About Radiant

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, fail-safe microreactor that can be transported anywhere power is needed and run for up to 5 years without refueling. 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 leverages modern software engineering to rapidly deliver safe, factory-built microreactors that use existing, well-qualified materials. Founded in 2020, Radiant is on track to test its first reactor at the Idaho National Laboratory this summer, with initial customer deliveries beginning in 2028.

About the Role

Radiant is seeking a highly motivated Senior Mechanical Engineer to join the team responsible for the power generation and primary cooling turbomachinery of our Kaleidos product. This role involves performing the rotordynamic analysis and bearing selection of high-speed rotating machinery including compressors, turbines, and pumps for high-temperature applications. The ideal candidate will have a strong background in rotordynamics and bearing selection, along with hands-on experience testing real hardware. 

Responsibilities & Duties:   

• Design, build, and test turbomachinery for Radiant’s power generation systems. 

• Perform dynamic analysis of rotor-bearing systems to evaluate vibrational behavior, stability, and resonance characteristics. 

• Conduct critical speed analysis, Campbell diagram analysis, and stability assessments to optimize rotor system design for minimal vibration and resonance. 

• Analyze rotor response under transient operating conditions, including startup, shutdown, and off-design operations. 

• Select appropriate bearing types (e.g., rolling element, fluid film, magnetic) based on operating conditions and performance requirements. Evaluate bearing loads, life, and thermal performance. 

• Prepare technical reports, design documentation, and presentation materials. 

• Support the build and testing of prototype, first article, and production hardware.

Required Qualifications & Skills:  

• Bachelor’s or Master’s degree in Mechanical Engineering or a related field. 

• 5+ years of experience in the design and analysis of turbomachinery, rotating equipment, or mechanisms. 

• Strong understanding of rotordynamic principles and tools (e.g., XLrotor, Dyrobes, or equivalent). 

• Excellent problem-solving, technical communication, and organizational skills.

Desired Qualifications & Skills:   

• Prior experience with power generation applications. 

• Knowledge of bearing selection for high-temperature, high-speed applications. 

• Hands-on experience with turbomachinery testing and instrumentation. 

• Familiarity with relevant industry standards (API, ASME, ISO). 

• Prior nuclear experience is not required for this role.   

Additional Requirements:

• Must be willing to work extended hours and weekends as necessary to accomplish our mission. 

• Must work 100% onsite at El Segundo HQ. 

Benefits and Perks

• Stock: Substantial incentive stock plan for all full-time employees.

• Medical: 100% up to base silver level plan for employee + 50% dependents, offers up to Platinum plans.

• One Medical: Sponsored memberships for employees and their dependents.

• Vision: 100% top tier plan coverage + 50% for dependents.

• Dental: 100% top tier plan coverage, orthodontia extra, 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.

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: recruiting@radiantnuclear.com.

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.