What Is Nuclear Engineering? Research Areas, Regulation, Funding, and Careers

Nuclear engineering is the branch of engineering that applies the physics of the atomic nucleus to practical systems: nuclear power reactors, radiation-based medical and industrial technologies, radioactive-materials management, space and naval propulsion, and nuclear security. Where nuclear physics asks how nuclei are structured and how they interact, nuclear engineering asks how to harness those interactions safely, reliably and economically, and how to control the radiation and radioactive materials that result. It is a small but unusually heavily regulated field: almost every research reactor, radiation source, fuel sample and piece of technical data a nuclear engineer works with falls under a licensing regime, a federal safety rule, or an export-control category. That regulatory layer is as much a part of doing nuclear engineering research as the physics itself, which is why this guide covers it alongside the science.

What nuclear engineering actually studies

At its core the discipline is organized around a handful of recurring problems. How do neutrons move through, slow down in, and get absorbed by a material, and how does that determine whether a chain reaction can be sustained? How is the energy released by fission (or, in fusion research, by fusing light nuclei) removed and converted into something useful? How do fuels and structural materials behave after years of intense radiation, heat and corrosion? How are people and the environment protected from radiation, and how are spent fuel and other radioactive waste handled for very long periods? Answering these questions draws on several foundations taught in essentially every nuclear engineering program:

• Nuclear and atomic physics — nuclear structure, radioactive decay, and how radiation interacts with matter, building on the fundamentals covered in CASRAI’s guide on what physics is.
• Neutron transport and reactor physics — the behavior of the neutron population in a reactor core: criticality, reactivity, flux distributions and fuel depletion over time.
• Thermal hydraulics — heat generation, heat transfer and coolant flow, which draw directly on the thermodynamics and fluid-mechanics core of mechanical engineering.
• Nuclear materials — how fuels, cladding and structural alloys swell, embrittle, crack and corrode under irradiation.
• Radiation detection, shielding and protection — measuring radiation, attenuating it, and limiting human exposure.

Methodologically, nuclear engineering is unusual because many of its most important experiments are difficult, slow or impossible to run freely. Irradiating a material to reactor-relevant damage levels can take months or years and requires access to a test reactor or accelerator; handling irradiated samples requires shielded facilities. As a result the field leans heavily on validated computational modeling, on small-scale and separate-effects experiments, and on shared national facilities.

Major subfields of nuclear engineering

Most nuclear engineers specialize. The principal subfields are:

• Reactor engineering and design — the analysis and design of fission reactors, from the large light-water reactors that supply most nuclear electricity today to advanced concepts such as high-temperature gas-cooled, molten-salt, sodium-cooled and small modular reactors.
• Nuclear fuel cycle — mining and enrichment, fuel fabrication, in-core fuel management, reprocessing and recycling options, and spent-fuel storage and disposal.
• Nuclear safety and risk assessment — accident analysis, probabilistic risk assessment, severe-accident behavior and the design of defense-in-depth.
• Nuclear materials and radiation effects — the study of materials under irradiation, essential for extending the life of existing plants and qualifying new fuels and alloys.
• Fusion engineering and plasma science — the engineering of plasma-facing components, magnets, tritium handling and blankets for fusion devices. It overlaps with plasma physics and with the broader particle and nuclear physics research community.
• Radiation detection, instrumentation and health physics — detectors, dosimetry and the protection of workers and the public. CASRAI’s guides on the radiation safety officer role, ALARA, time, distance and shielding and how dosimetry badges work cover the day-to-day practice that health physicists oversee in university and hospital settings.
• Nuclear medicine and medical applications — production of medical radioisotopes, radiation therapy physics, and imaging technology, which links to biomedical engineering.
• Nuclear nonproliferation, safeguards and security — technical methods for accounting for nuclear material, detecting illicit trafficking, and verifying treaty compliance.
• Nuclear waste management and environmental remediation — characterization, treatment, storage and disposal of radioactive waste, including the legacy cleanup of former weapons-production sites. For the laboratory scale of this problem, see CASRAI’s guide on radioactive waste disposal and decay-in-storage.

