Job Description

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.

Internship Summer 2026 - Materials Engineer

Radiant is seeking a highly motivated Materials Engineer Intern to own development, testing, and qualification of materials and related manufacturing processes used in 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.


Please note: we plan to begin interviewing for Summer 2026 internships in November/December.


Responsibilities & Duties

• Plan and execute materials testing to obtain material properties to inform design decisions.
• Develop and qualify application-specific manufacturing processes related to metals, ceramics, composites, or polymers.
• Provide expert guidance in materials selection for components within Kaleidos.
• Identify, procure, and operate equipment for materials characterization and testing.
• 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

• Enrolled in Bachelor's degree from an accredited institution in Materials Science and Engineering, or in Mechanical, Aeronautical, Nuclear, or Welding Engineering with a materials science and engineering focus.
• Experience working in the development, testing, and/or analysis of materials for demanding load cases and environments from projects, laboratory work, research, internships, or prior work experience
• Hands-on experimental or testing experience in laboratory or production environments

Desired Qualifications & Skills

• Enrolled in a Master's or PhD degree from an accredited institution in Materials Science and Engineering, or in Mechanical, Aeronautical, Nuclear, or Welding Engineering with a materials science and engineering focus.
• Experience with development and qualification of solid-state processing of materials.
• 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:

• This internship will require working onsite at our El Segundo HQ.
• You may be asked to work extended hours or weekends occasionally to support project goals.

Total Compensation and Benefits

Radiant's new hire compensation package includes base salary, substantial equity grants, and comprehensive benefits. Total compensation and level are determined through a holistic evaluation of your interview performance, experience, education, and qualifications.


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.

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.

Job Tags

Full time, Work experience placement, Summer work, Summer internship, Remote work, Flexible hours, Weekend work,

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