Lead Nuclear Materials Engineer
Confirmed on the employer's own hiring board on Oct 13, 2026. First seen by Alion on Oct 12, 2026. Radiant Nuclear scores A 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.
Lead Nuclear Materials Engineer
Radiant is seeking a highly motivated Lead Nuclear Materials Engineer to lead Radiant’s nuclear materials team in the development, testing, and qualification of materials and related manufacturing processes used in the Kaleidos 1MWe nuclear microreactor. The ideal candidate is excited to grow an in-house nuclear materials team, is proficient in materials selection, testing, and analysis, takes great ownership of their work end-to-end, and thrives in a highly cross-functional, fast-paced environment. Your team’s ownership spans fuel, moderators, shielding, neutron poisons, and irradiation testing. You will be a key contributor to building the world's first mass-produced, rapidly-deployable nuclear reactor.
Responsibilities & Duties
Set the technical direction for the nuclear materials team, including the definition of project scopes, the guidance of day-to-day engineering and support activities, and the development of a nuclear materials roadmap to support future reactor designs and builds
Deliver materials solutions for fuel, moderator, shielding, and neutron poison designs for Kaleidos
Accountable for nuclear materials engineering team’s technical output
Lead and mentor team members technically and professionally
Communicate project status, issues, and schedules to teammates and executives
Present to external stakeholders and regulatory bodies (DOE, NRC)
Review test plans, purchase orders, and analysis
Provide surge materials engineering support as-needed
Manage irradiation testing from design of experiment through irradiation to post irradiation examination (PIE)
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.
5+ years of experience working in the development, testing, and/or analysis of nuclear 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.
2+ years of engineering leadership and management experience at a company building and/or testing hardware for nuclear, aerospace, or other extreme environments
Expert-level competency in at least one area of nuclear materials such as fuel, neutron poisons, shielding, or moderators
Experience with development and qualification of material systems for use in 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).
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: [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.