How nuclear engineering relates to neighboring disciplines

Nuclear engineering is deliberately interdisciplinary and borrows from nearly every other branch of engineering. Thermal hydraulics and structural analysis come from mechanical engineering; instrumentation, control and power systems from electrical engineering; fuel-cycle and separations chemistry from chemical engineering; and siting, shielding structures and decommissioning have a civil-engineering dimension. The environmental side of the field, including waste isolation and remediation, connects to environmental engineering. The boundary with nuclear physics is mainly one of purpose: a nuclear physicist measures a cross section to learn about nuclear structure, while a nuclear engineer needs the same cross section as an input to a reactor model and cares about its uncertainty in that context. The two fields share data libraries, detectors and facilities, and their researchers frequently publish in the same venues.

Research methods, tools, and facilities

Nuclear engineering research combines simulation, experiment and data. Commonly used approaches include:

• Monte Carlo radiation transport. Codes such as MCNP (developed at Los Alamos National Laboratory), OpenMC (an open-source code) and Geant4 follow individual particles through geometry to predict reaction rates, doses and shielding performance.
• Deterministic neutronics and lattice codes used for routine core design and fuel-management calculations, with evaluated nuclear data libraries (such as ENDF) supplying the underlying cross sections.
• Thermal-hydraulic system codes and computational fluid dynamics for coolant behavior and transients.
• Multiphysics fuel and materials modeling, coupling heat transfer, mechanics and irradiation effects; the MOOSE framework developed at Idaho National Laboratory is a widely used example.
• Experiments at research reactors and accelerators, including neutron activation analysis, irradiation-damage studies, and ion-beam irradiation used as a faster surrogate for neutron damage.
• Post-irradiation examination of fuel and materials in shielded hot cells, using microscopy, mechanical testing and spectroscopy.
• Radiation detection and spectroscopy, from gamma-ray spectrometers to neutron detectors, for characterization and safeguards work.
• Uncertainty quantification, verification and validation, a major methodological concern because safety-relevant conclusions must be traceable to benchmarked codes and data.

Because irradiation facilities are scarce, much university research depends on access to shared infrastructure. Several US universities operate NRC-licensed research and test reactors, and the Department of Energy’s national laboratories host user facilities that university groups can propose experiments at. Facility access, sample shipment and instrument time are therefore routine considerations when planning a nuclear engineering project, and they are a significant source of the administrative workload described below.

A short history

The field grew out of the Manhattan Project. On December 2, 1942, a team led by Enrico Fermi at the University of Chicago achieved the first controlled, self-sustaining nuclear chain reaction in Chicago Pile-1. After the war the US Atomic Energy Act of 1946 placed nuclear development under civilian control through the Atomic Energy Commission, and the Atomic Energy Act of 1954 opened the way to private-sector and commercial uses of nuclear energy under federal licensing. In December 1951 the Experimental Breeder Reactor I in Idaho produced the first usable electricity from nuclear fission, and the Shippingport Atomic Power Station in Pennsylvania, which began operating in 1957, was an early full-scale civilian power reactor. Nuclear engineering emerged as a distinct academic discipline in this period, as universities began offering dedicated programs to train the workforce for reactor development. The professional society for the field, the American Nuclear Society, was founded in 1954.

Regulation then evolved in response to events. The Energy Reorganization Act of 1974 split the Atomic Energy Commission’s promotional and regulatory roles: the Nuclear Regulatory Commission was created to regulate civilian nuclear activities, and what became the Department of Energy took over the research and development functions. The 1979 Three Mile Island accident in Pennsylvania, the 1986 Chernobyl accident in Ukraine and the 2011 Fukushima Daiichi accident in Japan each reshaped safety research priorities and regulatory requirements, and each is a standard case study in nuclear safety courses. In recent years policy attention has returned to advanced reactor licensing, and the ADVANCE Act of 2024 was enacted to support the deployment of new nuclear technologies and the NRC’s work on them.

Regulation and oversight that shape research

Nuclear engineering researchers work inside several overlapping regulatory systems. They differ by who regulates, what they cover, and how directly they touch an academic lab.

The Nuclear Regulatory Commission (NRC)

The NRC licenses and regulates civilian use of nuclear materials and facilities in the United States. Commercial power reactors and research and test reactors are licensed under Title 10 of the Code of Federal Regulations, principally Part 50 (and Part 52 for combined licenses and design certifications). University research reactors are licensed this way, as are the radioactive materials used in many labs, which are typically held under a materials license or a broad-scope license administered through a radiation safety program. Radiation protection standards for licensees, including occupational dose limits and the ALARA principle (as low as reasonably achievable), are set in 10 CFR Part 20. The NRC also regulates exports and imports of certain nuclear equipment and material under 10 CFR Part 110. Some states, called Agreement States, have assumed NRC regulatory authority over certain materials, so a campus laboratory may in practice answer to a state radiation-control program rather than to the NRC directly.

