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.

Mechanical Engineer

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.

Responsibilities and Duties

• 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.

Required Qualifications and Skills

• 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.

Desired Qualifications and Skills

• 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 transfer, or dynamics.
• Familiarity with relevant industry standards (ASME, ISO, API, or similar).
• Prior nuclear experience is not required for this role.

Additional Requirements

• Willingness to work extended hours and weekends as necessary to accomplish our mission.
• Ability to work 100% onsite at Radiant’s El Segundo headquarters.

Total Compensation and Benefits

Radiant's new hire compensation package includes base salary, substantial equity grants, and comprehensive benefits. Total compensation and level are determined through a holistic evaluation of your interview performance, experience, education, and qualifications. 

Benefits and Perks for Eligible Employees:

• Stock: Substantial incentive stock plan for all full-time employees.
• Medical: 100% premium coverage for base Silver level plan for employee 50% premium coverage for dependents. Platinum plans available.
• One Medical: Sponsored memberships for eligible employees and their dependents.
• Vision: 100% premium coverage for top tier plan 50% for dependents.
• Dental: 100% premium coverage for top tier plan (including orthodontia) 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.
• Daily catered lunch. Free snacks and drinks.
• Flexible PTO policy. Remote workday allocation.
• Company and team-bonding events, happy hours and in-person camaraderie.
• Beautiful El Segundo headquarters close to the Pacific Ocean.

We are an equal opportunity employer and all qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity or expression, pregnancy, age, national origin, disability status, genetic information, protected veteran status, or any other characteristic protected by law.

Unfortunately, we are unable to provide visa sponsorship at this time.

This position involves access to technology that is subject to U.S. export controls. Any job offer made will be contingent upon the applicant’s capacity to serve in compliance with U.S. export controls.