Staff Nuclear Engineer

The role

You will provide technical expertise across the nuclear design and analysis of Kaleidos. You will lead complex projects from requirements definition through model development, analysis, and regulatory documentation.

What you will do

• Provide technical leadership across reactor physics, core performance, shielding, dose and activation, thermal-hydraulics, safety analysis, I&C, and reactor operations.
• Own complex nuclear engineering projects from requirements capture through final documentation.
• Perform and guide analyses of criticality, reactivity control, shutdown margin, power distribution, depletion, temperature feedback, radiation transport, dose, activation, and shielding performance.
• Develop, review, and improve high-fidelity neutron and radiation transport models.
• Translate analytical results into actionable requirements and design decisions.
• Lead multidisciplinary technical trades.
• Establish and improve practices for model verification and validation, peer review, and technical documentation.
• Ensure analytical assumptions, limitations, uncertainties, margins, and conclusions are documented.
• Develop analytical methods, workflows, and tools.
• Collaborate with reactor systems, thermal, mechanical, electrical, test, operations, safety, and regulatory teams.

Required qualifications

• Bachelor’s degree in nuclear engineering or a related technical discipline from an accredited institution.
• 8+ years of relevant nuclear engineering experience across reactor design, analysis, testing, licensing, safety, or operations.
• Demonstrated experience owning complex nuclear engineering projects involving multiple technical disciplines and stakeholders.
• Deep knowledge of neutron transport theory, Monte Carlo simulation methods, nuclear data, and statistical convergence.
• Professional experience developing and applying MCNP, OpenMC, or comparable neutron and radiation transport models.
• Strong understanding of reactor physics concepts, including criticality, reactivity coefficients, depletion, power distribution, shutdown margin, neutron and gamma transport, and uncertainty analysis.
• Experience translating analytical results into reactor design decisions, technical requirements, safety conclusions, or regulatory documentation.
• Experience developing or reviewing technically rigorous analysis methodologies, models, calculation packages, or engineering standards.
• Familiarity with model verification and validation, configuration control, peer review, and nuclear software quality practices.
• Demonstrated ability to operate independently on technically complex problems and drive work from definition through technical closure.
• Strong written and verbal communication skills.
• Must be mission driven and willing to support extended hours when needed.

Nice to have

• Master’s degree or Ph.D. in nuclear engineering or a related technical discipline.
• Subject-matter expertise in safety analysis, shielding, radiation dose and activation, instrumentation and controls, reactor operations, thermal-hydraulics, or radioactive-material transportation.
• Experience with high-temperature gas-cooled reactors, microreactors, advanced reactors, or first-of-a-kind nuclear systems.
• Experience with SCALE, Serpent, Shift, Griffin, MOOSE-based applications, or similar nuclear analysis tools.
• Proficiency with Python or another language used for simulation automation, model generation, and analysis post-processing.
• Experience with coupled neutronics and thermal-hydraulics or other multiphysics analyses.
• Familiarity with DOE authorization processes, NRC licensing, nuclear industry codes and standards, or regulatory safety analysis.
• Experience supporting reactor testing, commissioning, startup, or operational readiness.
• Experience developing analytical methods, technical standards, or nuclear engineering capabilities within a growing engineering organization.
• Demonstrated experience mentoring engineers and providing technical review across complex engineering programs.

Benefits

• Substantial incentive stock plan for all full-time employees.
• Medical: 100% up to base silver level plan for employee + 50% dependents, offers up to Platinum plans.
• One Medical: Sponsored memberships for employees and their dependents.
• Vision: 100% top tier plan coverage + 50% for dependents.
• Dental: 100% top tier plan coverage, orthodontia extra, 50% for dependents.
• Voluntary life, accident, hospital, critical illness, commuter and FSA/HSA are offered as employee contributed benefits.
• 8-weeks of paid parental leave for all parents.
• Additional paid pregnancy leave for CA employees.
• Nuclear Engineering Certificate Program: 100% covered educational program with Penn State University, for eligible employees.
• Daily catered lunch.
• Free snacks and drinks.
• Flexible PTO policy.

Before you apply

• Any job offer made will be contingent upon the applicant’s capacity to serve in compliance with U.S. export controls.

About the company

Radiant is an El Segundo, CA-based company building the world's only mass-produced, transportable nuclear microreactors. Founded in 2020, Radiant is under contract to deliver power to the U.S. Army, Navy and Air Force.