRC’s First Steps Toward Regulating Fusion Energy

The NRC has been monitoring the developments in fusion energy systems for several years. In 2009, the Commission asserted “as a general matter, that the NRC has regulatory jurisdiction over commercial fusion energy devices whenever such devices are of significance to the common defense and security, or could affect the health and safety of the public.” The Commission directed the NRC staff to monitor developments in fusion technologies but, because of the uncertainties surrounding fusion technologies, it directed the staff not to expend “significant resources” on developing a regulatory framework for fusion until commercial deployment was “more predictable.”

In 2019, Congress passed the Nuclear Energy Innovation and Modernization Act (NEIMA) to provide a program to develop the US technical expertise and regulatory processes for the commercialization of advanced nuclear reactors. NEIMA’s definition of advanced reactors includes both advanced fission reactors and fusion reactors. NEIMA directed the NRC to establish regulations for advanced reactors no later than by the end of 2027.

The NRC staff is now developing 10 CFR Part 53 for advanced fission reactors. But the Commission recognized that fusion reactors have fundamental differences from fission reactors that may require a different regulatory regime. The Commission thus directed the NRC staff to “consider the appropriate treatment of fusion reactor designs” under the NRC’s regulatory structure and to develop and present options for licensing and regulating fusion energy systems.

To do so, the NRC staff held six stakeholder meetings to discuss emerging fusion technologies and potential regulatory structures. Following this outreach and information gathering, the NRC staff focused on the most likely near-term concepts under development for potential deployment in the United States. The NRC staff found that these concepts shared several features:

  • They would not use fissile material, and criticality (a self-sustaining neutron chain reaction) is not possible.
  • Energy and radioactive material production from fusion reactions stops without any intervention in “off-normal events or accident scenarios.”
  • Active post-shutdown cooling of the fusion device’s structures is not necessary to prevent a loss of confinement (i.e., a containment vessel breach).
  • The radionuclides present in fusion devices and in activated materials are expected to result in a low dose to workers and members of the public during credible accident scenarios.
  • Contemplated designs require active engineered features (e.g., plasma confinement mechanisms) to achieve a self-sustaining fusion reaction.

With these concepts in mind, the NRC staff looked at how fusion energy systems could fit within the NRC’s existing regulatory structures. First, the NRC staff looked at whether fusion energy systems could be classified as “utilization facilities,” a category that includes existing nuclear fission power reactors. Second, the staff examined whether fusion energy systems could be classified as particle accelerators and regulated under the NRC’s byproduct material license framework. The NRC staff then developed three “regulatory framework options” for fusion energy for the Commission to consider.

Three Options for Regulating Nuclear Fusion

Option 1: Regulate Under a Utilization Facility Framework

Under this option, fusion energy systems would be licensed and regulated as utilization facilities (a category that includes existing fission plants). But to pursue this option, the Commission would need to define fusion energy systems as utilization facilities under its regulations through a rulemaking and develop a whole new set of technology-neutral regulations. The advantage of this approach would be that the NRC staff could apply a single regulatory framework to both fission and fusion reactors.

The disadvantage of categorizing fusion energy systems as utilization facilities is that it would subject them to several requirements currently applicable only to fission reactors, including Price-Anderson Act financial protection, foreign ownership and control restrictions, mandatory hearings, and operator licensing. These requirements would apply even if the risk of a release of radioactivity from the fusion energy system were small. This approach would also mean that states would have no role in the licensing and regulation of fusion energy systems, and significant NRC staff resources would be needed to develop a new regulatory structure.

Option 2: Regulate Under a Byproduct Material Framework

Under this option, fusion energy systems would be licensed under radioactive materials regulations, specifically the byproduct material regulations in Part 30. The main advantage of this approach is that it would require only a limited-scope rulemaking, which would be faster than developing a new regulatory structure. This would allow developers to proceed with a measure of regulatory certainty. It would also allow for NRC Agreement States to have a role in licensing these facilities.

According to the NRC staff, the disadvantages of this option are that some devices using certain technologies may fall outside the Atomic Energy Act’s byproduct material provisions, and larger fusion energy systems that present higher potential safety hazards may require specific license conditions to be appropriately regulated, creating regulatory uncertainty for some developers. The Fusion Industry Association’s position, however, is that this option could be used regardless of a fusion energy system’s size or technological approach.

Option 3: Regulate Under a Hybrid Framework

Under this option, the NRC staff would develop through rulemaking a framework for determining whether a fusion energy system should be regulated as a utilization facility or under a byproduct material approach. When an application is received, the characteristics of the system would be analyzed to determine which regulatory approach should apply.

The advantages of this approach are that it would encompass all fusion energy systems and would be a scalable regulatory approach. The regulations and associated guidance would provide developers with a measure of regulatory clarity. This approach would also provide Agreement States with input on licensing.

The disadvantages of this option are that it would involve a significant commitment of staff resources to develop the decision criteria and, until a framework is established, would create regulatory uncertainty for developers.

Awaiting Commission Action

The Commission must now decide whether to approve or disapprove these options. So far, only Commissioner Caputo has voted. Commissioner Caputo agreed with the Advisory Committee on Reactor Safeguards, which concluded that using the NRC byproduct material regulations in 10 CFR Part 30 “is appropriate for near term applications and will provide regulatory certainty while allowing for innovation and maturation” of fusion energy concepts. Commissioner Caputo strongly disapproved the NRC staff’s proposed hybrid approach (Option 3) and approved, with some modification, Option 2.

Commissioner Caputo would have the NRC staff conduct a limited-scope rulemaking to provide consistency across the National Materials Program that would regulate fusion under the byproduct material regulations. This would include defining “fusion” and “fusion energy system” in those regulations and updating the definition of “particle accelerator” to include material associated with the operation of a commercial fusion energy system. Under Commissioner Caputo’s approach, the NRC staff would also determine the appropriate security requirements for large quantities of tritium that could be stored at commercial fusion plants.

No action will be taken until the rest of the Commission votes.