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.
We are seeking a Build Engineer, Turbomachinery to help bring high-speed rotating hardware from design into reality. This is a hands-on role ideal for new graduates or early-career engineers who want to learn by building, assembling, and integrating complex turbomachinery systems. You will work closely with design, test, and manufacturing teams, helping prepare hardware for first-article testing and system validation.
This is a fantastic opportunity to gain real-world experience with high-speed, high-temperature rotating machinery while making a direct impact on a first-of-its-kind nuclear microreactor program.
Responsibilities
Hands-On Builds & Assembly
- Responsible for assembly and integration of prototype and first-article turbomachinery hardware, including compressors, turbines, rotors, electric motors, bearings, seals, and housings
- Develop precise assembly instructions, alignment procedures, and torque specifications
- Support rotor stacking, bearing installation, balancing, and alignment operations
- Document assembly activities, as-built observations, and lessons learned
Process & Tooling Support
- Help develop and maintain build tools, fixtures, and workholding solutions
- Support creation of work instructions and standard operating procedures for assembly processes
- Provide feedback to design and manufacturing teams to improve hardware assembly and integration
Cross-Functional Collaboration
- Work closely with design engineers, test engineers, and technicians to prepare hardware for testing and validation
- Participate in troubleshooting assembly issues and contribute to iterative improvements
- Receive mentorship from senior build engineers while gradually taking on more responsibility
Learning & Growth
- Gain experience with high-speed rotating machinery, tight tolerances, and precision assembly
- Learn industry best practices for turbomachinery build, integration, and first-article readiness
- Develop problem-solving skills and hands-on engineering judgment in a fast-paced startup environment
Required Qualifications
- Bachelor’s degree in Mechanical Engineering or a related field (or expected graduation within 6 months)
- Strong interest in hands-on mechanical assembly, rotating machinery, or turbomachinery systems
- Basic understanding of GD&T, fits, torque, and alignment principles
- Comfort reading and interpreting mechanical drawings and CAD models
- Willingness to learn, take initiative, and work safely with precision hardware
Desired Qualifications
- Prior hands-on experience from internships, co-ops, class projects, or design competitions (SAE, Formula SAE, robotics, etc.)
- Familiarity with mechanical assembly, rotor balancing, or bearing handling
- Interest in turbomachinery, power generation, or high-speed rotating systems
- Excited to work in a fast-paced, innovative startup environment
- Prior nuclear experience is not required
Additional Requirements
- Must be willing to work extended hours and occasional weekends to support build schedules
- Must work 100% onsite at Radiant’s El Segundo headquarters
This is an exempt salaried role.
Total Compensation and Benefits
Radiant compensates people for impact and invests in those who continue to raise the bar. Radiant’s new hire compensation package includes base salary, substantial equity grants, and comprehensive health benefits. Total compensation and level are determined through a rigorous evaluation of interview performance, experience, education, and qualifications, and are designed to support continued growth as scope, responsibility, and impact expand at Radiant.
The best of today’s advanced reactor builders don’t wait for job postings. They join the winning team. If that’s you, contact us directly for immediate opportunities: [email protected].
Benefits and Perks for Eligible Employees:
- Stock: Substantial incentive stock plan for all full-time employees.
- Medical: 100% premium coverage for base Silver level plan for employee + 50% premium coverage for dependents. Platinum plans available.
- One Medical: Sponsored memberships for eligible employees and their dependents.
- Vision: 100% premium coverage for top tier plan + 50% for dependents.
- Dental: 100% premium coverage for top tier plan (including orthodontia) + 50% for dependents.
- Voluntary life, accident, hospital, critical illness, commuter and FSA/HSA are offered as employee contributed benefits.
- 8-weeks of paid parental leave for all parents. Additional paid pregnancy leave for CA employees.
- Daily catered lunch. Free snacks and drinks.
- Flexible PTO policy. Remote workday allocation.
- Company and team-bonding events, happy hours and in-person camaraderie.
- Beautiful El Segundo headquarters close to the Pacific Ocean.
- Burgeoning satellite offices in Oak Ridge, TN and Washington, D.C., near Capitol Hill.
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.
Top Skills
What We Do
Radiant is a clean energy startup building a nuclear microreactor. A climate-friendly alternative to diesel generators, Radiant's Kaleidos 1MW microreactor will be the world's first portable, zero-emissions power source that works anywhere. We plan to test our development reactor by 2026 and if successful, it will be the first new commercial reactor design to achieve a fueled test in over 50 years. Our microreactor can bring power to remote parts of the world and provide backup power for life-saving applications in hospitals or disaster-relief scenarios.
Why Work With Us
Our world-class team has prior experience in complex hardware development from SpaceX, McMaster, The Boring Company, and renowned national laboratories that define our mentality to radically improve our microreactors. We care deeply about our mission to reduce carbon emissions, and have fun while doing so from trivia nights to ski retreats.
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