Senior Software Engineer, Applications

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's Enterprise Data team owns the company's internal data and operational software. We have built and shipped an internal operations platform used across the company, spanning procurement, manufacturing, quality, warehouse, finance, and people operations. It brings the company's operational data together in one place and puts modern, intelligent tooling in the hands of the people who run the business every day. Adoption is growing quickly, and it is fast becoming where work across the company gets seen, coordinated, and moved forward.

We are hiring a Senior Software Engineer to own and extend this applications platform. Our goal is to make operational data an asset the whole business can access and build applications that help teams work more efficiently. As Radiant grows into multiple facilities, the Enterprise Data team has a rare opportunity to expand its influence and stand up new operational tools enterprise-wide — the kind of elite, in-house software capability that gives top hardware companies a genuine edge. You'll ship features end to end, from schema to API to UI, for real users you can walk over and talk to, on a small, high-leverage team. We work closely with the business to define requirements and build systems that deliver, validating outcomes with the people who use them. Strong ownership and sound judgment matter as much as raw coding ability.

Responsibilities & Duties:

• Design and ship full-stack features across a modern Python asynchronous API and a single-page TypeScript frontend, backed by a relational database and the company data warehouse.

• Own and extend the platform as a product, translating operator, buyer, and finance workflows into software that removes toil rather than adding process, and sitting with those users where they work to get it right.

• Integrate the platform with manufacturing execution, finance, procurement, and identity systems through REST APIs, GraphQL, and webhooks, including punch-out purchasing flows and material traceability.

• Build AI-native features by extending our natural-language-to-structured-query-language (SQL) assistant, agent task queues, and streaming tool-use loops, and by designing product surfaces where automated agents and people work on the same data.

• Own access control, role-based access control (RBAC), and audit for the secure handling of sensitive operational, compensation, and financial data.

• Write tested, maintainable code and run services on Kubernetes, handling authentication, authorization, and observability with the care an internal platform of this reach demands.

• Help expand the platform's reach as Radiant grows, standing up new operational tools and quality-of-life applications that improve efficiency across the enterprise.

Required Qualifications & Skills:

• Bachelor's degree in computer science or a similar field, or equivalent experience.

• 5+ years of software engineering experience, with significant full-stack work.

• Strong Python skills building production web services, including API design, asynchronous patterns, relational databases, and migrations.

• Solid frontend skills with a modern component-based framework and TypeScript, with the ability to build polished, functional UI without a dedicated frontend team.

• Experience integrating with third-party systems, including OAuth and single sign-on (SSO), REST and GraphQL APIs, and webhooks.

• Product sense, meaning you make good decisions about what to build with limited direction, and you ship.

Desired Qualifications & Skills:

• Experience building internal tools or operations software, especially in manufacturing, logistics, or finance domains.

• Experience building large language model (LLM) powered features, including tool-use loops, streaming, retrieval, and guardrails.

• Experience with real-time or collaborative features, data visualization, or rich editor surfaces.

• Background in hardware, aerospace, defense, or nuclear, and experience in regulated environments such as the Export Administration Regulations (EAR) or the International Traffic in Arms Regulations (ITAR).

• Comfort with Kubernetes, containers, and owning what you ship in production.

Additional Requirements:

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

• Must work 100% onsite at El Segundo headquarters.

• 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.