Mechanical Design Engineer – Reactor Internals (In-Vessel Shielding

X-energy is seeking a Mechanical Design Engineer responsible for the engineering design, analysis, and development of reactor vessel internals (RVI) shielding elements for X-energy's advanced high-temperature gas-cooled reactor. The role supports the design lifecycle from concept through detailed design, manufacturing support, testing, and commissioning while ensuring compliance with nuclear safety, quality, and regulatory requirements. The engineer will collaborate with cross-functional engineering teams to develop shielding component designs that satisfy structural, thermal, manufacturing, and integration requirements within the reactor vessel.

• Develop mechanical concepts and support the development of structures, systems, and components (SSCs) for nuclear products or facilities with a focus on nuclear safety.
• Identify, collect, and document applicable requirements, interfaces, design basis and criteria by coordinating with stakeholders and systems engineers; support identifying applicable industry codes and standards and project direction.
• Plan and perform analyses to ensure SSCs can perform their intended functions and meet technical specifications and design requirements.
• Perform computations using hand calculations and analytical tools for structural, thermal, hydraulic, and other scoping calculations to verify SSCs meet technical requirements.
• Integrate design activities across engineering teams, partners, and suppliers; perform supporting scoping and sizing to down select design features using consensus codes and standards.
• Create and maintain CAD-generated engineering models of reactor SSCs.
• Develop innovative mechanical solutions related to X-energy reactors, including pressure vessels and piping, reactor internals, nuclear fuel, and high-temperature materials such as graphite.
• Assess SSCs for manufacturability, assembly, and integration considerations under direction of project leads.
• Write and develop design documentation including design basis documents, technical reports, calculations, and drawings per applicable procedures.
• Develop verification and validation (V&V) plans for analytical tools and support qualification of toolsets.
• Work in accordance with X-energy quality procedures for design and configuration management to ensure project quality requirements are met.
• Provide independent reviews and acceptance reviews of engineering delivers and data; maintain professional demeanor in all communications.
• Perform other duties as assigned by the manager.

• Typically five years of experience in an engineering role.
• Bachelor’s degree in mechanical engineering or related engineering discipline from an accredited institution.
• A master’s degree in engineering or related field may be in lieu of two years of experience; a Ph.D. may be in lieu of three years of experience.
• Proficiency with engineering hand calculations; one or more years of hands-on experience developing and delivering hardware or manufacturing processes in a production environment.
• Experience with CAD and product lifecycle management (PLM) software (e.g., UG/NX, Solid Works, Pro-Engineer, Teamcenter, Windchill or similar).
• Experience designing mechanical or fluid systems, assemblies, or components.

• Professional experience in the commercial nuclear, naval nuclear, or advanced reactor industry.
• Experience designing reactor internals, in-core structures, shielding components, graphite assemblies, or other reactor vessel internal components.
• Familiarity with high-temperature reactor technologies, including gas-cooled or graphite-moderated systems.
• Experience in designing components subjected to combined thermal, structural, irradiation, and seismic loading.
• Knowledge of nuclear materials used in reactor internals (e.g., stainless steels, graphite, neutron shielding materials, high-temperature alloys).
• Experience developing mechanical designs in accordance with ASME Section III, NRC requirements, and nuclear quality assurance standards.
• Experience supporting component qualification, manufacturing, testing, and design verification for safety-related nuclear hardware.
• Experience working within multidisciplinary reactor design teams and coordinating interfaces across core, vessel internals, structural, thermal-hydraulic, and systems disciplines.

The salary range for this position is $115,000 - $140,000, commensurate with experience, education, and qualifications. Compensation varies by office location and region. Benefits include a robust package with a 401(k) plan with employer match, medical/dental/vision insurance, life and disability insurance, paid time off, and tuition reimbursement/professional development policy.

X-energy is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, protected veteran status, or disability. X-energy…