Principal Software Engineer

About Valar Atomics At Valar Atomics, we're redefining what's possible in energy. Our mission is to make clean, high-temperature nuclear power scalable—unlocking abundant energy for industry, hydrogen, and next-generation manufacturing. We are a team of builders, engineers, and operators who believe nuclear energy should be fast to deploy, factory-made, and built for the real world. Our first pilot plant in Orangeville, Utah will demonstrate how advanced nuclear systems and fuel fabrication can power the future. Joining Valar Atomics means becoming part of a company where autonomy, ownership, and impact exist at every level. The Team As part of the Engineering organization, Software Engineering builds the internal platforms and tools that power reactor design, fuel manufacturing, licensing, and plant operations. The team partners directly with engineering, manufacturing, and operations to deliver full-stack software, integrate enterprise systems, and preserve traceability from requirement to as-built. The Role The Principal Software Engineer will own the technical architecture of the operating system for Valar—the telemetry systems that capture every second of reactor and fuel test data, the streaming backbone that moves it, the simulation platforms our reactor engineers design with, and the enterprise systems that run the company. You will set the direction the rest of our software engineers build against, take the hardest problems yourself, and work directly with reactor and fuel engineers, systems engineering, licensing, manufacturing, supply chain, and operations to understand how they actually work and then build the tooling that makes them faster. This position will be located in Torrance, California, with regular travel to our Orangeville, Utah pilot plant. Key Responsibilities • Own the end-to-end architecture of Valar's software platform across telemetry, streaming, simulation, and enterprise systems, and make the build-versus-buy calls that shape it for the next decade. • Design and build high-volume telemetry ingestion for reactor test stands, fuel manufacturing, and instrumentation—high-rate time-series at scale, with source timestamps, units, quality, and ordering preserved end to end. • Architect the streaming backbone that carries operational data to analytics, simulation, monitoring, and enterprise consumers, and engineer it for throughput, backpressure, replay, and recovery. • Support the simulation and modeling platform: Campaign management, compute scheduling, and reproducible, traceable results engineers can defend to regulators. • Architect and build full-stack services and web interfaces that engineers, operators, and technicians use daily, and integrate the commercial systems the company runs on (PLM, ERP, MES, document and records management) over REST, GraphQL, and event-driven interfaces. • Design data models, interfaces, and access boundaries that keep engineering, manufacturing, test, and quality records consistent, auditable, and usable across every team that needs them. • Establish the engineering practices this platform depends on—deployment, observability, testing, on-call, and software quality standards appropriate to a regulated environment. • Use AI coding agents and assistants as a core part of how you work, and set the standard for how the team verifies what they produce. • Set technical direction, lead design and code reviews, and mentor engineers as the software organization grows around you. Basic Qualifications • 10+ years of relevant experience writing software and deploying it to a production environment, including significant time as the technical owner of a platform or major system. • Demonstrated experience designing and operating high-volume telemetry or time-series systems—instrumentation, test, industrial, vehicle, or comparable high-rate data. • Demonstrated experience with high-volume streaming and event-driven architectures (Kafka, Pulsar, Kinesis, Flink, or similar), including throughput, backpressure, ordering, and replay concerns. • Experience building or operating simulation, modeling, or scientific computing platforms—orchestration of computational codes, batch and distributed compute, and reproducible results management. • Experience building enterprise and engineering software: full-stack services, web interfaces, and integration with commercial systems of record. • Demonstrated skill in both typed (like Java, C#, Go, C++, or Rust) and untyped (like Python or JavaScript) languages. • Proven track record driving architecture and technical decisions across multiple teams and stakeholders. • Working experience with cloud and containerized deployment, infrastructure as code, and CI/CD. • Deep understanding of computer science fundamentals, including algorithms, data structures, distributed systems, and data modeling. • Hands-on experience shipping production work with AI coding agents and assistants (Claude Code, Cursor, Copilot, or similar), and the judgment to verify what they produce before it lands. • Strong communication skills: open to the opinions of others, willing to bring your own creative ideas for solutions, and ready to own and rectify mistakes. • Bachelor's degree in computer science, engineering, mathematics, or a scientific discipline, or equivalent professional experience. Preferred Skills and Experience • Experience at a hardware, manufacturing, aerospace, energy, or heavy-industrial company where software served a physical system and downtime had physical consequences. • Familiarity with industrial data sources and protocols—historians, OPC UA, MQTT, Modbus—and the security boundaries between operational and enterprise networks. • Experience with HPC scheduling, GPU compute, or large-scale batch orchestration. • Familiarity with regulated or quality-controlled environments and the software implications of NQA-1, GAMP 5, or 21 CFR Part 11. • Experience integrating PLM, ERP, MES, LIMS, or document control systems, and a healthy skepticism about vendor claims. • Experience with Git, Docker, Kubernetes, and deployment to both cloud and on-premises infrastructure. • Experience building with LLMs and agents rather than just coding with them—retrieval over technical documents, agentic workflows, evaluation harnesses, or tool integrations. • Experience growing a software team or function from its early stages, including hiring and mentorship. • A point of view on where AI-assisted development helps, where it doesn't, and how to verify agent output in an environment where records end up in front of regulators. Tell us about it. What We Offer • Competitive base salary • Equity ownership in a rapidly growing advanced energy company • Comprehensive medical benefits • Unlimited PTO • Free daily lunch and dinner provided onsite • Generous PPE stipend • High-impact startup environment with significant ownership and autonomy • Opportunities for rapid career growth and internal advancement • Direct collaboration with experienced operators, engineers, and industry leaders • The opportunity to help build and scale transformative energy technology from the ground up Equal Employment Opportunity Statement Valar Atomics is an equal opportunity employer. We consider all qualified applicants without regard to race, color, religion, sex, gender identity, sexual orientation, national origin, age, disability, veteran status, or any other protected status under applicable law. We are committed to providing a workplace free of discrimination and harassment and will provide reasonable accommodation as required by law. Applicants must be legally authorized to work in the United States as a U.S. citizen or lawful permanent resident (green card holder). Salary $195,000—$270,000 USD