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Job Summary:
Radiant is a startup based in El Segundo, CA, focused on building portable nuclear microreactors. The Principal Software Engineer will oversee High-Performance Compute infrastructure and collaborate with scientists and engineers to design scalable computing practices and tools.
Responsibilities:
• Lead HPC initiatives as driven by the software org, establishing responsibilities, project scope, and technical mentorship.
• Own workflows, tooling, and performance for scientific computing, including Ansys, STAR-CCM+, and Abaqus, covering licensing, environment setup, job orchestration, and results infrastructure.
• Dive deep into HPC software, workload scheduling, data movement, storage hierarchies, and compute environments to build robust, high-throughput Linux systems.
• 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.
• Triage inbound infrastructure requests, HPC/MPI/Linux debugging, job failure analysis, and shell and systems mentorship, while prioritizing effectively and communicating clearly across stakeholders.
• Modernize legacy scientific computing systems and tooling, migrating to current stacks to improve maintainability, performance, and developer experience.
• Design and maintain networking infrastructure for distributed simulation systems, optimizing data transfer between HPC clusters.
• Partner with DevOps engineers to architect and maintain systems across AWS and on-premises Linux environments, ensuring high availability, security, and performance for mission-critical workloads.
• Architect tools supporting build systems, testing frameworks, deployment automation, and developer environments.
Qualifications:
Required:
• Bachelor's degree in Computer Science, Engineering, Physics or a related technical field.
• 8+ years of professional experience in HPC, scientific computing, infrastructure, or platform engineering.
• Deep Linux and sysadmin fluency, file systems, process management, and networking, with a hard-science approach to problem-solving.
• Hands-on experience with HPC environments, simulation workloads, or academic/research computing (SLURM, PBS, MPI, Lustre, EFS, AWS ParallelCluster, or similar).
• Strong 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.
• Exceptional communication skills; organized and effective when fielding a high volume of questions and requests from engineering stakeholders.
• Ability to dive deep into complex, nested legacy stacks and then zoom out to synthesize findings clearly for a broader technical audience.
Preferred:
• Master's degree or higher in Computer Science, Engineering, Physics, or a related technical field.
• Hands-on physical infrastructure experience: server hardware, rack configuration, data center ops, or high-throughput networking (InfiniBand, Slingshot, AWS EFA).
• Experience working cross-functionally with engineering teams across mechanical, electrical, materials, and nuclear disciplines.
• Working experience with Kubernetes and Docker for orchestration and deployment.
• Cloud infrastructure experience with Ansible, Terraform, or AWS in a cloud-native or hybrid environment.
• Experience with adjacent HPC domains, AI/ML training infrastructure, edge computing, quantum computing, visual computing (render farms), or big data analytics, where distributed hardware, GPU acceleration, and large-scale compute requirements overlap with traditional HPC environments.
• Comfortable picking up frontend work when needed, React or general JavaScript experience is a plus; an open mind toward full-stack contributions is more important than depth here.
Company:
Radiant develops portable nuclear microreactors designed to generate electricity and heat in a compact, factory-built form. Founded in 2019, the company is headquartered in El Segundo, USA, with a team of 51-200 employees. The company is currently Growth Stage.