System Engineer

ABOUT SUBCRITICAL SYSTEMSSubcritical Systems, Inc. is a venture-backed startup in Austin, Texas building accelerator driven systems and the only US commercial manufacturer of accelerator cavities. What SpaceX did for rockets, we plan to do for accelerator cavities and commercialize across applications of power production, medical isotopes, semiconductors and waste transmutation.We are in the process of building the Energy Amplifier, a novel nuclear fission system in which a particle accelerator drives a subcritical core, making meltdown physically impossible for clean power production. Due to its inherent safety, our system has a more streamlined licensing process. Our founding team includes successful entrepreneurs with a track record of building several multibillion dollar companies in deep-tech, and scientists who were leading U.S. national labs with deep experience in accelerator & nuclear technologies.We are actively hiring to expand our team as we work toward licensing, regulatory submissions, and construction of our first energy amplifier. More information is available at subcritical.com.ROLE SUMMARYThis role sits at the convergence of software engineering, applied AI, and deep-tech hardware development. We are looking for an engineer who is as comfortable writing production code as they are thinking about how AI can fundamentally reshape the way complex systems are designed, reviewed, and built. You will join a lean, high-velocity team that prizes working hardware over documentation and you will be handed real problems from day one.Your initial mandate is to build AI-driven workflows that accelerate our CAD design and engineering review cycles. SSI's accelerator and reactor subsystems involve thousands of interdependent components, superconducting solenoid magnets, RFQ linacs, cryoplant infrastructure, shielding assemblies, each with tight geometric, thermal, and regulatory tolerances. Reducing the friction in how our engineers interact with that complexity is a direct mission contribution.Beyond CAD, the scope expands rapidly. SSI is building an AI agent pipeline (SETH) to orchestrate engineering tasks across the program, and this role is a foundational contributor to that architecture. Over time, you will extend AI-assisted workflows into accelerator systems commissioning, nuclear regulatory documentation, procurement analysis, and operational readiness, a surface area that very few engineers anywhere in the world will ever get to work on.This role reports to the Chief Operating Officer and sits inside Engineering Operations. You will work daily alongside mechanical, accelerator, and systems engineers, translating domain complexity into software that makes them faster.If you want to write code that physically changes what gets built, and you have the intellectual range to operate in an environment spanning SRF cavity tolerances, NRC regulatory pathways, and LLM context management, this role was designed for you.KEY RESPONSIBILITIESCAD and Design Workflow Automation • Design and deploy AI-assisted CAD review pipelines that parse geometry, models, and design documentation, flag interface conflicts, and surface design violations across systems, sub-systems, and components. • Build LLM-powered tooling that integrates with CAD environments (Fusion 360, SolidWorks, NX) to accelerate documentation, BOM generation, and change-log drafting. • Develop automated workflows for taking engineering drawings, specifications, and vendor data as inputs to produce AI-generated CAD models and associated drawings. • Instrument and track CAD workflow metrics to identify bottlenecks and measure cycle time reduction.Program-Wide AI Agent Architecture • Contribute to SETH, SSI's internal Systems Engineering Thinker AI agent pipeline, extending its capabilities across engineering, operations, and deployment workstreams that automate all design documentation. • Build agentic workflows for procurement analysis, parsing RFP responses, surfacing schedule risks, and flagging vendor compliance gaps against program requirements. • Develop AI tooling for accelerator subsystem commissioning support, including anomaly detection, parameter sweep analysis, and real-time operational monitoring interfaces.Nuclear and Regulatory Workflow Integration • Partner with the regulatory team to build AI-assisted tools for NRC Part 70/Part 30 documentation drafting, compliance cross-referencing, and submission preparation. • Develop AI agents and tools that make auditability of design work easy and traceable. • Identify and implement workflow automation opportunities across the energy amplifier island and accelerator design and operational readiness workstreams. QUALIFICATIONSRequired • 3+ years of software engineering experience with a strong Python foundation and production-quality code standards. • Demonstrated experience building with LLMs prompt engineering, RAG architectures, agent frameworks (LangChain, LlamaIndex, or equivalent), and API