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.
Responsibilities & Duties
- Support the mechanical design and ownership of electrical components and subsystems, including:
- Mechanical design of electrical assemblies such as control panels, enclosures, brackets, mounts, and supports
- Cable and wiring harness routing, retention, strain relief, bend radius compliance, and serviceability considerations
- Packaging of sensors, actuators, connectors, and electrical hardware within constrained assemblies
- 3D CAD modeling and 2D drawing creation using Siemens NX, including tolerance stack-ups and GD&T basics
- Perform first-order load calculations (static, shock, vibration) to support structural design decisions
- Conduct thermal analysis and heat-transfer assessments for electrical components, enclosures, and assemblies
- Support selection of materials, fasteners, and finishes appropriate for electrical, thermal, and environmental requirements
- Assist in the design and setup of test fixtures and test stands for acceptance and qualification testing
- Participate in system integration, troubleshooting, and validation activities alongside electrical and systems engineers
- Collect and interpret technical requirements and provide clear, constructive feedback across mechanical, electrical, software, and systems disciplines
- Develop, document, and execute basic test plans and procedures to verify mechanical and thermal performance
- Perform trade studies and first-order analyses to evaluate design options and constraints
- Generate and maintain design documentation to support Design for Manufacturing (DFM), assembly, and serviceability
- Support subassembly design, coordinate with manufacturing, and assist with build and test schedules
Required Qualifications & Skills
- Bachelor’s degree in Mechanical Engineering or a closely related field from an accredited institution
- Hands-on experience with mechanical design through coursework, labs, internships, senior design projects, or engineering clubs
- Proficiency or coursework experience using Siemens NX or similar 3D CAD tools
- Familiarity with mechanical design of electrical assemblies, including enclosures, brackets, and harness routing principles
- Basic understanding of structural mechanics, load paths, and first-order stress calculations
- Introductory knowledge of thermal analysis, heat transfer, and thermal management concepts
- Ability to read and create mechanical drawings, including dimensions and tolerances
- Strong communication skills and ability to collaborate in a multidisciplinary engineering environment
- Must be willing to work extended hours and weekends as necessary to accomplish our mission
- Must work 100% onsite at El Segundo HQ
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.
Radiant Nuclear Compensation & Benefits Highlights
The following summarizes recurring compensation and benefits themes identified from responses generated by popular LLMs to common candidate questions about Radiant Nuclear and has not been reviewed or approved by Radiant Nuclear.
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Healthcare Strength — Employer materials emphasize fully covered employee medical on base plans, broad vision and dental coverage, and sponsored primary care memberships, which together lift perceived total compensation.
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Equity Value & Accessibility — Equity grants are described as substantial and available to all full‑time employees, providing company‑wide ownership opportunities.
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Wellbeing & Lifestyle Benefits — Day‑to‑day perks such as daily catered lunch, snacks, team events, and some remote‑workday allocation enhance the overall rewards package.
Radiant Nuclear Insights
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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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