Senior Safety Methods Engineer

Senior Safety Methods Engineer Bellevue, Washington, United States 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. The Senior Safety Methods Engineer is part of a growing team supporting the design and licensing of the Natrium Demonstration reactor and is primarily responsible for developing methods to perform Licensing Basis Events (LBE) analyses. The Senior Engineer may also contribute subject matter expertise to other projects under development by the TerraPower Sodium Fast Reactor (SFR) Program. Other engineering activities include, but are not limited to, closure model formulation, system transient codes development and maintenance, performing reactor transient analyses, code benchmark with Integral Effect Tests (IETs) or Separate Effect Tests (SETs), scaling analysis, software commercial‑grade dedication, contributing to code assessment and adequacy evaluation, as well as performing verification and validation activities. Under the TerraPower SFR Program, the Senior Engineer receives administrative, technical, and project supervision from the Manager of Plant Thermal Hydraulics Methods. Responsibilities Develop system‑level 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. Support method qualification, including numerical verification, applicability envelopes, and performance characterization. Formulate and integrate closure models and empirical correlations (e.g., heat transfer, pressure drop, mixing, component‑level physics) into existing analysis frameworks. Identify modeling gaps and support method enhancement using and sensitivity studies. Develop automated workflows and tools for model setup, execution, post processing, and repeatable method application. Document modeling methodologies, assumptions, method applicability, and numerical performance for design processes and licensing support activities. Work across disciplines to ensure thermal hydraulic methods integrate effectively with plant design, safety analysis, and coupled simulation workflows. Apply and improve TerraPower’s SQA and NQA 1 modeling practices, ensuring traceability, configuration control, and reproducibility of methods. Key Qualifications and Skills Degree in Mechanical, Nuclear, Chemical Engineering, or similar fields, with 3+ years of experience in system‑level thermal hydraulic modeling and method development for nuclear or complex energy systems. Demonstrated experience in developing or improving analysis methods, including numerical scheme development, closure model formulation, and stability/accuracy optimization strategies. Experience performing system‑level thermal hydraulic analyses using tools such as RELAP5 3D, GOTHIC, SAS, or equivalent, with the ability to extend or tailor modeling approaches within these frameworks. Strong foundation in thermal fluids and reactor system behavior, including complex thermal hydraulic phenomena relevant to advanced reactor designs. Experience in sensitivity analyses and model gap identification that support method development priorities. Familiarity with scientific programming and workflow automation (e.g., Python, MATLAB). Familiarity with NQA 1 quality assurance for modeling workflows, including documented methodologies, configuration control, and model traceability. Strong analytical thinking, clear technical communication, and the ability to support multiple method development efforts in parallel. The successful candidate will possess a high degree of trust and integrity, communicate openly and display respect and a desire to foster teamwork. This position is subject to qualification requirements in accordance with ANSI/ANS 3.1. Candidates must meet the minimum education and experience criteria applicable to the role, including relevant nuclear industry experience where required. Verification of data will be part of the hiring process. Job Functions Job Functions are physical actions and/or working conditions associated with the position. These functions may also constitute essential functions for the job which the employee must be able to fulfill, with or without accommodation. Information provided below is to help describe the job so that the applicant has a reasonable understanding of the job duties/expectations. An applicant's ability to perform and/or tolerate these actions and conditions will be discussed and workplace accommodations may be made on a case‑by‑case basis following an individualized assessment of the applicant and other considerations, including but not limited to any governing safety standards. Motor Abilities: Sitting for extended periods, bending/stooping, grasping/gripping, fine motor control (hands) Physical exertion and/or requirements: Minimal, with ability to safely lift up to 25 pounds. Repetitive work: Prolonged Special Senses: Visual and audio focused work Work Conditions: Stairs, typing/keyboard, standard and/or sitting working environment of >8 hours/day Travel required 0‑10% Job details Salary Range: $138,685 – $208,027 Any salary offered within the posted salary band is based on market data and commensurate with the selected candidate’s qualifications and experience. This range is specific to Washington State. Job Type: Full‑time Benefits: Competitive Compensation Salary, eligible to participate in discretionary short‑term incentive payments Comprehensive Medical and Wellness Benefits Medical Vision Dental Life and Disability Gender affirmation Benefits Parental Leave 401 k Plan Generous Paid Time Off (PTO) 21 days of annually accrued PTO Generous Holiday Schedule 10 paid holidays Relocation Assistance Professional and Educational Support Opportunities TerraPower Career and Benefits information:

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