Senior Mechanical Engineer, Fluid Systems

About the role

Radiant, an El Segundo‑based startup developing portable nuclear microreactors, is looking for a Senior Mechanical Engineer to lead the design, build, and production of the Kaleidos reactor’s fluid systems. You will own the primary loop and power conversion loop that transform reactor heat into electricity, playing a pivotal role in delivering the first commercial microreactor in over five decades.

Key responsibilities

• Lead end‑to‑end engineering of fluid system components such as compressors, valves, and heat exchangers.
• Conduct thermal‑hydraulic and fluid dynamics analyses using hand calculations and finite element tools.
• Perform trade studies to optimize system performance and meet program requirements.
• Develop manufacturing, assembly instructions, and test plans.
• Create and manage the Bill‑of‑Materials (BOM) and supplier relationships.
• Schedule sub‑assembly design, manufacturing, and testing activities.
• Execute risk analysis (FMEA) for all subsystems.
• Collaborate with cross‑functional engineers, providing clear technical feedback.

Required profile

• Bachelor’s degree in Mechanical, Materials, Aeronautical, Civil or Structural Engineering.
• 4+ years of experience designing, building, and testing fluid systems.
• Proven ability to perform complex thermal and fluid analyses.
• Experience with component selection, vendor management, and testing.

Required skills

• Fluid dynamics
• Thermodynamics
• Heat exchanger design and analysis
• Piping design
• Finite element analysis (FEA)
• Hand calculations for thermal growth
• Bill‑of‑Materials (BOM) creation
• Failure Mode Effects Analysis (FMEA)

What we offer

• Opportunity to work on groundbreaking nuclear microreactor technology.
• Impactful role shaping the first commercial reactor design in decades.
• Collaborative startup environment with rapid development cycles.