Principal Power Systems Engineer

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 talented Principal Power Systems Engineer to lead the design, modeling, and validation of electrical power systems supporting our nuclear microreactor platform. You will play a critical role in defining how power is generated, conditioned, controlled, and delivered to customers across grid-connected, islanded, and rapidly deployable environments. In this role, you will own power system studies from early architecture tradeoffs through detailed modeling, testing, and system validation. You’ll collaborate closely with electrical design, controls, turbomachinery, nuclear, thermal, and software teams to ensure safe, stable, and reliable power delivery under a wide range of operating and contingency conditions. This role is central to commercializing Earth’s first mass-produced portable nuclear reactors. Responsibilities & Duties: Own power system architectural design for microreactor-based power generation systems operating in grid-connected and islanded modes. Develop single-line diagrams of the power system for single- or multiple-reactor configurations. Develop FMEAs to identify system behavior during component/system failures and identify redundancy paths. Evaluate system behavior during disturbances such as load steps, faults, breaker operations, and loss-of-generation events. Size energy storage systems for reactor cold start and variable load demands. Own synchronization of multiple reactors in a microgrid and multiple reactors tied to grid. Collaborate cross-functionally with the power conversion team to understand generator requirements and design power systems that can integrate seamlessly. Participate in software-in-the-loop (SIL), hardware-in-the-loop (HIL), and system-level testing to validate/verify system performance. Support system checkouts, commissioning, and testing of all power requirements Regulatory compliance of power systems, including testing methods to verify power quality. Required Qualifications & Skills: B.S. in Electrical Engineering with an emphasis in power systems or control systems. 5+ years of experience designing power systems for generation, microgrids, or mission-critical power systems. Experience with sizing and integrating high-voltage battery systems with power electronics. Strong experience with power system modeling and simulation tools (e.g., PSCAD, ETAP, PSS®E, Simulink, or equivalent). Solid understanding of inverters, grid converters, DC/DC converters, rotating generation, and power system control modes (grid-forming, grid-following, droop control). Experience in analyzing system stability, protection behavior, and fault response in complex electrical systems. Ability to clearly communicate technical concepts and results to cross-functional teams. Desired Qualifications & Skills: M.S. in Electrical Engineering or related discipline. Experience in power electronics development for high-power, medium-voltage equipment, including transformers, switchgear, inverters, active rectifiers, DC/DC converters, and generator controls. Experience with islanded power systems supporting critical loads. Familiarity with interconnection requirements, grid codes, and relevant IEEE or utility standards. Experience in modeling dynamic loads and fast-changing electrical demand. Exposure to nuclear, aerospace, defense, or other highly regulated industries. Experience mentoring junior engineers or leading technical efforts on complex programs. Additional Requirements: Must be willing to work extended hours and weekends as necessary to accomplish our mission. Must work 100% onsite at Radiant’s 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. 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. #J-18808-Ljbffr Radiant