Mechanical Engineer, Fluid Systems – 2026 New Graduate

Job Description

Mechanical Engineer, Fluid Systems – 2026 New Graduate | Radiant

The Tone:
This is an early career role at Radiant, located in El Segundo, CA. Radiant is building the Kaleidos Development Unit (KDU), the United States’ first new fueled reactor design in over 50 years, with the mission to rapidly deploy nuclear microreactors for clean energy in remote locations. This position contributes directly to the design, assembly, and testing of KDU fluid subsystems, advancing the unit’s readiness for fueled operations and supporting Radiant’s groundbreaking work in nuclear energy. The successful candidate will take ownership of projects vital to the KDU’s development.

The TL;DR
• Role: Early Career
• Type: Full-time
• Location: In-person, El Segundo, CA
• Pay: $95000–$105000 yearly
• Team: KDU Engineering team
• Mission: To take ownership of projects vital to advancing KDU’s readiness for fueled operations.
• Tech Stack: CAD, analysis software, lab instrumentation

What You’ll Actually Do
• Design & Test: Design, analyze, and test KDU fluid subsystems.
• Project Ownership: Own deliverables from concept through build and validation, with guidance from senior engineers.
• Collaboration: Integrate designs and resolve complex technical challenges by collaborating across disciplines.
• Development Support: Support system-level testing, troubleshooting, and design iteration to accelerate KDU development.
• Communication: Communicate results effectively through design reviews, technical reports, and presentations to peers and leadership.

The Must-Haves
• Background: BS in Mechanical Engineering, Aerospace Engineering, or a related discipline, completed or expected Spring 2026, with a strong foundation in thermodynamics and fluid mechanics.
• Experience: Hands-on experience in design and build through projects, research, labs, or internships.
• Skills: Proficiency with engineering tools such as CAD, analysis software, and lab instrumentation.
• Bonus: A Master’s degree in Mechanical Engineering, Aerospace Engineering, or a related discipline (completed or in progress), prior internship or project-based experience related to fluid systems, independent problem-solving abilities, and excitement for Radiant’s mission. Knowledge of reactor physics is also helpful.