Staff/Principal 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.

Staff/Principal Software Engineer - Tools & Infrastructure

About The Role

Radiant is seeking a Lead Software Engineer for Internal Tools & Infrastructure to develop the software infrastructure, developer tooling, and data processing capabilities that power our engineering organization in simulation, multi-physics modeling and analysis, high-performance computing, and scientific computing. 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.

Responsibilities and Duties

- Hands-on development of internal platforms that provide real-time monitoring, Digital Twin visualizations, simulation post-processing, and analysis tools for Kaleidos reactor systems.

- Develop our HPC infrastructure, environment and tooling necessary to maintain high-quality standards and detect issues in real time across engineering systems.

- Design and implement integration platforms that enable seamless data flow across Radiant's engineering ecosystem, using connectors and APIs to bridge CAD systems, Multiphysics simulation tools, data acquisition systems, and engineering databases.

- 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.

- Design and build internal developer tooling, scientific tooling, including CI/CD pipelines, version control systems, artifact management, build systems, developer environments, testing frameworks, and release processes.

Required Qualifications

- Bachelor's degree in computer science, physics, mechanical engineering, or a related engineering field.

- 6+ years of professional software engineering experience with deep expertise in developer productivity, software tooling, infrastructure, high-performance computing (HPC), 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.

- Experience integrating software solutions into hardware systems such as robotics, controls, circuits, devices, 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 for automated build and deployment pipelines.

Preferred Qualifications

- Advanced degree (Master's and or PhD) in computer science, physics, mechanical, electrical engineering, or a similar field.

- 8+ years of professional software engineering experience with deep expertise in developer productivity, software tooling, infrastructure, high-performance computing (HPC), or platform engineering.

- 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 record in architecting distributed systems, databases, large-scale data systems, and high-performance backend APIs.

- Experience with observability and monitoring systems using Datadog, Grafana, Prometheus, InfluxDB, or similar tools.

- Familiarity with TypeScript, React, Angular, Vite, Node.js, and other modern web frameworks.

- Track record in building developer platforms or infrastructure-as-a-service systems.

- Previous experience working in an embedded SWE role is a plus.

Work Environment

- Must work 100% onsite at El Segundo HQ.

- Must be willing to work extended hours and weekends as necessary to accomplish our mission.

Total Compensation And Benefits

Radiant compensates people for impact and invests in those who continue to raise the bar. Radiant’s new hire compensation package includes base salary, substantial equity grants, and comprehensive health benefits. Total compensation and level are determined through a rigorous evaluation of interview performance, experience, education, and qualifications, and are designed to support continued growth as scope, responsibility, and impact expand at Radiant.

The best of today’s advanced reactor builders don’t wait for job postings. They join the winning team. If that’s you, contact us directly for immediate opportunities: recruiting@radiantnuclear.com.

Benefits And Perks For Eligible Employees

- Stock: Substantial incentive stock plan for all full-time employees. - Medical: 100% premium coverage for base Silver level plan for employee + 50% premium coverage for dependents. Platinum plans available.

- One Medical: Sponsored memberships for eligible employees and their dependents.

- Vision: 100% premium coverage for top tier plan + 50% for dependents. - Dental: 100% premium coverage for top tier plan (including orthodontia) + 50% for dependents.

- Voluntary life, accident, hospital, critical illness, commuter and FSA/HSA are offered as employee contributed benefits.

- 8-weeks of paid parental leave for all parents. Additional paid pregnancy leave for CA employees.

- Daily catered lunch. Free snacks and drinks.

- Flexible PTO policy. Remote workday allocation.

- Company and team-bonding events, happy hours and in-person camaraderie.

- Beautiful El Segundo headquarters close to the Pacific Ocean.

- Burgeoning satellite offices in Oak Ridge, TN and Washington, D.C., near Capitol Hill.

We are an equal opportunity employer and all qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity or expression, pregnancy, age, national origin, disability status, genetic information, protected veteran status, or any other characteristic protected by law.

Unfortunately, we are unable to provide visa sponsorship at this time. This position involves access to technology that is subject to U.S. export controls. Any job offer made will be contingent upon the applicant’s capacity to serve in compliance with U.S. export controls.