Job Title: Senior Safety Methods Engineer
Location: Bellevue, WA
Type: Contract, 12 months
Compensation: $37.00 - $74.00
Contractor Work Model: Onsite, remote available for exceptional non-local candidates.

Overview:
This role develops and qualifies system-level thermal-hydraulic analysis methods to support reactor safety and licensing work. Responsibilities include running steady-state and transient analyses to assess model performance and fidelity needs, integrating closure models and empirical correlations into existing frameworks, and identifying gaps through sensitivity studies to drive method improvements. The engineer also builds automated, repeatable workflows, documents methodologies and assumptions, collaborates across disciplines to align methods with design and safety analysis, and follows SQA/NQA-1 practices to ensure traceability, configuration control, and reproducibility.

Responsibilities:

• Support the design and licensing of the reactor by developing methods for Licensing Basis Events (LBE) analyses.
• Contribute subject matter expertise to the Sodium Fast Reactor (SFR) Program and other related projects.
• Develop system-level thermal hydraulic analysis methods, including modeling strategies, numerical approaches, and closure models.
• Perform steady-state and transient system-level analyses to assess models, methods, and their fidelity requirements.
• Support method qualification through numerical verification, applicability assessments, and performance characterization.
• Formulate and integrate closure models and empirical correlations into existing analysis frameworks.
• Identify modeling gaps and support method enhancements via sensitivity studies.
• Develop automated workflows and tools for model setup, execution, post-processing, and reproducible applications.
• Document modeling methodologies, assumptions, and numerical performance for licensing and design support.
• Collaborate across disciplines to ensure thermal hydraulic methods are integrated with plant design and safety analysis workflows.
• Apply and improve SQA and NQA 1 modeling practices, ensuring traceability, configuration control, and reproducibility.

• Degree in Mechanical, Nuclear, Chemical Engineering, or similar fields.
• 3+ years of experience in system-level thermal hydraulic modeling and method development for nuclear or complex energy systems.
• Experience with thermal hydraulic analysis tools such as RELAP5 3D, GOTHIC, SAS, or equivalent.
• Proven experience in developing or improving analysis methods, including numerical schemes and stability/accuracy optimization.
• Strong foundation in thermal fluids and reactor system behavior, especially in advanced reactor designs.
• Experience performing sensitivity analyses and identifying model gaps.
• Familiarity with scientific programming and workflow automation (Python, MATLAB).
• Knowledge of NQA 1 quality assurance standards for modeling workflows, including methodology documentation and configuration control.
• Strong analytical skills, clear technical communication, and ability to manage multiple development efforts.
• High integrity and trustworthiness, with openness in communication and teamwork orientation.

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.