Mechanical Engineer - 2026 New Grad (Fluid Systems, Mechanisms, or Structures)

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 (Fluid Systems, Mechanisms, or Structures)

Radiant is seeking a highly motivated New Graduate Mechanical Engineer to join the KDU Engineering team. You will contribute directly to the design, assembly, and testing of the Kaleidos Development Unit (KDU) - the United States' first new fueled reactor design in over 50 years. Depending on your background and interests (fluid systems, mechanisms, or structures), you will take ownership of projects that advance KDU's readiness for fueled operations, working alongside a cross-disciplinary team of engineers.

Responsibilities and Duties

• Contribute to the design, analysis, and testing of KDU subsystems (fluid systems, mechanisms, or structural components).
• Take ownership of deliverables from concept through build and validation, with guidance from senior engineers.
• Collaborate across disciplines to integrate designs and resolve technical challenges.
• Support system-level testing, troubleshooting, and design iteration to accelerate KDU development.
• Communicate results through design reviews, technical reports, and presentations to peers and leadership.

Required Skills and Qualifications

Desired Skills and Qualifications

Additional Requirements

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 :

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.