Neutronics engineerSalary, qualifications, licensing and career path, 2026 edition
A neutronics engineer models how neutrons travel, scatter, get absorbed and multiply, from the heart of a nuclear reactor core to the far side of a shielding wall. It is the most computational role in the nuclear engineering family, built on specialized software tools, transport codes, cross-section libraries and Monte Carlo methods, and it cuts across everything neutrons touch: fission cores, fusion blankets, medical radioisotope production systems, nuclear rocket propulsion systems and radiation shielding.
Neutronics engineers earn a median of around $135,000 in the United States and roughly £53,000–£71,000 at mid to senior level in the UK, rising past £110,000 for a transport authority. Fusion, advanced-reactor and space-nuclear work sits at the top of the range because the skills are scarce and critical for delivering innovative solutions in clean energy.
No single licence is required. What gates the work is competence on the transport methods and their safety use: a PE licence or SQEP designation, security clearance, and formal authorisation to approve criticality and shielding calculations, ensuring verification successful and compliance with applicable company health and safety protocols.
The role at a glance
Everything an employer will ask about in the first fifteen minutes of a screening call.
- Also called
- Neutron transport engineer · criticality safety engineer · shielding engineer · reactor physics (methods) engineer · radiation transport analyst
- Entry qualification
- BSc/MSc in nuclear engineering, physics, or engineering science; a PhD in neutron transport, computational physics, or reactor physics is common for methods and research posts.
- Typical entry pay
- $80,000–$112,000 (US) · £33,000–£39,000 (UK graduate), influenced by local job market factors and other objective business considerations
- Senior / authority pay
- $156,000–$215,000 (US) · £78,000–£112,000 (UK principal or transport authority)
- Contract day rates
- £540–£720 for transport and shielding analysis; £620–£820 for criticality safety and methods work outside IR35; $100–$160/hr US neutronics support
- Professional gate
- US: PE licence for engineering grades; internal approval authority for criticality and shielding following security verification. UK: SQEP designation, normally with CEng or CPhys.
- Security
- UK BPSS minimum, SC common, DV for defence and space-nuclear work. US: unescorted access authorisation under 10 CFR 73, plus citizenship for NRC, DOE, naval nuclear reactors, and other federal government contractor posts.
- Where the work sits
- Reactor vendor, national laboratory, fusion programme, criticality-safety group, or medical and industrial isotope work. Strongly hybrid-friendly; almost entirely computational.
- Travel
- Low. This is one of the most office- and compute-based roles in the sector; occasional site visits for shielding surveys or as-built confirmation.
- TRX segments
- New technology development · Fusion · Fuel handling & fuel cycle · Decommissioning & dismantling · Radioactive waste management · Large new build · Advanced nuclear fuel technologies · Accelerated reactor design development
Six versions of the same job title
"Neutronics engineer" is defined by the neutron source you model, and that changes the physics, the codes and the pay. Bar shows relative hiring volume across TRX's 2026 desk activity.
New technology development
Core neutronics for SMRs and advanced reactors: criticality, depletion, control worth and reactivity feedback for cores using novel geometries, coolants and fuels. TerraPower, X-energy, Kairos, Rolls-Royce SMR, Holtec, Oklo.
Fusion
Blanket and shield neutronics for a 14 MeV source: tritium breeding, activation, nuclear heating and shielding of magnets and structures. ITER, STEP, Commonwealth Fusion, Tokamak Energy, TAE, Helion.
Fuel handling & fuel cycle
Criticality safety across enrichment, fabrication, transport and storage, including burnup credit and the HALEU transition, which raises enrichment and changes every criticality margin.
Decommissioning & dismantling
Shielding, dose and activation analysis for dismantling degraded plant, plus criticality safety of fuel debris in disrupted geometry. Sellafield, Dounreay, Fukushima Daiichi.
Radioactive waste management
Criticality control and shielding for packaging, interim storage and geological disposal, including the source-term and burnup-credit methods that make packing efficient and safe.
Large new build
Shielding design, ex-core neutronics and criticality for spent-fuel pools and handling systems on gigawatt plants under construction.
What the week actually looks like
A composite day for a mid-level neutronics engineer at a reactor vendor, fusion programme or national lab, working a transport model. Compute-heavy office, hybrid. Deadlines and long-running jobs shape the rhythm — noted below.
