Senior Software Engineer, Developer Productivity

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 Senior Software Engineer to support developer productivity, compute infrastructure, and scientific computing workflows. You'll help build and maintain the on-site HPC infrastructure and scientific computing environments that hard-science users depend on daily, working closely with the software team to build scalable, resilient tooling that lets engineers focus on their science, not their infrastructure.

You'll serve as a go-to resource for engineering teams navigating HPC and scientific computing questions, and grow into ownership of specific systems and tooling areas. The ideal candidate is patient and organized, comfortable managing a steady volume of cross-disciplinary requests, and capable of digging into complex legacy stacks to find and fix root causes. The infrastructure and tooling you build will help design, run, and mass-produce the first high-temperature gas-cooled portable microreactor ever to be commercialized.

• Support workflows, tooling, and performance for scientific computing, including Ansys, STAR-CCM+, and Abaqus, covering licensing, environment setup, job orchestration, and results infrastructure.

• Serve as a resource for engineering teams, fielding HPC questions, software issues, and infrastructure needs from nuclear, thermal, materials, mechanical, and electrical engineers, and translating them into actionable work.

• Triage inbound infrastructure requests, HPC/MPI/Linux debugging, and job failure analysis, prioritizing effectively and communicating clearly across stakeholders.

• Help modernize legacy scientific computing systems and tooling, migrating to current stacks to improve maintainability, performance, and developer experience.

• Partner with DevOps engineers to maintain systems across AWS and on-premises Linux environments, supporting high availability, security, and performance for mission-critical workloads.

• Contribute to tools supporting build systems, testing frameworks, deployment automation, and developer environments.

• Bachelor's degree in Computer Science, Engineering, Physics, or a related technical field.

• 4+ years of professional experience in developer productivity, site reliability, DevOps, infrastructure, or platform engineering.

• Linux and sysadmin fluency, file systems, process management, and networking.

• Strong proficiency in one or more languages: Python, Golang, Rust, C#, or C/C++.

• Solid code review skills, including the ability to read stack traces and work through legacy scientific software environments.

• Strong communication skills; organized and effective when fielding requests from engineering stakeholders.

• Ability to dig into complex, nested legacy stacks and communicate findings clearly to a broader technical audience.

• Master's degree 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.

• Hands-on experience with HPC environments, simulation workloads, or academic/research computing (SLURM, PBS, MPI, Lustre, EFS, AWS ParallelCluster, or similar).

• 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.

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

• Must work 100% onsite at El Segundo HQ.

• Stock: Substantial incentive stock plan for all full-time employees.

• Medical: 100% up to base silver level plan for employee + 50% dependents, offers up to Platinum plans.

• One Medical: Sponsored memberships for employees and their dependents.

• Vision: 100% top tier plan coverage + 50% for dependents.

• Dental: 100% top tier plan coverage, orthodontia extra, 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.

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: [email protected].
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.

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.