For a researcher, the practical consequences are concrete: using licensed material requires an authorized user, training, dosimetry, inventory and leak-test records, and waste procedures, all typically overseen by the institution’s radiation safety officer and radiation safety committee. Research on novel reactor concepts is also affected indirectly, because test data and code validation must eventually support an NRC licensing review.

The Department of Energy (DOE)

DOE plays two roles. First, it is a major federal funder of nuclear engineering research (see below). Second, it is itself an owner and regulator: it operates the national laboratories and sets safety requirements for its own nuclear facilities, which are outside the NRC’s licensing authority. Work performed at DOE sites carries site-specific access, security and safety rules. Foreign national participation in DOE-funded work can be affected by DOE policies such as the country-of-concern restrictions discussed in CASRAI’s guide on the DOE Sensitive Country List and foreign national access.

Export controls and technology transfer

Nuclear technology is among the most tightly export-controlled subject areas in research, and the rules cut across several agencies:

• 10 CFR Part 810 (DOE). Implements section 57b.(2) of the Atomic Energy Act and controls the export of unclassified nuclear technology and assistance, including help with nuclear fuel-cycle activities, power plants and research and test reactors. Part 810 sorts activities into those generally authorized by the Secretary of Energy and those requiring specific authorization.
• 10 CFR Part 110 (NRC). Governs exports and imports of nuclear equipment and materials under NRC jurisdiction.
• The Export Administration Regulations (EAR, Commerce). Cover dual-use items and technology, including nuclear-related items listed on the Commerce Control List. Classification relies on determining the item’s ECCN; see the ECCN determination process.
• The International Traffic in Arms Regulations (ITAR, State). Cover defense articles and services on the US Munitions List, which includes nuclear weapons-related articles.

The practical effect for universities is that sharing technical data, hosting foreign collaborators, shipping samples or travelling with controlled information can all require analysis or a license, and the fundamental-research exclusion that frees much academic work from export controls does not remove every obligation. Research offices should treat nuclear projects as high-attention reviews. CASRAI’s guides on ITAR and EAR compliance for university research and how export control classification works explain the underlying decision process, and research-security rules for federally funded work add further obligations.

International oversight

Outside the United States, the International Atomic Energy Agency (IAEA) sets safety standards and administers safeguards that verify nuclear material is not diverted to weapons use, and the OECD Nuclear Energy Agency coordinates research cooperation among member countries. National regulators in other countries play the NRC’s role locally, and international collaborations must satisfy each partner’s rules.

Who funds nuclear engineering research

Unlike many engineering fields, nuclear engineering research funding is concentrated in a few federal sources:

• DOE Office of Nuclear Energy (DOE-NE). A primary funder of civilian reactor, fuel-cycle and nuclear materials research. Its Nuclear Energy University Programs (NEUP), administered through Idaho National Laboratory, fund university research and infrastructure such as equipment purchases and facility upgrades, and the department has also supported undergraduate scholarships and graduate fellowships for nuclear energy students.
• DOE Office of Science. Funds nuclear physics, fusion energy sciences and basic energy sciences, which supply the data and materials science that nuclear engineers build on. See CASRAI’s guides on writing a DOE Office of Science proposal narrative and DOE Energy Frontier Research Centers.
• ARPA-E. Funds higher-risk energy technology concepts; see how ARPA-E differs from DOE’s standard grant programs.
• NNSA, the Department of Defense and the Navy. Support nonproliferation, naval propulsion and radiation-effects research, often with security and publication restrictions.
• The NRC. Sponsors confirmatory safety research to support its regulatory decisions.
• The National Science Foundation (NSF). Supports fundamental engineering and physics research relevant to the field; see the NSF versus DOE grant requirements comparison for how the two agencies’ rules differ.
• Industry and international funders. Utilities, reactor vendors and advanced-reactor developers sponsor applied work, and agencies abroad support national nuclear research programs.

To see what DOE has funded, CASRAI’s DOE award search guide explains how to look up awards. Funding for nuclear projects often arrives with unusual conditions: facility access agreements, restrictions on foreign-national participation, security review of publications, and requirements to use specific national-lab user facilities.

