Lead Test Engineer, Power Generation

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.

Radiant is seeking a Lead Test Engineer, Power Generation to own the strategy, execution, and team leadership for testing the power generation system including turbo machinery, 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 turbo machinery designs are validated, robust, and production‑ready.

• Lead requirements definition, design, and implementation of Radiant’s test site
• Design, build, commission, and maintain test rigs, fixtures, instrumentation, and support systems for turbo machinery, 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

• Own and lead the turbo machinery 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

• 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

• 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 turbo machinery 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…