Senior Software Engineer - Tools and Infrastructure El Segundo, California,

Senior Software Engineer - Tools and Infrastructure

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 failsafe microreactor that can be transported anywhere power is needed and run for up to five years without the need to refuel. 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 utilizes modern software engineering to rapidly achieve safe, factory-built microreactors that leverage existing, well-qualified materials. Founded in 2020, Radiant is on track to test its first reactor next year at the Idaho National Laboratory, with initial customer deliveries beginning in 2028.

Radiant is seeking a Senior Software Engineer for Internal Tools & Infrastructure to develop the software infrastructure, developer tooling, and data processing capabilities that power our engineering organization. In this deeply technical role, you will design and implement platform systems that enable faster iteration on reactor designs, sophisticated Digital Twin simulation and visualization, and data-driven analysis across the company. You will work in a highly interdisciplinary environment to solve complex technical challenges that accelerate our path to deploying the world's first mass-produced nuclear reactor.

• Develop and implement core infrastructure systems for internal tools, compute platforms, CI/CD pipelines, and data processing at scale.
• Design and build internal developer tooling, including CI/CD pipelines, version control systems, artifact management, build systems, developer environments, testing frameworks, and release processes.
• Hands‑on development of full‑stack web applications that provide real‑time monitoring, Digital Twin visualizations, simulation post‑processing, and analysis tools for Kaleidos reactor systems.
• Build infrastructure and tooling necessary to maintain high‑quality standards and detect issues in real time across engineering systems.
• Collaborate on technical initiatives across software, simulation, electrical, mechanical, and nuclear teams.
• Work across teams to integrate software with hardware platforms, control systems, and external software tools.

• Bachelor's degree in computer science, physics, mechanical engineering, or a related engineering field.
• 5+ years of professional software engineering experience with deep expertise in developer productivity, software tooling, infrastructure, compute, or platform engineering.
• Expert-level proficiency in programming languages such as Python, Golang, Rust, C#, or C/C++.
• Deep understanding of system design, data structures, algorithms, and distributed systems architecture with a track record of designing systems from the ground up.
• Strong foundation in software engineering best practices, including version control, code review, testing, and CI/CD methodologies.
• Extensive hands‑on experience in distributed software development, building systems, and infrastructure automation.
• Expert-level knowledge of containerization (Docker), orchestration (Kubernetes), and infrastructure‑as‑code tools (Terraform, Ansible, etc.).
• Significant experience architecting and implementing systems in hybrid cloud/on‑premises environments, specifically AWS and Linux.
• Familiarity with Git version control, Docker containerization, and common CI/CD frameworks (ArgoCD, Git Hub Actions, Git Lab CI/CD, Jenkins, Circle
  
  CI, Azure Pipelines, or similar) for automated build and deployment pipelines.

• Experience in highly regulated industries (aerospace, defense, automotive, nuclear, or medical devices).
• Technical understanding of simulation workflows, computational modeling, or scientific computing infrastructure.
• Hands‑on experience with big data processing systems (Spark, Hadoop, Airflow, Trino, Kubernetes‑based platforms)
• Proven track…