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Principal Probabilistic Risk Assessment Engineer

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Job Description

TITLE: Principal Probabilistic Risk Assessment Engineer


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. In addition, as a federal contractor, TerraPower has instituted an Affirmative Action Plan (AAP) in an effort to proactively recruit, hire, and promote women, minorities, disabled persons and veterans.

Principal Probabilistic Risk Assessment Engineer

The Principal Probabilistic Risk Assessment (PRA) Engineer reports directly to the Risk Assessment Manager. The Principal PRA Engineer will work with the Natrium Risk Assessment team and is responsible for performing PRA and severe accident analysis for the Natrium reactor design. The Principal PRA Engineer is primarily responsible for internal and external PRA work to be performed in coordination with deterministic safety analysis and other engineering disciplines/groups to design a reliable and safe plant. Additionally, the Principal PRA Engineer will use developed PRA models to provide risk information such as importance measures and changes in risk metrics to inform design and licensing decisions. Other engineering activities include, but are not limited to, contributing to the development of computational methodologies and models, participating in hazard analysis, participating in Phenomena Identification and Ranking Table (PIRT) exercises, and participating to Structures, Systems, and Components (SSC) classification, Licensing Basis Events (LBE) selection, and Defense-in-Depth (DID) Evaluations. The Principal PRA Engineer will be interacting with other groups via interviews, emails, meetings, and other avenues to develop the risk models and the position requires sound written and verbal communication skills.

This position requires an understanding of PRA principles and familiarity with the ASME/ANS PRA standard. While this position requires knowledge of sodium fast reactor technology, this knowledge can be obtained on the job through various in-house training workshops and interaction with TerraPower staff.


  • Manage PRA work performed inside and outside of TerraPower in coordination with plant design, deterministic safety analysis, and other disciplines.
  • Ensure that the PRA is appropriate and used for the reactor design and within regulatory requirements, guidance, and standards such as risk-informed performance-based technology guidance for Non-Light Water Reactors (RG 1.233 and NEI 18-04) and ASME/ANS Non-Light Water PRA standard.
  • Lead the development of planning and schedule for PRA related activities.
  • Provide technical guidance to engineers and managers on reliability and various PRA-related topics.
  • Participate in PRA peer reviews.
  • Lead the development of event and fault trees, in-vessel radiological transport models, containment transport models, and mechanistic radiological release categories for PRA models.
  • Work with an interdisciplinary team of engineers to establish core and reactor SSC functional, reliability, performance, safety, and quality requirements as well as support the overall design.
  • Establish and maintain documentation of model development and analysis results.
  • Perform engineering reviews of analyses and other engineering design media.
  • Develop containment fault trees and event trees to reflect most up to date design using CAFTA.
  • Group similar source terms for assignment to event sequence end states.
  • Perform risk integration using the PRA model to report risk metrics and importance measures.
  • Perform focused PRA analysis to support trade studies.
  • Perform hand calculations using first principles to assess and validate more complex models for system performance, containment performance, and radiological consequences.
  • Prepare topical reports describing PRA methods and analytical results for customers and regulators.
  • Deliver presentations for internal management and external customers and regulators.

Key Qualifications and Skills

  • B.S., M.S., or PhD in nuclear, mechanical, electrical, or aerospace engineering (or similar)
  • Fifteen years or more of experience in Probabilistic Risk Assessment
  • In-depth knowledge on PRA principles and the ASME/ANS Non-Light Water PRA standard.
  • In-depth knowledge on risk-informed performance-based regulations and applications.
  • In-depth knowledge of PRA fundamentals in data, human reliability, accident analysis, severe accidents, and source terms assessments.
  • Experience with PRA software: CAFTA in particular; SAPHIRE, Risk Spectrum, or other similar software still considered valuable.
  • Experience with performing assessments using codes such as GOTHIC, MELCOR, RADTRAD, or similar tools is a plus.
  • Demonstrated technical writing and communication skills.
  • Experience with sodium cooled reactors or other advanced reactors preferred.
  • Fluent in spoken and written English language.
  • A broad understanding of the various engineering disciplines and how they interrelate in the design of a Nuclear Power Plant.
  • High degree of trust, integrity, open communication, respect for others, and teamwork.

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 and/or standing 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 hrs./day

· Travel required: 0-5%

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 will not consider a foreign national from a country if it is impracticable to obtain timely Government export approval.

Job details

Salary Range Level 12: $157,405 - $218,119

Salary Range Level 13: $179,892 - $258,595

*Typically, our employee salaries are within .90 – 1.0 of the mid-point of the posted salary band. Any salary offered within the posted salary band is based on market data and commensurate with the selected individual’s qualifications and experience. This range is specific to Washington State.

Job Type: Full-time


  • Competitive Compensation
  • Salary, eligible to participate in discretionary short-term incentive payments
  • Comprehensive Medical and Wellness Benefits Medical
  • Vision
  • Dental
  • Life
  • Life and Disability
  • Gender Affirmation Benefits
  • Parental Leave
  • 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
  • Flexible Work Schedule

TerraPower Career and Benefits information: https://www.terrapower.com/contact-us/careers/

Please visit www.terrapower.com to apply

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