What neutronics engineers are paid in 2026
Bars show the 25th to 90th percentile of base salary. The marker is the median. Switch currency to move between the US and UK markets, which behave differently.
How neutronics compares to adjacent roles
US figures. Nuclear engineer median is BLS OEWS May 2025; the neutronics ranges are TRX market analysis, because these specialisms are not separately coded by BLS.
| Occupation | Median | P10 | P90 | What moves the number |
|---|---|---|---|---|
| Neutronics engineer | $135,000 | $89,000 | $215,000 | Fusion and advanced-reactor transport, criticality methods, PhD for research work, clearance |
| Nuclear engineer (parent SOC) | $133,970 | $93,000 | $196,000+ | PE licence, safety case authorship, clearance |
| Reactor core analyst | $132,000 | $87,000 | $208,000 | Methods qualification, transient and DNB work, licensing analysis |
| Reactor physicist | $128,000 | $84,000 | $198,000 | Physics-test authorisation, core-follow, advanced-reactor validation |
Sources: US BLS OEWS May 2025 for the coded nuclear-engineer occupation; TRX market analysis Q3 2026 for the specialism ranges. Neutronics engineers are coded as nuclear engineers by BLS, so no separate federal median exists.
Fusion and advanced-reactor neutron transport
Modelling a 14 MeV fusion neutron source, or a fast-spectrum or molten-salt reactor core, requires specialized physics and computational methods possessed by few experts, and the private fusion and advanced nuclear reactor sector is aggressively recruiting all qualified candidates. Expect a significant salary premium over conventional fission shielding and transport work.
Criticality safety engineering with burnup credit expertise
The rarest and most sought-after neutronics skill, essential across nuclear fuel cycle operations, radioactive waste management, decommissioning, and transport safety, made even more critical by the transition to HALEU fuel with higher enrichment levels.
Neutron transport methods and nuclear data proficiency
Engineers who deeply understand nuclear cross-section libraries, data processing, and can validate and qualify neutron transport methods, not just operate simulation codes, are in high demand across every nuclear segment, because incorrect nuclear data processing can jeopardize entire safety cases.
Three ways in, and only one of them starts with a nuclear degree
Neutronics is the most physics-and-computation-heavy nuclear role, so a physics or computational background is often the straightest line in, and a PhD genuinely opens doors rather than just adding a title. Many neutronics engineers come from computational physics, medical physics or accelerator backgrounds.
Physics or engineering graduate, United Kingdom
Five to nine years to chartered and SQEP; add two to four for a PhD.
Physics or nuclear PhD, methods and research track
Four to eight years post-PhD to principal.
Career changer
Twelve to thirty months, and the route the nuclear sector is actively recruiting for in 2026.
Are you actually ready to compete for a neutronics role?
Everything above tells you what the market pays and what it asks for. It does not tell you how your CV reads against the other engineers applying for the same transport, criticality or fusion post, and in a field where methods depth and specific code experience decide offers, that is the part that costs candidates the job.
Free resume scoring on avua, TRX's job search and application platform. Your score is yours; it is not shared with employers.A strong computational CV can still miss the shortlist if it does not show qualified, safety-relevant transport work. The gap is the part you can fix.
Illustrative figures based on TRX shortlisting patterns across neutronics vacancies. Your own score is generated by avua from your CV and the role you are targeting.
The credentials that actually gate the work
Neutronics is not a licensed profession. What is controlled is who may approve a criticality or shielding calculation and the method behind it, decided by professional registration, employer competence assessment and internal approval authority.
| Credential | Jurisdiction | Required for | Time | Notes |
|---|---|---|---|---|
| Professional Engineer (PE) | United States | Stamping engineering deliverables; utility and vendor grades | ~4 yrs | FE exam, four years under a PE, then the PP exam. Not required for pure research posts. |
| Criticality / shielding approval authority | US / UK | Approving criticality safety and shielding calculations | Role-specific | Internal, granted once competence for a defined scope is demonstrated. |
| Unescorted access authorisation | United States | Working inside a protected area unescorted | 4–10 wk | 10 CFR 73 background check, psychological assessment, fitness for duty. Needed less often for compute-based work. |
| CEng or CPhys registration | UK / Commonwealth | Senior technical grades; expected for a transport authority | 4–7 yrs | Via the Nuclear Institute / IMechE (CEng) or the Institute of Physics (CPhys). |
| SQEP designation | UK | Signing or approving neutronics safety deliverables | Role-specific | Employer-assessed against a defined scope; not portable without reassessment. |
| BPSS / SC / DV clearance | UK | Site access; defence, fusion and space-nuclear work | 2–20 wk | DV can take five months. Current clearance is a real competitive advantage. |
| Radiation protection training | All | Any controlled or supervised area entry | 1–5 days | Site induction plus dosimetry; needed less often in a compute-based role. |
| Citizenship | US / France / others | NRC, DOE, naval and national-laboratory posts | — | US citizenship is required for federal and naval work; not for NRC-regulated private firms. |
Requirements change with programme and site. Confirm the specific scope with the employer before assuming a credential transfers.
