Software Engineer (Hardware-in-the-Loop)

About Radiant 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, fail-safe microreactor that can be transported anywhere power is needed and run for up to 5 years without refueling. 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 leverages modern software engineering to rapidly deliver safe, factory-built microreactors that use existing, well-qualified materials. Founded in 2020, Radiant is on track to test its first reactor at the Idaho National Laboratory this summer, with initial customer deliveries beginning in 2028. About the Role Radiant is seeking a Hardware-in-the-Loop (HiL) Engineer to develop Radiant’s HiL systems for current and future products. In this role, you will be responsible for end-to-end development, including defining system requirements; supporting hardware sourcing and development; developing the software architecture; developing and maintaining the HiL software; developing and maintaining test automation; and supporting integration testing. This role is ideal for candidates comfortable working both autonomously and with an interdisciplinary team, as well as in early design architecture phases of development. You will have the opportunity to build electrical integration systems from the ground up that will drive success towards the first high-temperature gas-cooled portable microreactor ever to be commercialized. Responsibilities and Duties: Design, develop, and maintain hardware-in-the-loop (HIL) test bench systems. Develop and maintain the HiL systems plant software. Support building and configuring test hardware, including power supplies, actuator modeling, and sensor mapping. Support integrating the HiL software with physics simulation models, including thermal, neutronics, and power generation simulation models. Own schedule and vendor management for the HIL systems. Own communication and integration between hardware, control systems, and software interfaces. Drive optimization of test and validation processes and lead improvements in tooling and automation. Support the planning, development, and execution of integration tests. Lead design reviews and communicate technical decisions to cross-functional stakeholders. Required Skills and Qualifications: BS in Electrical Engineering, Computer Engineering, Mechanical Engineering, Computer Science, or a related field. 3+ years developing hardware-in-the-loop systems. Proficient in designing, implementing, and debugging software within HIL frameworks (dSPACE, Speedgoat, etc.). Hands-on experience with automated test case development and generating comprehensive test reports. Experience in MATLAB or Python for data processing, analysis, and visualization. Skilled in electrical debugging and root cause analysis. Desired Skills and Qualifications: Practical knowledge of the fundamental concepts of controls, software testing, and test processes. Hands-on skills to design, build, bring up, and debug test benches. Experience with real-time simulation systems and FPGA-based hardware. Strong understanding of control fundamentals and software testing processes. Experience with trace capture tools or data acquisition and analysis tools. Background in high-reliability, safety-critical, or regulated industry environments (aerospace, defense, nuclear, medical, or automotive). 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. Benefits and Perks 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. 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 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: recruiting@radiantnuclear.com . 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.