Mechanical Engineer, Mechanisms – 2026 New Graduate

Job Description

Mechanical Engineer, Mechanisms – 2026 New Graduate | Radiant

The Tone:
This is an early career position at Radiant, located onsite in El Segundo, CA. Radiant is actively developing the Kaleidos Development Unit (KDU), which marks the United States’ first new fueled reactor design in over 50 years. This role offers a unique and direct opportunity to contribute to the design, assembly, and testing of critical KDU mechanisms. Joining a cross-disciplinary team, you will take ownership of projects vital for advancing KDU’s readiness for fueled operations and support Radiant’s mission to rapidly deploy nuclear microreactors for abundant, clean energy.

The TL;DR
• Role: Early Career
• Type: Full-time
• Location: In-person, El Segundo, CA
• Pay: $95000–$105000 yearly
• Team: KDU Engineering team
• Mission: This role contributes to the design, assembly, and testing of mechanisms for the Kaleidos Development Unit (KDU) to advance its readiness for fueled operations.
• Tech Stack: CAD, analysis software, lab instrumentation

What You’ll Actually Do
• Design: Contribute to the design, analysis, and testing of Kaleidos Development Unit (KDU) mechanisms.
• Own: Take ownership of engineering deliverables from initial concept through build and validation stages, guided by senior engineers.
• Integrate: Collaborate with cross-disciplinary teams to integrate designs and resolve complex technical challenges.
• Test: Support system-level testing, troubleshoot issues, and iterate on designs to accelerate KDU development.
• Communicate: Present results through design reviews, technical reports, and presentations to both peers and leadership.

The Must-Haves
• Background: Early career professional with a Bachelor’s degree in Mechanical Engineering, Aerospace Engineering, or a closely related discipline, either completed or expected by Spring 2026. This includes demonstrating a strong foundation in core engineering first principles such as thermodynamics, fluid mechanics, statics, dynamics, and strength of materials.
• Experience: Practical hands-on experience in design and build, acquired through academic projects, research, laboratory work, or internships.
• Skills: Proficiency with essential engineering tools including Computer-Aided Design (CAD) software, various analysis software applications, and standard lab instrumentation. Possess the ability to independently tackle complex engineering challenges and proactively identify necessary resources for solutions.
• Bonus: Master’s degree in Mechanical Engineering, Aerospace Engineering, or a related discipline (completed or in progress); prior internship, co-op, or project experience specifically related to mechanisms; comfort working in a startup environment that is collaborative and mission-driven; knowledge of reactor physics.