About Radiant

Radiant is an El Segundo, CA-based company building the world's only mass-produced, transportable nuclear microreactors. The U.S. grid is under growing strain, with power demand accelerating, driving higher utility costs, rising carbon emissions, and interconnection backlogs. Radiant has a solution, transportable, on-site power. Our first reactor, Kaleidos, is 1 megawatt: small enough to be factory-built, transported by land, sea, or air, and deployed wherever power is needed. 1 MW can power 1000 homes for five years. Ship it back and we refuel for a 20 year operating life. We made energy a product that can be used for critical infrastructure like military bases, data centers, hospitals, and remote sites, as well as the commercial main street businesses that keep America running. Founded in 2020, Radiant is under contract to deliver power to the U.S. Army, Navy and Air Force and has signed pre-order agreements with Equinix, with deployments beginning in 2028.

About the Role

Radiant is seeking a highly motivated Senior Build Engineer to lead the assembly, integration, and build execution of high-performance turbomachinery systems for our portable nuclear microreactor. This is a hands-on engineering role requiring strong mechanical fundamentals, precision assembly experience, and the ability to independently solve complex hardware challenges.

You will take ownership of prototype and first-article turbomachinery builds, working closely with design, manufacturing, and test teams to translate engineering designs into functional, test-ready hardware. This role will be instrumental in developing assembly processes, resolving integration challenges, and improving hardware reliability and build repeatability as we advance toward production.

Responsibilities & Duties

Turbomachinery Build & Integration

Lead hands-on assembly, integration, and troubleshooting of complex turbomachinery hardware, including compressors, turbines, rotors, electric motors, bearings, seals, and housings.

Own precision assembly operations, including rotor stacking, bearing installation, balancing, alignment, and mechanical fit-up.

Interpret engineering drawings, GD&T, tolerance stack-ups, and mechanical specifications to ensure proper assembly and hardware functionality.

Identify and resolve assembly challenges involving tight tolerances, component interfaces, alignment, and mechanical interference.

Drive first-article build execution, ensuring hardware meets engineering requirements and is ready for testing and validation.

Build Process Development & Tooling

Develop, implement, and refine assembly processes, work instructions, alignment procedures, and torque specifications for complex rotating machinery.

Design and develop custom assembly tooling, fixtures, and work-holding solutions to improve build efficiency, precision, and repeatability.

Evaluate assembly methods, identify process improvements, and establish best practices for transitioning prototype builds toward repeatable production processes.

Maintain detailed build documentation, including as-built configurations, inspection results, nonconformances, and lessons learned.

Technical Problem-Solving & Cross-Functional Collaboration

Partner closely with design, manufacturing, and test engineers to resolve hardware integration challenges and improve design for manufacturability and assembly.

Lead root cause investigations and corrective actions for assembly defects, mechanical failures, and hardware nonconformances.

Provide technical feedback on component design, tolerances, material selection, and assembly interfaces to improve hardware performance and reliability.

Support hardware testing, including pre-test inspections, post-test teardown, failure investigations, and implementation of design or process improvements.

Provide technical guidance and mentorship to junior engineers and technicians, establishing high standards for precision assembly, workmanship, and build quality.

Required Qualifications & Skills

Bachelor's degree in Mechanical Engineering, Aerospace Engineering, or a related engineering discipline.