What appears on a 2026 neutronics engineering shortlist
Drawn from the neutronics requirement specifications TRX has worked in the last twelve months, ordered by how often each is a hard filter.
Named on the specification
- Monte Carlo transport — MCNP, Serpent or OpenMC, including variance reduction for deep-penetration shielding in the commercial nuclear power industry, conveying detailed technical data
- Deterministic transport — DENOVO, PARTISN, ATTILA or equivalent for large fixed-source and coupled problems in varied engineering environments, supporting multiple engineering disciplines
- Depletion and burnup — Coupling transport to depletion (Serpent, SCALE/ORIGEN) for isotopics, burnup credit, and fuel utilization strategies essential as nuclear energy grows
- Criticality safety — SCALE/KENO or MONK, ANSI/ANS-8 or the UK equivalent, and double contingency, supported by a financial background investigation where required
- Nuclear data — ENDF cross-section libraries, processing, temperature treatment and self-shielding, ensuring compliance with an agreement explicitly encompasses safety standards and BWXT's advanced technologies
- Shielding and dose — Source-term definition, dose-rate calculation, and defensible variance-reduction strategy maintaining a healthy work life balance, often related to precision manufactured components
What decides between two shortlisted candidates
- Convergence judgement — Knowing when a tally is genuinely converged and when the statistics are lying to you, critical for national origin diverse teams
- Writing — A criticality or shielding case is only as strong as the argument that defends it, especially when the agency exists prior to project start
- Fusion or fast-spectrum experience — Modelling a 14 MeV or fast source, the scarce skill across fusion and advanced reactors with engaging and challenging projects
- Method and data depth — Being able to qualify a method or validate a library, not just run an approved deck, important for core neutronics design engineer roles
- HPC and scripting — Python and cluster fluency, because production neutronics is a compute workflow that supports a healthy work life balance
- Second language — French for ITER, CEA and Framatome work; useful across fusion and export programmes in the commercial nuclear power industry
The 2026 demand map
Neutronics is the most cross-cutting nuclear discipline, so demand comes from every direction at once: fission, fusion, fuel cycle, waste and defence. Because the work is compute-based, location flexibility matters less here than in almost any other nuclear role.
| Programme | Location | Phase in 2026 | Engineering demand |
|---|---|---|---|
| TerraPower Natrium | Wyoming, US | Reactor build to follow | Fast-spectrum core neutronics, a scarce Western skill |
| X-energy Xe-100 + TRISO-X | Texas & Tennessee, US | Design, licensing and fuel fabrication | Pebble-bed depletion and criticality; TRISO fuel neutronics |
| Kairos Hermes / Oklo Aurora | Tennessee & Idaho, US | Construction and licensing | Molten-salt and fast-microreactor neutronics |
| Rolls-Royce SMR / Holtec SMR-300 | UK & US | Licensing | Core neutronics, control worth and criticality for novel PWRs |
| ITER / STEP | France & UK | Assembly and design | Blanket neutronics, tritium breeding, activation and magnet shielding |
| Commonwealth Fusion / Tokamak Energy / Helion | US & UK | Prototype build | Private-fusion blanket and shield neutronics, hiring hard |
| HALEU fuel cycle | US | Enrichment and fabrication scale-up | Criticality safety at higher enrichments across the fuel cycle |
| Sellafield / Fukushima Daiichi | UK & Japan | Retrieval and characterisation | Shielding, dose and fuel-debris criticality in disrupted geometry |
| Nuclear Waste Services / geological disposal | UK & global | Packaging and repository design | Criticality control, burnup credit and shielding for waste packages |
| Naval and space nuclear | US & UK | Design and prototype | Reactor and shielding neutronics for compact and space reactors (clearance-gated) |
Programme phases move. Confirm current status before making a relocation decision; TRX tracks these weekly.
