Senior Reactor Engineer

The role

You will lead the testing and verification of critical components, mechanisms, and subsystems within the Kaleidos microreactor. You will work with nuclear, mechanical, thermal, controls, and test engineering teams to ensure hardware meets functional, performance, and safety requirements.

What you will do

• Lead testing and verification of reactor components, mechanisms, and subsystems.
• Own test activities from requirements definition and planning through execution, data analysis, and documentation.
• Develop test plans, procedures, instrumentation requirements, and acceptance criteria.
• Collaborate with nuclear, mechanical, thermal, and controls engineers.
• Perform engineering analyses and compare experimental results against analytical predictions.
• Review and technically approve test procedures, verification reports, and engineering documentation.
• Support reactor operations, commissioning, and integrated testing.
• Investigate hardware failures and test anomalies to identify root causes.
• Translate test findings into design improvements.

Required qualifications

• Bachelor's degree in nuclear engineering, mechanical engineering, or a related technical discipline from an accredited institution.
• 5+ years of relevant experience in reactor engineering, hardware testing, design verification, or complex hardware development.
• Demonstrated experience developing and executing component or subsystem tests.
• Strong engineering fundamentals in mechanical systems, heat transfer, materials, instrumentation, and component performance.
• Understanding of reactor operating principles, safety functions, and component-level performance requirements.
• Experience developing technical procedures, establishing acceptance criteria, and evaluating results against engineering requirements.
• Experience troubleshooting hardware failures, conducting root cause investigations, and implementing design improvements.
• Ability to interpret engineering drawings, specifications, and technical requirements.
• Must be mission driven and willing to support extended hours when needed.
• Must work 100% onsite at Radiant's El Segundo headquarters.

Nice to have

• Master's degree or Ph.D. in nuclear engineering, mechanical engineering, or a related technical discipline.
• Experience with reactor components, core assemblies, reactivity control mechanisms, instrumentation, or safety-critical hardware.
• Experience with high-temperature gas-cooled reactors, microreactors, advanced reactors, or first-of-a-kind nuclear systems.
• Familiarity with reactor physics, thermal-hydraulics, nuclear safety, and reactor operations.
• Experience supporting reactor testing, commissioning, startup, or operational readiness.
• Experience with test instrumentation, data acquisition systems, and testing under demanding thermal, mechanical, or environmental conditions.
• Proficiency with Python, MATLAB, or similar engineering tools for test automation and analysis.
• Familiarity with DOE authorization processes, NRC licensing, nuclear industry standards, or nuclear quality assurance requirements.

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.