Senior Nuclear Engineer Location:

El Segundo, CA Employment Type:

Full-Time | On-Site About the Role We are seeking a Senior Nuclear Engineer to play a critical role in the design, analysis, and commercialization of next-generation nuclear reactor technology. This position will focus heavily on reactor physics, neutronics modeling, safety analysis, and simulation , with responsibility for developing and validating the analytical methods used to predict reactor behavior across normal operations and transient conditions. The Senior Nuclear Engineer will work closely with multidisciplinary engineering teams spanning nuclear, thermal-hydraulics, mechanical, controls, software, testing, and regulatory engineering. This is an opportunity for an engineer who wants to move beyond maintaining legacy nuclear systems and help design, analyze, test, and ultimately deploy a new reactor platform. Key Responsibilities

• Own reactor physics and neutronics modeling supporting reactor design and transient safety analysis.
• Perform calculations involving reactivity coefficients, kinetics parameters, neutron flux, energy deposition, control worth, criticality, and core performance .
• Develop and maintain high-fidelity computational models of reactor behavior.
• Perform Monte Carlo neutron transport calculations using tools such as MCNP, OpenMC, Serpent, SCALE, or equivalent platforms .
• Evaluate modeling assumptions, uncertainties, margins, and conservatisms.
• Support development and validation of integrated reactor simulation and Digital Twin environments.
• Participate in Verification & Validation (V&V) of analytical models and simulation tools.
• Support reactor safety analyses covering normal operation, anticipated operational occurrences, and accident/transient scenarios.
• Collaborate with thermal-hydraulics, mechanical, controls, instrumentation, and software teams to integrate nuclear analyses into the overall reactor design.
• Perform or review analyses involving shielding, radiation transport, activation, dose, and radiation detection as needed.
• Translate complex analytical results into clear engineering requirements and design decisions.
• Prepare calculation packages, technical reports, design documentation, and regulatory-supporting analyses.
• Participate in technical and design reviews and challenge assumptions when necessary.
• Support testing, commissioning, and reactor operations activities as the program progresses.
• Mentor less-experienced nuclear engineers and contribute to the development of engineering methods and best practices. Required Qualifications
• Bachelor's degree in Nuclear Engineering, Nuclear Physics, or a closely related engineering discipline .
• 4+ years of professional nuclear engineering experience .
• Strong background in reactor physics and neutron transport .
• Hands-on experience with Monte Carlo nuclear engineering tools such as: o MCNP o OpenMC o Serpent o SCALE o or comparable reactor physics software
• Experience developing, documenting, and defending engineering analysis methods and assumptions.
• Strong understanding of nuclear engineering first principles.
• Ability to independently own technically complex engineering problems from initial analysis through final documentation.
• Strong technical communication skills and ability to work effectively across engineering disciplines. Preferred Qualifications
• Master's degree or PhD in Nuclear Engineering or a related discipline.
• Advanced experience in reactor kinetics and transient analysis .
• Knowledge of thermal-hydraulic principles and coupled neutronics/thermal-hydraulic analysis.
• Experience with advanced reactors, microreactors, SMRs, research reactors, naval nuclear systems, or other high-performance reactor programs.
• Experience supporting nuclear safety analysis or licensing activities.
• Knowledge of shielding, radiation transport, activation, and dose analysis.
• Experience with Python or another programming language used for engineering analysis and automation.
• Experience developing or validating simulation environments and Digital Twins.
• Familiarity with DOE and/or NRC nuclear requirements and regulatory environments.
• Experience supporting reactor testing, commissioning, or operations.

What Success Looks Like The strongest candidate won't simply run existing analysis tools. They will understand the physics behind the models , challenge assumptions, identify where analytical conservatism is appropriate, and translate complex nuclear analysis into engineering decisions. We're looking for someone who can move comfortably between: Physics → Modeling → Simulation → Validation → Hardware → Reactor Safety This is a hands-on engineering role for someone who wants ownership and is energized by solving difficult problems at the intersection of nuclear physics, software, hardware, and reactor design. Ideal Candidate Profile The ideal candidate is likely coming from an advanced reactor developer, national laboratory, nuclear technology company, naval nuclear program, reactor vendor, or highly technical nuclear engineering organization .

Particularly relevant backgrounds include:

• Advanced reactor / microreactor development
• Reactor core physics
• Neutronics
• Reactor kinetics
• Monte Carlo neutron transport
• Nuclear safety analysis
• Reactor simulation
• Nuclear Digital Twins
• Shielding and radiation transport
• Reactor testing and operations Above all, we want an engineer who takes end-to-end ownership , moves quickly without sacrificing technical rigor, and wants to help bring a new nuclear reactor from engineering models into the real world.

Pay:

$160,000.00 - $220,000.00 per year

Benefits:

Dental insurance Health insurance Parental leave Relocation assistance Vision insurance

Work Location:

In person