Journals and professional societies

Core journals for the field include Nuclear Science and Engineering and Nuclear Technology (both published for the American Nuclear Society), Annals of Nuclear Energy, Nuclear Engineering and Design, Journal of Nuclear Materials, Progress in Nuclear Energy and, for fusion, Nuclear Fusion. The American Nuclear Society is the main US professional society, holding annual and topical meetings where much of the community’s research is first presented. Other relevant organizations include the American Society of Mechanical Engineers (for codes and standards such as pressure-boundary requirements), the IEEE Nuclear and Plasma Sciences Society (for detectors and instrumentation) and, internationally, the IAEA and the OECD Nuclear Energy Agency.

Education and careers

Nuclear engineering is offered as a bachelor’s, master’s and doctoral degree at a limited number of universities, and it is also commonly studied as a specialization within mechanical, chemical or physics programs. Undergraduate curricula combine mathematics, physics and engineering science with reactor physics, thermal hydraulics, radiation detection and shielding. Research-oriented careers generally require a master’s or PhD, structured as coursework plus a thesis or dissertation. Typical employers include national laboratories, reactor vendors and advanced-reactor developers, electric utilities, the NRC and DOE, the Navy’s nuclear propulsion program, medical physics and isotope producers, and universities. Many positions require US citizenship and a security clearance, which affects who can be hired into some roles and which students can participate in some funded projects.

Why this matters for research administration

Few fields generate as many administrative touchpoints per project. A single nuclear engineering award may involve a radiation safety review and materials license coverage, a facility use agreement with a national laboratory, an export-control classification, a foreign-national access review, controlled-data handling in line with NIST SP 800-171 and CUI requirements, and sponsor-specific publication review. Pre-award staff should flag these early, because they affect budget (dosimetry, shielded space, waste disposal), schedule (licensing amendments and access approvals can take months) and who can be listed on the project. Post-award, inventories of radioactive and nuclear materials are subject to audit by both regulators and sponsors. Building these checks into proposal intake is far cheaper than discovering them after an award has been accepted.

Frequently asked questions

What is nuclear engineering in simple terms?

It is the engineering discipline that designs and operates systems based on nuclear reactions and radiation, mainly nuclear power plants, but also radiation-based medicine, industrial radiation applications, space and naval reactors, waste management and nuclear security.

What do nuclear engineers do?

They analyze and design reactors and fuel, model neutron and heat behavior, assess safety and risk, develop radiation detection and shielding, manage radioactive waste, and support regulatory licensing. Researchers among them also test materials and fuels under irradiation and develop the simulation codes the field relies on.

What is the difference between nuclear engineering and nuclear physics?

Nuclear physics seeks to understand the nucleus and nuclear interactions; nuclear engineering applies that knowledge to build and operate systems. The fields share data and facilities, and many researchers move between them. See CASRAI’s guide on what nuclear physics is.

Who regulates nuclear research in the United States?

The NRC regulates civilian nuclear facilities and materials, including university research reactors, while DOE regulates its own facilities. Agreement States regulate certain materials in place of the NRC, and export of nuclear technology is controlled by DOE (Part 810), the NRC (Part 110), Commerce (EAR) and State (ITAR), depending on the item.

Do export controls apply to university nuclear research?

They can. Fundamental research that is openly published is often exempt from some export-control rules, but nuclear technology is subject to specific authorization requirements such as Part 810, and sharing controlled technical data or hosting foreign collaborators may still need review. Consult your institution’s export-control office before sharing nuclear-related technical information.

Who funds nuclear engineering research?

Major sources include DOE (the Office of Nuclear Energy and the Office of Science), ARPA-E, NNSA, the Department of Defense, the NRC, NSF and industry.

What degree do you need to become a nuclear engineer?

A bachelor’s degree in nuclear engineering or a closely related engineering or physics field is the usual entry point, and research roles typically require a master’s or PhD.

Related CASRAI resources

Nuclear engineering is one of many disciplines mapped in CASRAI’s overview of the branches of science. For the engineering fields it draws on, see the guides to mechanical, chemical and electrical engineering, and for the science side, nuclear physics and particle physics. On compliance and funding, see ITAR and EAR compliance, the DOE Sensitive Country List and the radiation safety officer role.