Software Engineering Manager - Simulation

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.

About The Role

Radiant is seeking a

Software Engineering Manager for Simulation

to build and lead the engineering team responsible for reactor physics modeling, thermal-hydraulics simulations, and Digital Twin development. In this role, you will scale a high-performing team while maintaining technical depth, ensuring our simulation infrastructure enables Radiant to design, test, and validate reactor systems—accelerating our path to commercialization.

Responsibilities and Duties

- Build, lead, and mentor a team of simulation engineers developing thermal, hydraulic, and nuclear models for reactor and reactor subsystem physics.

- Guide technical architecture and implementation for simulation systems.

- Scale software infrastructure to support Digital Twin simulation, visualization, and data processing capabilities.

- Define and own the technical roadmap for thermal and safety analysis simulation. Develop and execute a strategy for model tuning as models and model frameworks change.

- Foster a culture of technical excellence by establishing best practices for simulation software development, code quality, and testing.

- Collaborate cross-functionally with Hardware, Nuclear, and Electrical engineering teams to accelerate software-in-the-loop and hardware-in-the-loop testing capabilities.

- Own team delivery of mission-critical internal simulation products while ensuring sustainable development practices and technical debt management.

- Recruit, develop, and retain top engineering talent and build a high-performance team culture.

Required Qualifications

- 7+ years of professional software engineering experience with significant depth in simulation, scientific computing, or physics-based modeling. - 2+ years of people management experience leading engineering teams. - Strong technical background in programming languages such as Python, Rust, C#, or C/C++, with the ability to review code and guide architectural decisions.

- Experience building and scaling highly technical engineering teams.

- Familiarity with simulation tools, physics-based modeling, numerical methods, or computational science sufficient to guide technical strategy.

- Familiarity with numerical solvers, visualization frameworks, and automated testing approaches for scientific software.

- Strong foundation in software engineering best practices, including version control, code review, and CI/CD pipelines.

- Proven ability to balance hands-on technical contributions with team leadership and people development.

- Bachelor's degree in physics, mechanical engineering, computer science, or a similar field, or equivalent experience

Preferred Qualifications

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

- Experience managing teams working on simulation or computational modeling, parallel computing, or high-performance computing.

- Background with modern simulation frameworks, finite element analysis, or computational fluid dynamics tools.

- Track record of successful cross-functional collaboration with Hardware, Nuclear, and Electrical engineering teams.

- Strong communication and stakeholder management skills with the ability to translate technical complexity for diverse audiences.

- Experience with Machine Learning, Deep Learning, AI, or other probabilistic modeling techniques.

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'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% 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.

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.