Principal Software Engineer, HPC DevOps

About the role

Radiant, an El Segundo‑based startup developing portable nuclear microreactors, is looking for a Principal Software Engineer to lead developer productivity, high‑performance compute (HPC) infrastructure and scientific computing workflows. The role will own the on‑site HPC environment that supports engineers across nuclear, thermal, materials, mechanical and electrical disciplines.

Key responsibilities

• Design, build and maintain on‑premises HPC infrastructure and scientific computing environments.
• Own workflows, tooling and performance for applications such as Ansys, STAR‑CCM+ and Abaqus, including licensing, environment setup, job orchestration and results handling.
• Act as the primary liaison between engineering and software teams, translating HPC, simulation and infrastructure requests into actionable work.
• Triage infrastructure requests, debug MPI/Linux issues, analyse job failures and provide mentorship on shell and system usage.
• Modernize legacy scientific computing stacks, migrating to current tools to improve maintainability and performance.
• Collaborate with DevOps engineers to architect and operate systems on AWS and on‑premises Linux, ensuring high availability, security and performance for mission‑critical workloads.

Required profile

• Extensive experience with HPC environments, Linux system administration and MPI debugging.
• Proven ability to manage cross‑disciplinary technical requests and prioritize work effectively.
• Strong organizational skills and patience for working with complex legacy stacks.
• Technical leadership experience, defining team scope and responsibilities.

Required skills

• Ansys
• STAR‑CCM+
• Abaqus
• MPI
• Linux
• AWS