Neutronics is the most portable core skill in nuclear engineering.
Because the work is computational and the same transport codes serve fission, fusion, medical, waste and defence sectors, neutronics engineers move between segments more freely than any other core-engineering role, and roles are more often hybrid or remote-friendly. That breadth is protective: when one segment slows, another is usually hiring the same specialized skills.
Why experienced neutronics engineers have leverage in the nuclear workforce.
Deep transport, criticality safety and nuclear-data expertise takes years to build and is concentrated in a generation now retiring, exactly as fusion and advanced reactors create demand for it faster than universities produce it. Mid-career neutronics engineers who can qualify methods and validate nuclear data are among the most contested hires in the sector, with competitive base salary range and strong business and welcome candidates outlook.
Adjacent and onward roles
Neutronics is the methods core of the cluster and connects out to physics, analysis and shielding-heavy segments. These are the moves TRX sees most often.
Questions we get asked every week
How much does a neutronics engineer earn in 2026?
In the United States the salary range spans from about $80,000 for a graduate to $135,000 at the median, with senior principals and transport authorities earning past $215,000. In the UK, salaries range from £33,000–£39,000 for a graduate to £83,000–£112,000 for a transport authority. Fusion, advanced-reactor, and space-nuclear neutronics roles command the highest pay because these skills are scarce, and contract criticality safety and methods specialists typically bill £620–£820 a day outside IR35.
Do you need a professional licence to work as a neutronics engineer?
No industry-wide licence exists. A US Professional Engineer (PE) licence is often expected for engineering sign-off roles but not for pure research positions. What actually controls access to responsible work is internal criticality and shielding approval authority and, in the UK, Suitably Qualified and Experienced Person (SQEP) designation for a defined neutronics scope, ensuring that those who approve criticality or shielding calculations are formally competent.
Can you become a neutronics engineer without a nuclear engineering degree?
Yes. Backgrounds in physics, computational physics, medical physics, or accelerator physics map directly onto neutron transport modelling, and many neutronics engineers transition from these fields. A PhD is common for advanced methods and research posts but is not mandatory to enter through criticality safety or shielding pathways. The specialized expertise lies in mastering the neutron transport toolset and understanding the nuclear safety framework, both of which are learned on the job or via an MSc program.
Is neutronics a promising career in 2026?
Demand is robust and unusually broad, as neutronics expertise spans fission, fusion, fuel cycle management, radioactive waste, decommissioning, and defense sectors, all actively hiring. These skills are among the most portable and hybrid-friendly in the nuclear industry. The honest caveat: the most advanced, highest-paid roles (fusion transport, methods qualification, fast-spectrum core design) require years of experience, and some of the top-paying niches (naval and space nuclear) are restricted by citizenship and security clearance requirements.
What distinguishes a neutronics engineer from a reactor physicist?
A neutronics engineer specializes in computational modelling of neutron transport, cross-section data, shielding design, and criticality safety, often for reactors, blankets, or packages still in the design or analysis phase. A reactor physicist focuses on the overall physics behavior of an operating core, including reactivity, kinetics, core-follow, and physics testing on live plant systems. Both share fundamental nuclear physics principles and many computational codes; the difference lies in transport-method depth versus real-core operational behavior. Many professionals perform both roles at different career stages.
Which neutronics skills are most in demand in 2026?
Fusion and fast-spectrum neutron transport leads the demand, driven by private fusion startups and advanced reactor developers. Close behind is criticality safety with burnup credit expertise, essential across fuel cycle operations, waste management, and decommissioning, increasingly critical due to HALEU fuel enrichment transitions. Proficiency in Monte Carlo transport codes (MCNP, Serpent, OpenMC), coupled with depletion modelling and nuclear data processing, is nearly mandatory, while deterministic transport methods remain a strong differentiator.
We only recruit in nuclear. That is the whole point.
TRX works across large new build, fusion, new technology development, decommissioning, radioactive waste management and nuclear medicine, in 14+ countries. Send us your CV and we will tell you honestly which core-engineering path your experience actually fits, and what it is worth.