Lead Test Engineer
Radiant
Lead Test Engineer
Radiant
Portable nuclear microreactors replacing diesel generators
Radiant is an El Segundo, CA-based company building the world's only mass-produced, transportable nuclear microreactors. The U.S. grid is under growing strain, with power demand accelerating, driving higher utility costs, rising carbon emissions, and interconnection backlogs. Radiant has a solution, transportable, on-site power. Our first reactor, Kaleidos, is 1 megawatt: small enough to be factory-built, transported by land, sea, or air, and deployed wherever power is needed. 1 MW can power 1000 homes for five years. Ship it back and we refuel for a 20 year operating life. We made energy a product that can be used for critical infrastructure like military bases, data centers, hospitals, and remote sites, as well as the commercial main street businesses that keep America running. Founded in 2020, Radiant is under contract to deliver power to the U.S. Army, Navy and Air Force and has signed pre-order agreements with Equinix, with deployments beginning in 2028.
Radiant is seeking a Lead Test Engineer, Power Generation to own the strategy, execution, and team leadership for testing the power generation system including turbomachinery, heat exchangers, controls, and primary cooling systems. This role is ideal for a hands-on technical leader who enjoys building test infrastructure, running complex hardware, and mentoring engineers and technicians while remaining deeply involved in day-to-day testing.
You will lead testing development for our high-speed machinery and own creating our test site from the ground up. This test infrastructure will be used to iterate quickly on our designs evaluating vibration, performance, thermal behavior, and system reliability in development and transition into acceptance testing for production units. This role works closely with mechanical design, analysis, manufacturing, and operations teams to ensure turbomachinery designs are validated, robust, and production-ready.
Responsibilities & Duties:
Test Site & Infrastructure Development
Lead requirements definition, design, and implementation of Radiant’s test site.
Design, build, commission, and maintain test rigs, fixtures, instrumentation, and support systems for turbomachinery, heat exchangers, controls, and primary cooling systems.
Establish operating procedures, safety controls, and facility readiness for high-speed, high-energy, and high-temperature test environments.
Test Strategy, Planning & Technical Ownership
Own and lead the turbomachinery test strategy across development, qualification, and production acceptance phases.
Define test objectives, plans, success criteria, instrumentation strategies, and data requirements for high-speed rotating machinery and supporting thermal-fluid systems.
Serve as the technical authority for vibration, rotordynamic, and bearing-related testing.
Translate analytical predictions (critical speeds, stability margins, transient response) into targeted test campaigns that validate design assumptions and retire risk.
Balance test coverage, technical risk, schedule, and hardware availability to enable rapid iteration while maintaining safety and rigor.
Test Execution & Data Analysis
Plan and execute development, qualification, and acceptance tests including startup/shutdown, transient, off-design, and endurance testing.
Operate test hardware hands-on with a strong emphasis on repeatability, data quality, and safety.
Analyze test data to assess vibration behavior, rotordynamic stability, bearing performance, thermal response, and overall system performance.
Compare test results against analytical predictions and work with design teams to resolve discrepancies.
Collaborate with mechanical engineers to conduct root cause investigations, identify anomalies or failures, and implement corrective actions supported by test evidence.
Technical Leadership & Team Development
Provide technical leadership and mentorship to test engineers and technicians.
Act as a player-coach: remain hands-on while scaling testing capability, throughput, and organizational maturity.
Support hiring, onboarding, and technical development of turbomachinery test personnel.
Develop work estimates, test schedules, and status updates for program leadership.
Review and approve test procedures, reports, and data packages.
Establish standards for test documentation, data management, and knowledge capture.
Help mature Radiant’s turbomachinery test processes, labs, and safety culture over time.
Cross-Functional Collaboration
Partner closely with turbomachinery mechanical engineers to ensure designs are testable and adequately validated.
Review component and system-level design documentation with an eye toward test coverage, instrumentation, and risk.
Collaborate with thermal, manufacturing, quality, and operations teams to support prototype, first-article, and production hardware testing.
Represent testing in design reviews, test readiness reviews, and technical leadership discussions.
Required Qualifications & Skills:
Bachelor’s or Master’s degree in Mechanical Engineering or a related field, or equivalent experience.
8+ years of experience in testing, development, or validation of turbomachinery, rotating equipment, or complex mechanical systems.
Hands-on experience testing high-speed rotating machinery and high-temperature hardware.
Experience correlating test results with analytical predictions and design intent.
Demonstrated technical leadership and ability to drive complex test efforts to completion.
Strong written, verbal, and organizational skills.
Desired Qualifications & Skills:
Prior experience leading or mentoring test engineers or technicians.
Experience with power generation or other high-reliability power generation systems.
Strong understanding of rotordynamics, vibration, and bearing behavior as applied to real hardware testing.
Familiarity with rotordynamic analysis tools (e.g., XLrotor, Dyrobes, or equivalent) from a test correlation or validation perspective.
Familiarity with relevant industry standards (API, ASME, ISO).
Startup or fast-paced hardware development experience.
Prior nuclear experience is not required.
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.
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.
Nuclear Engineering Certificate Program: 100% covered educational program with Penn State University, for eligible employees, to rapidly upscale into nuclear.
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 full-time 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.
Radiant designs and manufactures portable, factory-built nuclear microreactors for off-grid power. Its Kaleidos unit is a 1 MWe high-temperature gas-cooled reactor that uses TRISO fuel and a helium coolant, packaged in a container-sized module that can be transported by truck, ship, or air for rapid deployment to remote sites. The reactor runs for up to five years between refueling as part of a 20-year lifecycle and operates without water cooling, enabling flexible siting. Radiant differentiates itself through factory production of certified HTGR-based microreactors with an ambitious R-50 factory to enable mass production and fast deployment for energy resilience, military, data centers, and critical infrastructure. The company aims to provide reliable, emissions-free power that replaces diesel and supports resilient energy infrastructure at remote or critical locations.
Explore more opportunities at Radiant