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 Engineering to own the strategy, execution, and team leadership for testing Kaleidos hardware and systems. This is a hands-on technical leadership role: you will directly manage a team of test engineers and serve as the technical owner for multi-discipline testing across the program. This is not limited to thermal, materials, structural, mechanical, and special-process testing.

You will lead test development across our product and build our test site from the ground up. This infrastructure will support rapid design iteration in development, evaluating thermal performance, material behavior, structural and mechanical response, leak integrity, and system reliability, and then transition into architecting acceptance testing for production units. You will work closely with design, analysis, materials, manufacturing, quality, supply chain, and operations teams to ensure designs are validated, robust, and production-ready.

Responsibilities & Duties

Test Hardware & Infrastructure Development

Lead requirements definition, design, and implementation of Radiant’s test hardware, including test rigs, fixtures, instrumentation, data acquisition, controls, and support systems for components, subsystems, and integrated systems.

Build, commission, calibrate, and maintain test capabilities across thermal, materials, mechanical, structural, and leak/flow disciplines.

Establish operating procedures, safety controls, and facility readiness for high-energy, high-temperature, vacuum, pressurized, and hazardous-materials environments.

Define equipment specifications, manage vendor selection and procurement, and plan test space layout.

Work with quality to manage calibration programs, measurement traceability, and uncertainty analysis for all test equipment.

Test Strategy, Planning & Technical Ownership

Own and lead the test strategy across development, qualification, and production acceptance phases.

Define test objectives, plans, success criteria, instrumentation strategies, and data requirements for hardware and systems.

Serve as the technical authority for test methods, measurement quality, and data integrity.

Translate analytical predictions and design requirements into targeted test campaigns that validate 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 functional, performance, environmental, transient, off-nominal, and endurance testing.

Operate test hardware hands-on with a strong emphasis on repeatability, data quality, and safety.

Analyze test data to assess system performance, thermal and mechanical behavior, and reliability.

Compare test results against analytical predictions and work with design teams to resolve discrepancies.

Collaborate with engineers to conduct root cause investigations, identify anomalies or failures, and implement corrective actions supported by test evidence.