Senior System Administrator

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.

Senior System Administrator

Radiant is seeking a Senior System Administrator to join our growing team. In this role, you’ll help build and maintain the core infrastructure that supports the development, testing, and operation of our microreactor systems. You'll be a key technical contributor, ensuring our systems are secure, scalable, and reliable. You will have an opportunity to work in an interdisciplinary environment, with a high degree of ownership and drive, to advance milestones toward the commercialization of the first mass-produced nuclear reactor.

Responsibilities And Duties

- Design, deploy, and maintain Radiant’s server, storage, and network infrastructure (including hybrid cloud and on-prem environments).

- Establish specifications and standards for cloud and on-premises systems; create system documentation, architecture diagrams, and deployment guides; manage system migrations and technical onboarding, including account setup and required training.

- Deploy and manage hardware infrastructure across multiple sites; monitor and troubleshoot server performance using automation tools (PowerShell, Python, Terraform); implement security measures and continuous auditing.

- Ensure high availability, performance, and disaster recovery for critical systems and services.

- Implement and maintain system security, including patching, access control, hardening, and vulnerability management.

- Troubleshoot and resolve infrastructure incidents, performing root cause analysis and corrective action

- Collaborate with mechanical and production teams to install and configure PLCs, DAQs, and set up operator stations.

- Work with DevOps and other engineers to familiarize with software best practices in CI/CD deployment, Kubernetes orchestration, Docker containerization, monitoring, observability, automation, and more.

- Mentor junior team members and contribute to the development of infrastructure best practices across the organization.

Required Qualifications And Skills

- Bachelor’s degree in computer science, information technology, engineering, or a related field.

- 5+ years of professional experience as a system administrator or infrastructure engineer

- Strong Windows and Linux system administration skills in production environments

- In-depth understanding of networking concepts (TCP/IP, routing, DNS, firewalls) and storage systems

- Proficiency in scripting or programming languages (e.g., Bash, Python, PowerShell, Power Automate) for automation.

- Experience with infrastructure as code tools (e.g., Terraform, Ansible, or similar)

- Experience with PLCs (like Beckhoff or Rockwell Automation)

Desired Qualifications And Skills

- Highly self-motivated with strong communication skills and a desire to grow and develop in this role.

- Working experience in monitoring and maintaining AWS cloud infrastructure.

- Proficiency with AWS tools such as CloudFormation, AWS CDK, AWS CLI, and others.

- Working experience with managing, configuring, and troubleshooting Kubernetes clusters in production environments.

- Experience in testing software and hardware systems

- Familiarity with real-time systems, embedded environments, or hardware/software integration

- Prior experience with administering Microsoft 365 or Google Workspace

- Prior work in regulated or high-assurance environments (e.g., nuclear, aerospace, defense, healthcare)

Additional Requirements

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

- Must work 100% onsite at El Segundo HQ.

Total Compensation And Benefits

Radiant's new hire compensation package includes base salary, substantial equity grants, and comprehensive benefits. Total compensation and level are determined through a holistic evaluation of your interview performance, experience, education, and qualifications.

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.

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.