Materials Engineer, Moderator Materials
Confirmed on the employer's own hiring board on Oct 22, 2026. First seen by Alion on Oct 20, 2026. Radiant Nuclear scores B on the Alion truth index.
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 Materials Engineer to own development, testing, and qualification of in-core moderator and reflector materials and related manufacturing processes used for the Kaleidos 1MW nuclear microreactor. The ideal candidate takes great ownership of their work end-to-end, is proficient in materials selection, testing, and analysis, and is excited to work in a highly cross-functional, fast-paced environment. You will be a key contributor to building the world's first mass-produced, rapidly-deployable nuclear reactor.
Responsibilities & Duties
Plan and execute materials testing to obtain material properties to inform design decisions.
Develop and qualify application-specific manufacturing processes such as graphitization, hot isostatic pressing, extrusion, etc.
Provide expert guidance in materials selection for moderator and reflector components within Kaleidos.
Lead R&D efforts for advanced moderator and reflector materials.
Develop and execute test campaigns to qualify moderator and reflector materials using in-house materials testing and characterization equipment as well as coordination with outside labs and vendors.
Evaluate data quality and accuracy of material property data for use in company materials database.
Define or improve manufacturing processes of components to achieve desired material properties.
Required Qualifications & Skills
Bachelor’s degree from an accredited institution in Materials Science and Engineering, or in Mechanical, Aeronautical, Nuclear, or Chemical Engineering with a materials science and engineering focus.
2+ years of experience working in the development, testing, and/or analysis of materials for demanding load cases and environments
Hands-on experimental or testing experience in laboratory or production environments
Desired Qualifications & Skills
Master’s or PhD degree from an accredited institution in Materials Science and Engineering, or in Mechanical, Aeronautical, Nuclear, or Chemical Engineering with a materials science and engineering focus.
Experience with development and qualification of nuclear moderator and reflector materials for high temperature and irradiation environments.
Knowledge of standard test methods for materials and experience with development of design allowables.
Self-motivated with strong organizational, written, and oral communication skills.
Demonstrated ability to work collaboratively with design and operations teams to deliver high-value results.
Experience with using text-based software development tools (Python or similar).
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: [email protected].
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.
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.