About Radiant

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.

About the role

Radiant is seeking a Senior Software Engineer to build the analysis tooling and data infrastructure that accelerates how our engineering teams design and validate the Kaleidos reactor. You'll work directly with reactor physics, materials, and systems engineering teams to understand their workflows, identify automation opportunities, and build tools that eliminate bottlenecks — from standardizing data inputs and outputs to integrating analysis codes like Attila into our materials database. This role is about understanding how our engineers and scientists work and building sharp, precision, practical tooling that makes them dramatically faster. You'll own the full lifecycle of these tools and platforms: scoping, building, iterating, and maintaining them as Radiant's analysis needs evolve.

Responsibilities and Duties:

• Partner with reactor design, materials, and systems engineering teams to map existing analysis workflows and identify high-value automation and tooling opportunities.

• Build and maintain data pipelines that connect analysis codes (including Attila and other neutronics/thermal tools) to Radiant's materials database and downstream post-processing systems.

• Standardize data input and output formats across analysis tools to reduce manual overhead and improve reproducibility.

• Develop post-processing and visualization tooling to help engineers quickly interpret simulation and analysis results.

• Own the integration between Attila and the materials database, ensuring data flows reliably and consistently between systems.

• Build lightweight automation to eliminate repetitive manual tasks across engineering workflows.

• Design and maintain APIs and data access layers that allow engineers to programmatically query analysis results and materials data.

• Establish data quality checks and validation frameworks to ensure analysis inputs and outputs meet engineering standards.

Required Qualifications and Skills:

• Bachelor's degree in computer science, physics, engineering, or a related technical field.

• 5+ years of software engineering experience, with a focus on tooling, data pipelines, or workflow automation.

• Expert proficiency in Python; familiarity with at least one of Rust, Golang, C++, or C#.

• Experience building data pipelines and integration layers between scientific or engineering software tools.

• Demonstrated ability to work directly with non-software engineers to scope and deliver tooling that solves real workflow problems.

• Familiarity with Git, Docker, Kubernetes, and CI/CD practices.

• Strong instinct for identifying the simplest solution that meaningfully improves engineering velocity.

Desired Qualifications and Skills:

• Experience in a hardware, defense, aerospace, energy, scientific environment, or other deep-tech environment.

• Experience building or integrating databases or engineering data management systems.

• Familiarity with data visualization and lightweight dashboard tools (Plotly, Streamlit, Grafana, Observable).

• Experience with columnar data formats (Parquet, Arrow) and analytical query tools (DuckDB, Trino, Spark).

• Familiarity with nuclear, neutronics, or radiation transport codes (e.g., Attila, MCNP, Serpent, OpenMC) or other physics simulation tools.

• Experience with workflow orchestration tools (Airflow, Argo Workflows, Prefect).

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.

Benefits and Perks

• 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: recruiting@radiantnuclear.com.

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.

Compensation Range: $158,000 - $219,450