Staff Fluid 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 highly motivated Staff Fluid Systems Engineer to own critical Kaleidos fluid systems from preliminary design through build and production. These systems include the primary loop subsystems and power conversion loop, serving to convert heat from the reactor core into electrical power. You will be responsible for the following: trade studies, component selection, thermal hydraulic analysis, piping design, vendor selection, assembly, and testing. You will have an instrumental impact of fueling the first new commercial reactor design in over 50 years by 2026.

Responsibilities

• Own end-to-end engineering of fluid systems and components, including compressors, valves, and heat exchangers.
• Perform complex thermal and fluids analysis to drive design decisions, verify system performance, and ensure structural integrity using first-principle hand calculations and finite element tools.
• Perform trade studies to optimize system and meet program requirements.
• Develop and execute manufacturing/assembly instructions and test plans.
• Create and manage a Bill-Of-Materials (BOM).
• Find and develop suppliers for all components.
• Own subassembly design, manufacturing, and test schedules.
• Own risk analysis (FMEA) for subsystems.
• Collect requirements, provide expertise and feedback to engineers in other functional areas via clear, constructive