Principal Software Engineer, Compute

About Radiant

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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

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Radiant is seeking a driven Principal Software Engineer to own on-site High-Performance Compute infrastructure, scientific computing environments, and automation projects in tight collaboration with hard-science users and cloud infrastructure engineers. You will work closely with the software team to design scalable, secure, and resilient compute practices, tools, and systems across the entire organization.

As a technical lead, you will define team scope, shape individual responsibilities, and serve as the primary liaison between engineering and software teams, acting as the subject-matter expert on HPC workflows, simulation tooling, and compute optimization. The ideal candidate is patient, organized, and comfortable managing high volumes of cross-disciplinary requests, capable of diving deep into complex legacy stacks and synthesizing findings. The infrastructure you manage, the pipelines you build, and the developer-productivity culture you establish will help you design, run, and mass-produce the first high-temperature gas-cooled portable mi...