Mechanical Engineer - New Grad (Fluid Systems, Mechanisms, or

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 * BS in Mechanical Engineering, Aerospace Engineering, or a related discipline (completed or expected Spring 2026). * Strong foundation in engineering first principles, including thermodynamics, fluid mechanics, statics, dynamics, and strength of materials.

* Hands-on experience in design and build through projects, research, labs, or internships.

* Proficiency with engineering tools (e.g., CAD, analysis software, lab instrumentation). Desired Skills and Qualifications * MS in Mechanical Engineering, Aerospace Engineering, or related discipline (completed or in progress). * Prior internship, co-op, or project-based experience related to fluid systems, mechanisms, or structures.

* Ability to independently solve complex engineering tasks and seek out resources proactively.

* Comfortable working in a fast-paced, startup environment with a collaborative, mission-driven mindset.

* Excitement for Radiant's mission to rapidly deploy nuclear microreactors to remote locations requiring abundant, clean energy.

* Knowledge of reactor physics is helpful but not required.

Additional Requirements * This role is based onsite at Radiant's HQ in El Segundo, CA.

* Extended hours or occasional weekend work may be required to support project milestones.