Principal Engineer, Nuclear Methods

TerraPower LLC.; Bellevue (WA); On-site; USD 149,000 - 193,000; Full time

Benefits offered by this job

Competitive pay

Relocation assistance

401k plan

21 PTO days

Generous holiday schedule

Job summary

TerraPower LLC. seeks a Principal Engineer, Nuclear Methods to advance reactor design and simulation software for licensing and safety validation. You will lead development and analysis using state-of-the-art methods, collaborating across engineering teams and external partners.

The role emphasizes rigorous documentation, automation, and training of designers, with substantial emphasis on uncertainty and safety margins in fast-neutron reactor projects.

Qualifications

• Ph.D. and 5+ years in Nuclear Engineering or a related discipline.
• Master’s degree with 8+ years experience considered on case-by-case basis.
• Experience with fast reactor physics and design intuition.
• Experience with nuclear design/analysis methodologies (criticality, flux distributions, fuel management, etc.).
• Strong programming in Python, C++, Fortran is a bonus.
• Proven ability to integrate and automate simulation tools.

Responsibilities

• Create formal documentation of nuclear methods software requirements, design, implementation, and testing for licensing.
• Update, improve, and/or create software to satisfy licensing during V&V.
• Incorporate 3rd-party programs to support licensing in the simulation ecosystem.
• Design and execute sensitivity studies to understand modeling assumptions and physics coupling.
• Train and support reactor designers in the use of design software suite.
• Build methods to assess propagation of uncertainty and effects on safety margins.
• Enhance engineering team's ability to build models from simulation output.

Skills

Fast reactor physics

Nuclear design intuition

Deterministic transport

Stochastic transport

Python programming

C++ programming

Fortran programming

NRC QA experience

Education

Ph.D. in Nuclear Engineering

Master’s in Nuclear Engineering with 8+ years

Tools

DIF3D

MCNP

Serpent

PARTISN

MC2

ARMI

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, Nuclear Methods

TerraPower, LLC. is seeking a highly motivated Principal Engineer, Nuclear Methods. In this role, you will support the nuclear methods team:

• Create formal documentation of nuclear methods software requirements, design, implementation, and testing in support of licensing TerraPower reactors.
• Update, improve, and/or create software to satisfy all licensing requirements during the Validation and Verification (V&V) process
• Incorporate additional 3rd-party programs in our simulation ecosystem as necessary to support licensing
• Design and execute sensitivity studies to understand the effects and validity of various modeling assumptions, including meshing, physics coupling, transport options, cross section preparation, fission product models, spatial kinetics, etc., and adjust methods as necessary
• Train and support reactor designers and developers in the use of the design software suite
• Build and apply methods to assess the propagation of uncertainty and their effect on safety margins
• Enhance engineering team's ability to build models and make meaningful conclusions from simulation output through input tools, visualization, reports, etc.,

Key Qualifications and Skills

• Ph.D. and 5+ years of experience in Nuclear Engineering or a related discipline from an accredited university, or a Master’s degree with 8+ years of relevant experience
  
  • Candidates who do not meet all of the stated qualifications may be considered on a case-by-case basis based on the relevance, depth and applicability of their education and professional experience
  • Experience level may be partially substituted for advanced degree depending on position relevance
• Fast reactor physics and design intuition
• Experience in understanding and executing nuclear design/analysis methodologies, including criticality, flux/power distributions, fuel management optimization, reactivity coefficients, shielding, activation, control rod worth, detector response, and uncertainty analysis, ideally with a focus on fast-neutron reactors
• Excellent “under-the-hood” knowledge of the methods of reactor physics analysis (deterministic and stochastic particle transport, isotopic depletion, perturbation theory, nuclear data, kinetics, etc.)
• Experience with some nuclear engineering software such as DIF3D, MC2, PARTISN, MCNP, Serpent, SCALE, PARCS, APA, CASMO, DRAGON, ARMI, etc. preferred
• Strong computational expertise required: we consider computers to be the universe at our fingertips rather than burdensome necessities
• Strong programming skills in any language required, preferably in scientific computing, Python, C++, and Fortran skills are a bonus
• Proven ability to integrate and automate simulation tools
• Demonstrable capabilities with fundamental software development tools (e.g. IDEs, version control, profilers, debuggers, documentation builders, packaging tools)
• Experience interacting on nuclear methodology with the NRC under an ASME NQA-1 compliant QA environment preferred
• Good working knowledge of general numerical methods and applied mathematics (e.g. PDEs, numerical stability, statistics, numerical analysis, dynamics)
• Strong formal technical documentation skills required
• Ability to consistently deliver to an aggressive schedule
• Self-motivated: able to seek out tasks and produce value aligned with team goals without waiting for next assignment
• Passion for and dedication to software best practices
• Willingness to openly give and accept professional criticism through code reviews and other venues
• 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.
• 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 you are a U.S. Citizen or national, asylee, refugee, or lawful permanent resident of the United States. Government export authorization approval times vary. Based on the business needs for a particular position, TerraPower may not consider a foreign national from a country if it is impracticable to obtain timely Government export approval.

Job details

Salary Range: $148,722 – $193,146

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.

• Competitive Compensation
• Salary, eligible to participate in discretionary short-term incentive payments
• Comprehensive Medical and Wellness Benefits
  • Medical
  • Vision
  • Dental
  • Life and Disability
  • Gender Affiliation Benefits
• 401k 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

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The application deadline for this role is September 8, 2026