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Radiant is building the world's first mass-produced, portable nuclear microreactors. The Kaleidos reactor is a 1-megawatt, fail-safe microreactor designed for rapid deployment to hospitals, data centers, remote sites, and military bases, capable of running for up to 5 years without refueling. Founded in 2020, Radiant is preparing for its first reactor test at Idaho National Laboratory this summer, with customer deliveries beginning in 2028.
As a Hardware-in-the-Loop (HIL) Engineer, you will own end-to-end development of Radiant's HIL test systems for current and future products. This is a hands-on role spanning system requirements definition, hardware sourcing support, software architecture design, test automation development, and integration testing. You will work autonomously and collaboratively with an interdisciplinary team during early design phases, building electrical integration systems that will validate the first high-temperature gas-cooled portable microreactor to reach commercialization.
Key responsibilities include designing and maintaining HIL test benches; developing and maintaining HIL plant software; configuring test hardware including power supplies, actuator modeling, and sensor mapping; integrating HIL software with physics simulation models (thermal, neutronics, power generation); managing schedules and vendors for HIL systems; owning communication between hardware, control systems, and software interfaces; optimizing test and validation processes; supporting integration test planning and execution; and leading design reviews with cross-functional stakeholders.
Required qualifications: BS in Electrical Engineering, Computer Engineering, Mechanical Engineering, Computer Science, or related field; 3+ years developing hardware-in-the-loop systems; proficiency in HIL frameworks (dSPACE, Speedgoat, etc.); hands-on experience with automated test case development and test reporting; MATLAB or Python for data processing and visualization; skilled electrical debugging and root cause analysis.
Desired qualifications include knowledge of controls, software testing, and test processes; hands-on test bench design and debug skills; real-time simulation and FPGA experience; control fundamentals understanding; trace capture or data acquisition tools experience; background in high-reliability, safety-critical, or regulated industries (aerospace, defense, nuclear, medical, automotive).
The role requires 100% onsite work at El Segundo headquarters and willingness to work extended hours and weekends as needed. Radiant offers substantial equity, comprehensive health benefits (medical, vision, dental), 8 weeks paid parental leave, daily catered lunch, flexible PTO, and team bonding events.
