Principal Engineer, Safety Methods

TerraPower LLC.; Bellevue (WA); On-site; USD 150,000 - 230,000; Full time

Job summary

TerraPower LLC in Bellevue, WA seeks a Principal Engineer, Safety Methods to lead development and deployment of plant-scale thermal-hydraulic analysis methods and models for Natrium reactor. You will validate models, perform scaling analyses, and ensure quality through V&V with cross‑functional teams.

The role requires 8+ years in system-level thermal-hydraulic analysis, experience with RELAP5-3D/TRACE, and strong modeling and communication skills.

Qualifications

• Degree in Mechanical, Nuclear, Chemical Engineering with 8+ years in system-level thermal-hydraulic analysis and code assessment.
• Experience with experimental thermal-hydraulic data analysis and uncertainty evaluation.
• Strong communication and ability to manage multiple validation tasks in parallel.

Responsibilities

• Verify, validate, and quantify uncertainty for plant-scale thermal-hydraulic analysis tools.
• Develop and execute code assessment plans with validation matrices and quantitative comparisons.
• Perform scaling analyses to map test data to reference conditions.
• Interpret experimental data to support model validation and gap closure.
• Collaborate with test engineering to align model gaps with experiments.
• Document V&V methodologies, results, and uncertainties for design and regulatory submittals.
• Mentor junior engineers in system modeling and validation practices.

Skills

Thermal-hydraulics

Code assessment

Uncertainty quantification

RELAP5-3D

TRACE

SAS

SQA/NQA-1

Mentoring

Computation modeling

Education

Bachelor’s degree in Mechanical, Nuclear, or Chemical Engineering

Tools

RELAP5-3D

TRACE

SAS

System analysis tools

Job description

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, Safety 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, computational methods, and scaling analysis supporting benchmarking computational models against experimental data.

Responsibilities

• Support verification, validation, and uncertainty quantification activities for plant scale thermal‑hydraulic analysis tools.
• Develop and execute code assessment plans, including validation matrices, test selection, and quantitative comparison methodologies.
• Perform scaling analysis to evaluate the applicability of test data to reference system conditions, including assessment of similarity criteria and scaling distortion.
• Interpret and apply experimental data from separate effects and integral test facilities to support model validation and closure of technical gaps.
• Define validation needs, develop test requirements, and collaborate closely with test engineering teams to ensure alignment between model gaps and experimental programs.
• Document V&V methodologies, model assumptions, validation results, and uncertainty analyses for internal design processes and regulatory submittals.
• Collaborate with multidisciplinary teams to support plant design, safety analysis, and licensing workflows.
• Apply and improve TerraPower’s SQA and NQA1 modeling quality practices and ensure traceability and configuration control of analysis inputs, models, and results.
• Mentor junior engineers in system modeling, validation methodologies, and best practices in code assessment.

Key Qualifications and Skills

• Degree in Mechanical, Nuclear, Chemical Engineering, or similar field, with 8 plus years in the field of system‑level thermal‑hydraulic analysis and code assessment for nuclear or complex energy systems.
• Demonstrated experience in code assessment, including model‑to‑test comparison, validation metric development, and uncertainty quantification.
• Hands‑on experience working with experimental thermal‑hydraulic data, including data analysis, uncertainty evaluation, and comparison against system‑level predictions.
• Proficiency with system analysis tools (e.g., RELAP5‑3D, TRACE, SAS, or equivalent) applied to plant‑scale transient and steady‑state evaluations.
• Strong foundation in thermal‑fluid and reactor system behavior considerations relevant to advanced reactor designs.
• Experience performing scaling analysis to ensure appropriate translation test‑scale phenomena, including application of similarity criteria and detailed scaling distortion impact qualifications.
• Experience developing validation strategies, defining data needs, and coordinating with experimental programs.
• Experience with SQA and NQA‑1 quality assurance practices for modeling workflows is highly preferred.
• Strong analytical thinking, clear technical communication, and the ability to manage multiple validation tasks in parallel.

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.
• 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%

TerraPower’s technology is controlled for export by various agencies of the U.S. Government. TerraPower must evaluate applicants who are foreign nationals (other than asylees, refugees, or lawful permanent residents) in accordance with U.S. Government export control requirements. To facilitate TerraPower’s export control reviews, you will be asked as part of the application process to identify whether