Senior Engineer, Plant Thermal Hydraulics Methods

Job Title: Senior Engineer, Plant Thermal Hydraulics Methods

Location: Bellevue, WA

Type: Contract (yearlong) typically extends on a yearly basis

Compensation: $52.00 - $85.00

Work Model: Fully Remote – offsite

Hours: 40.0
Paid Holidays | PTO

Overview


System One is seeking a Senior Engineer, Plant Thermal Hydraulics Methods contractor to be part of a growing team supporting the design and licensing of our client’s 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. Other engineering activities include, but are not limited to, 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.

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.
• Support method qualification, 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 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 client’s SQA and NQA 1 modeling practices, ensuring traceability, configuration control, and reproducibility of methods.

• Degree in Mechanical, Nuclear, Chemical Engineering, or similar fields, with 5+ 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.

System One, and its subsidiaries including Joulé and Mountain Ltd., are leaders in delivering outsourced services and workforce solutions across North America. We help clients get work done more efficiently and economically, without compromising quality. System One not only serves as a valued partner for our clients, but we offer eligible employees health and welfare benefits coverage options including medical, dental, vision, spending accounts, life insurance, voluntary plans, as well as participation in a 401(k) plan.

System One is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender identity, age, national origin, disability, family care or medical leave status, genetic information, veteran status, marital status, or any other characteristic protected by applicable federal, state, or local law.

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