Mechanical Engineer

Radiant is an El Segundo, CA-based startup building the world's first mass-produced, portable nuclear microreactors. The company's first reactor, Kaleidos, is a 1-megawatt failsafe microreactor that can be transported anywhere power is needed and run for up to five years without the need to refuel. Portable nuclear power with rapid deploy capability can replace similar-sized diesel generators, and provide critical asset support for hospitals, data centers, remote sites, and military bases. Radiant's unique, practical approach to nuclear development utilizes modern software engineering to rapidly achieve safe, factory-built microreactors that leverage existing, well-qualified materials. Founded in 2020, Radiant is on track to test its first reactor next year at the Idaho National Laboratory, with initial customer deliveries beginning in 2028.

Radiant is seeking a highly motivated Mechanical Engineer to join the team responsible for the design, development, and integration of critical mechanical systems for our Kaleidos product. This role involves hands-on mechanical design and analysis of complex hardware operating in demanding environments. The ideal candidate has strong first-principles understanding of structures, materials, fluids, and thermodynamics, and enjoys taking designs from concept through testing and production. Hands-on engineering experience through internships, co-op programs, research projects, or team-based design competitions (e.g., SAE, ASME, Formula SAE) is a strong advantage.

• Design, build, and test mechanical components and systems supporting Radiant's power generation and cooling platforms.
• Develop detailed mechanical designs for components and assemblies, including structural parts, housings, rotating or moving elements, and interfaces.
• Perform static and dynamic structural analyses using hand calculations and FEA tools (ANSYS, Abaqus, or equivalent) to evaluate stresses, deformations, and fatigue life.
• Prepare technical reports, design documentation, and presentation materials to support design reviews and decision-making.
• Support the build, assembly, and testing of prototype, first-article, and production hardware.

• Bachelor's or Master's degree in Mechanical Engineering or a related field.
• 2+ years of experience in mechanical design and analysis of hardware, components, or mechanical systems.
• Proficiency in CAD and FEA tools (SolidWorks, ANSYS, Abaqus, or equivalent), including working knowledge of GD&T.
• Strong problem-solving skills and the ability to clearly communicate technical concepts.

• Experience supporting power, energy, or industrial systems.
• Knowledge of material selection for high-temperature, high-load, or demanding operating environments.
• Hands-on experience with mechanical testing, instrumentation, or experimental validation.
• Exposure to one or more mechanical engineering focus areas such as structures, mechanisms, heat