Control Systems Test Engineer

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.

Control Systems Test Engineer

Radiant is seeking a highly motivated and detail-oriented Control Systems Test Engineer to join our team. In this role, you will be responsible for developing, maintaining, executing, and automating test cases across the full testing lifecycle for our reactor control systems. You will collaborate closely with systems engineers, controls developers, and software teams to ensure the highest quality and reliability in safety-critical control software.

Responsibilities & Duties

• Analyze and review control system Simulink models and associated design artifacts to understand system behavior and expected performance.


• Study and interpret system requirements for the reactor control system to develop comprehensive test coverage.


• Develop and maintain detailed test artifacts, including:
  
  
  
  • Unit test cases
  
  
  • Software-in-the-Loop (SiL) test cases
  
  
  • Hardware-in-the-Loop (HiL) test cases
  
  
  • Hardware test cases
  
  


• Execute all test cases across the testing spectrum:
  
  
  
  • Unit testing
  
  
  • SiL testing
  
  
  • HiL testing
  
  
  • Full hardware testing
  
  


• Automate testing workflows for SiL, HiL, and HW test cases using scripting languages such as Python or Go (Golang).


• Run and manage structured test campaigns, including regression suites.


• Execute and manage unit tests within the Simulink Test environment.


• Document all testing results clearly and concisely in test reports, including metrics, pass/fail criteria, and issues.


• Work collaboratively with developers and system engineers to identify root causes and support the resolution of defects.


• Contribute to continuous improvement of test processes, frameworks, and tools.

Required Qualifications & Skills

• Bachelor’s degree in Electrical Engineering, Computer Engineering, Mechanical Engineering, Controls Engineering, Computer Science, or related discipline.


• 2+ years of experience with Simulink/Matlab and working with dynamic system models.


• Strong understanding of software testing principles, including 2+ years of experience in unit, integration, SiL, HiL, and system testing.


• Proficiency in coding/scripting for test automation (e.g., Python, Golang, or similar).


• Hands-on experience with Simulink Test or equivalent test execution frameworks.


• Excellent analytical skills and attention to detail.


• Strong written and verbal communication skills.

Desired Qualifications & Skills

• Experience with safety-critical or regulated systems (e.g., aerospace, automotive, energy).


• Familiarity with version control systems (e.g., Git) and CI/CD pipelines.


• Prior exposure to automated test frameworks, hardware interfaces, and real-time data capture.

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.

This is an exempt salaried role.

Annual Salary Range

$74,000 - $172,725 USD

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] .

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.