Principal Software Engineer, Compute

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.

Radiant is seeking a driven Principal Dev Ops Engineer to own on‑site High‑Performance Compute (HPC) infrastructure, deployment, 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 Dev Ops 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 workflows, tools, and optimizations.

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 design, run, and mass‑produce the first high‑temperature gas‑cooled portable microreactor ever commercialized.

• Lead HPC initiatives as driven by the software org, establishing responsibilities, project scope, and technical mentorship.
• Serve as the go‑between for engineering teams and software, fielding HPC questions, simulation software issues, and infrastructure needs from nuclear, thermal, materials, mechanical, and electrical engineers, translating them into actionable work.
• Own workflows, tooling, and performance for scientific computing, including Ansys, STAR‑CCM+, and Abaqus, covering licensing, environment setup, job orchestration, and results infrastructure.
• Triage inbound infrastructure requests, HPC/MPI/Linux debugging, job failure analysis, shell and systems mentorship, while prioritizing effectively and communicating clearly across stakeholders.
• Partner with Dev Ops engineers to architect and maintain infrastructure across AWS and on‑premises Linux environments, ensuring high availability, security, and performance for mission‑critical systems.
• Dive deep into HPC software, workload scheduling, data movement, storage hierarchies, and compute environments to build robust, high‑throughput Linux systems.
• Modernize legacy scientific computing systems and tooling, migrating to current stacks to improve maintainability, performance, and developer experience.
• Architect tools supporting build systems, testing frameworks, deployment automation, and developer environments.
• Design and maintain networking infrastructure for distributed simulation systems, optimizing data transfer between HPC clusters.

• Bachelor’s degree in Computer Science, Engineering, or a related technical field.
• 8+ years of professional experience in Dev Ops, Site Reliability, Infrastructure, or Platform Engineering.
• Expert‑level proficiency in one or more languages:
  Python, Golang, Rust, C#, or C/C++.
• Strong code review skills, including the ability to read stack traces and chase down dense rabbit holes in high‑compliance, legacy scientific software environments.
• Working experience with Kubernetes and Docker for orchestration and deployment.
• Deep Linux and sysadmin fluency, file systems, process management, and networking, with a hard‑science approach to problem‑solving.
• Exceptional communication skills,…