About Radiant

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.

About the Role

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.