Senior Thermal CFD Engineer for Portable Nuclear Reactors

Radiant; El Segundo, Northern (CA, KY); Hybrid; USD 140,000 - 210,000; Full time

Benefits offered by this job

Stock: Substantial incentive stock

Medical: 100% up to base silver level

One Medical: Sponsored memberships

Vision: 100% top tier plan coverage

Dental: 100% top tier plan coverage

Voluntary life, accident, hospital, FS

8 weeks of paid parental leave

Daily catered lunch

Flexible PTO policy

In-person camaraderie

Beautiful El Segundo HQ

Job summary

Radiant, an El Segundo, CA startup, is seeking a Senior Thermal Modeling & Analysis Engineer to own high-fidelity CFD and thermal modeling for Kaleidos. You will analyze heat generation, gas flow, and thermal interactions across reactor systems, supporting design decisions and safety margins.

You will work across mechanical, fluid, nuclear, structures, controls, and test engineering to develop validated analytical tools and rapid design workflows, with a strong emphasis on manufacturability

Qualifications

• Bachelor’s degree in a relevant engineering or physics field.
• 5+ years of thermal/CFD or thermal-fluid analysis experience.
• Extensive experience with STAR-CCM+ or Ansys Fluent.
• Strong fundamentals in heat transfer, fluid mechanics and numerical methods.

Responsibilities

• Own thermal and CFD analyses from definition to validation and design recommendations.
• Model turbulent gas flow, conduction, convection, radiation, and multiphysics behavior.
• Evaluate steady-state and transient conditions to identify hotspots and margins.
• Define modeling assumptions, boundary conditions, and material properties.
• Translate results into engineering decisions and collaborate across teams.
• Develop reproducible workflows and reduced-order models for rapid iteration.

Skills

Thermal-fluid analysis

CFD modeling

Heat transfer

Problem solving

Cross-functional collaboration

Python scripting

Education

Bachelor’s degree in mechanical, aerospace, nuclear engineering, physics, or related field

Tools

STAR-CCM+

Ansys Fluent

Siemens NX

Python

Job description

Radiant, an El Segundo, CA startup, is seeking a Senior Thermal Modeling & Analysis Engineer to own high-fidelity CFD and thermal modeling for Kaleidos. You will analyze heat generation, gas flow, and thermal interactions across reactor systems, supporting design decisions and safety margins.

You will work across mechanical, fluid, nuclear, structures, controls, and test engineering to develop validated analytical tools and rapid design workflows, with a strong emphasis on manufacturability