Principal Engineer, Plant Thermal Hydraulics Methods

  TerraPower is a nuclear technology company based in Bellevue, Washington. At its core, the company is working to raise living standards globally through a more affordable, secure, and environmentally friendly form of nuclear energy along with innovations in medical isotopes to improve human health. In 2006, TerraPower originated with Bill Gates and a group of like-minded visionaries who evaluated the fundamental challenges to raising living standards around the world. They recognized energy access was crucial to the health and economic well-being of communities and decided that the private sector needed to take action and create energy sources that would advance global energy deployment. TerraPower’s mission is to be a world leader in new nuclear technologies, while developing innovators and future leaders in the nuclear field. As a result, the company’s activities in the fields of nuclear energy and related sciences are yielding significant innovations in the safety and economics of nuclear power, hybrid energy and medical applications – all for significant human health benefits.” TerraPower is seeking to hire highly motivated and forward-thinking professionals who are interested in focusing on advanced nuclear reactor research and development and influencing change within the nuclear power landscape and bringing forward the critical production of medical isotopes.  TerraPower is an Equal Opportunity Employer. We do not discriminate in hiring on the basis of sex, gender identity, sexual orientation, race, color, religious creed, national origin, physical or mental disability, protected Veteran status, or any other characteristic protected by federal, state, or local law.  Principal Engineer, Plant Thermal Hydraulics Methods This role supports the development, enhancement, and deployment of plant‑scale thermal‑hydraulic analysis methods and models for the Natrium reactor. Reporting to the Manager, Plant Thermal Hydraulics Methods, the principal engineer supports the creation, improvement and qualification of advanced system-level modeling approaches that enable accurate, robust prediction of plant behavior across operational and transient scenarios. The position requires expertise in system‑level thermal‑hydraulics, thermal‑fluids behavior, and the formulation of computational methods and closure models that represent complex reactor phenomena. Responsibilities Develop plant scale thermal hydraulic analysis methods, including modeling strategies, numerical approaches, and closure models. Perform steady-state and transient system level analyses to characterize model behavior, assess method performance, and define method fidelity requirements. Develop and maintain method qualification plans, including numerical verification, applicability envelopes, and performance characterization. Formulate and integrate closure models and correlations (e.g., heat transfer, pressure drop, mixing, component-level physics) into existing analysis frameworks. Identify modeling gaps and drive method enhancement priorities using Phenomena Identification and Ranking Table (PIRT), sensitivity studies, and multi-physics needs. Develop automated workflows and tools for model setup, execution, post processing, and repeatable method application. Collaborate with test engineering to define data needs that inform method development (not for validation purposes, but to guide model formulation and closure development). Document modeling methodologies, assumptions, method applicability, and numerical performance for design processes and licensing support activities. &l