Engineer I–IV, Thermal-Hydraulic Safety Analysis & V&V at X-energy in Rockville, MD

  • Company: X-energy
  • Location: Rockville, MD
  • Salary: $85K – $187K
  • Job type: full time
  • Workplace: onsite
  • Posted: 2026-10-07

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Job description

X-energy LLC conducts a thorough recruiting process and will never issue offers without interview to discuss qualifications and responsibilities. All applications will be submitted via our company career page, www.x-energy.com/careers/ . We will never ask you to provide payment information as part of the recruiting process. If anyone claiming to represent X-energy directs you in a manner otherwise, please contact us at www.x-energy.com/contact-us . Job Description This role supports the Risk Informed Safety Analysis team that performs nuclear safety analysis for X-energy technology (e.g., Xe-100) licensing and design, with particular emphasis on thermo-hydraulic analysis. Under the direction of senior engineers and team leads, the position contributes to safety evaluations including system and component thermo-hydraulic transient and accident analysis, analysis supporting safety function identification and Structures, Systems, and Components (SSC) safety classification, and deterministic safety assessments that inform PRA. The engineer performs assigned thermo-hydraulic safety analysis work supporting regulatory submittals, applies NRC regulatory guidance (including RG 1.203 and design-specific interim staff guidance) under supervision, and collaborates with engineering disciplines to help establish design requirements derived from safety analysis. The position also supports verification and validation (V&V) activities to ensure thermo-hydraulic analysis codes are appropriately qualified for their safety analysis applications. Depending on level, responsibilities include contributing to Phenomena Identification and Ranking Tables (PIRTs) for thermo-hydraulic phenomena, supporting scaling analyses, performing accident scenario evaluations using system codes, and helping establish thermal-hydraulic safety limits and margins in support of the safety case for TRISO fuel and high-temperature gas-cooled reactor technology. Job Profile Tasks/Responsibilities Perform assigned thermo-hydraulic safety analysis for designated systems and accident scenarios using approved system analysis codes and methodologies, in accordance with NRC regulatory guidance (RG 1.203) and X-energy procedures. Conduct transient and accident analysis evaluating core heat removal, coolant flow behavior, heat transfer mechanisms, and temperature distributions throughout the reactor system and key components for anticipated operational occurrences (AOOs), design basis events (DBEs), design basis accidents (DBAs), and beyond design basis events (BDBEs) to help demonstrate adequate core cooling, heat removal capability, and defense-in-depth. Support the development and maintenance of SSC safety classifications through thermo-hydraulic analysis, providing analytical results that demonstrate component performance and safety function capability during accident scenarios and operational transients. Contribute to the development and maintenance of Phenomena Identification and Ranking Tables (PIRTs) that identify and rank thermo-hydraulic phenomena important to reactor safety for various accident scenarios and operational transients. Support scaling analyses that demonstrate applicability of experimental thermo-hydraulic data and analytical methods to the Xe-100 design, and help document the technical basis for code applicability. Assist in establishing thermo-hydraulic safety limits, safety margins, and acceptance criteria for safety analyses based on regulatory requirements, fuel temperature limits, material temperature limits, and fission product barriers. Support probabilistic risk assessment (PRA) activities by providing deterministic thermo-hydraulic analysis results and supporting the integration of deterministic and risk-informed approaches. Support development of technical documentation for regulatory submittals, including topical reports, safety analysis reports, code applicability reports for thermo-hydraulic codes, and responses to NRC requests for additional

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