Senior Mechanical Engineer

Thanks for your interest in Oklo! We are searching for a Sr. Mechanical Engineer to join our fuel recycling engineering team within Oklo’s Recycling Division. Position Description You will serve as Oklo’s technical expert for high-temperature process piping, pressure vessels, and pressure-retaining components supporting the Oak Ridge Fuel Recycling Facility (OFRF). You will own the mechanical design basis, analysis, code compliance, and technical interfaces for these systems from early design through fabrication, testing, installation, commissioning, and operational support. The work includes demanding hot-cell, molten-salt, inert-atmosphere, vacuum, and thermal-cycling service conditions. This role is for a technically rigorous mechanical engineer who is comfortable working from first principles, developing and reviewing detailed analytical models, and owning mechanical equipment designs from early concepts through fabrication, testing, hot-cell installation, and operation. Success requires strong engineering judgment, hands-on design capability, clear communication, and the ability to balance technical performance, safety, remote maintainability, manufacturability, schedule, and cost in a fast-moving environment. Specific responsibilities may include: Serve as Oklo’s technical expert for high-temperature piping, pressure vessels, pressure boundaries, and their supporting components within the OFRF. Translate process temperatures, pressures, chemistry, flow conditions, vacuum and inert-gas requirements, operating cycles, and upset conditions into the piping and vessel design basis, applicable codes, load combinations, service life, and acceptance criteria. Perform and review piping stress and flexibility analyses for sustained, thermal, pressure, seismic, displacement, and other applicable loads, including equipment nozzle loads and support reactions. Perform and review pressure vessel analyses for internal and external pressure, local loads, nozzle loads, thermal gradients, buckling, fatigue, creep, and cyclic service, including design-by-analysis when appropriate. Perform and review steady-state and transient thermal analyses addressing heat loss, insulation, heat tracing, temperature gradients, heat-up, cooldown, and abnormal thermal conditions. Select and qualify materials for high-temperature and corrosive service, considering molten-salt compatibility, oxidation, thermal aging, creep, fatigue, radiation exposure where applicable, weldability, and fabrication constraints. Design and review vessels, piping, nozzles, flanges, closures, transitions, supports, anchors, restraints, expansion joints, bellows, penetrations, and other pressure-boundary components. Define piping layout, support, restraint, slope, drainability, isolation, inspection, and access requirements needed to manage thermal expansion and support safe operation and maintenance. Coordinate piping and vessel interfaces with process equipment, hot-cell penetrations, confinement boundaries, structures, utilities, and instrumentation; incorporate remote connection, inspection, isolation, removal, and replacement provisions where personnel access will be limited. Develop and review calculations, specifications, piping material classes, line lists, vessel data sheets, drawings, fabrication details, and technical requirements. Review supplier and subcontractor calculations, models, drawings, material selections, weld details, fabrication procedures, and inspection plans; provide technical direction and resolve piping and vessel design issues. Establish fabrication and quality requirements, including material traceability, welding, heat treatment, dimensional control, nondestructive examination, pressure testing, leak testing, and final acceptance. Develop procurement specifications, statements of work, technical bid evaluations, and supplier acceptance criteria for piping and vessel packages. piping and vessel input to design reviews, failure-mode and constructability evaluations, engineering changes, supplier deviations, nonconformances, requests for information, and field changes. Support commissioning, troubleshooting, and root-cause evaluations involving high-temperature piping, pressure vessels, and pressure boundaries. Mentor other engineers and provide technical leadership in high-temperature piping and vessel design, analysis, materials, fabrication, and engineering judgment. Minimum Qualifications: Bachelor’s degree in Mechanical Engineering or a related engineering discipline. 10+ years of mechanical engineering experience with process piping, pressure vessels, or high-temperature systems, including responsibility for piping stress, pressure vessel, thermal, or mechanical stress analyses. Working knowledge of applicable ASME codes and standards, including ASME B31.3 and ASME Boiler and Pressure Vessel Code Section VIII. Strong understanding of thermal expansion, fatigue, creep, buckling, nozzle loads, pipe supports, pressure boundaries, and elevated-temperature material behavior. Experience developing and reviewing calculations, specifications, data sheets, drawings, and fabrication-ready design packages. Experience with materials selection, welding, fabrication, nondestructive examination, pressure testing, and inspection of piping or vessels. Ability to independently evaluate analytical results, code compliance, design assumptions, failure modes, and technical margins. Experience coordinating piping and vessel interfaces with process, structural, equipment, instrumentation and controls, operations, and supplier teams. Strong technical writing, communication, and engineering judgment. Eligibility to work in the United States without sponsorship. Bonus Qualifications: Master’s degree or Ph.D. in Mechanical Engineering or a related technical discipline. Professional Engineer registration or the ability to obtain Tennessee licensure. Experience with molten-salt, inert-gas, vacuum, nuclear hot-cell, or fuel-cycle systems and with elevated-temperature or corrosion-resistant alloys. Experience with ASME Section VIII Division 2, design-by-analysis, fatigue, buckling, creep, seismic qualification, or coupled thermal-mechanical analysis. Experience with analysis tools such as CAESAR II, AutoPIPE, ANSYS, Abaqus, COMPRESS, PV Elite, Mathcad, or similar software. Experience overseeing piping or vessel fabrication, supplier quality, weld qualification, nondestructive examination, and acceptance testing under nuclear quality assurance and design control processes. Competencies We are looking for a Sr. Mechanical Engineer who is: Technically rigorous: Comfortable working deeply in thermal analysis, stress analysis, equipment design, materials, codes, and failure modes. Analytically strong: Able to develop sound assumptions, understand model limitations, and determine whether calculated results make physical sense. A practical equipment designer: Comfortable moving between calculations, CAD models, drawings, fabrication details, testing, and physical hardware. Focused on hot-cell operability: Understands that equipment must be designed for remote installation, operation, maintenance, recovery, and replacement. A systems thinker: Able to understand how mechanical equipment interfaces with process systems, structures, piping, controls, shielding, confinement, and remote handling. Execution-oriented: Able to move equipment from concept through analysis, design, fabrication, testing, and installation. Collaborative and adaptable: Works effectively across disciplines, identifies technical issues early, and drives practical engineering decisions to closure. Mission- and safety-driven: Focused on delivering reliable, maintainable, and technically defensible equipment for nuclear fuel recycling applications. Who you are: A startup person: You aren’t driven by titles or hierarchy, and prefer efficiency to excess process. You don’t need or expect to have a lot of guidance but you enjoy working in a fast-paced team. If you prefer the culture and feel of a large organization, that is great, but you likely won’t enjoy working with us! There is plenty of important work and plenty of good opportunities with organizations like that. Motivated: You are self-motivated. You bring an enthusiasm to the team, and imbue a sense of passion that goes beyond clocking in and clocking out. This isn’t about a fake or arbitrary “pieces of flair” mentality or lack of work-life balance! It is about being a part of the vision and feeling a part of reaching team goals. A team-player: Oklo genuinely is a team. We aren’t about taking credit for ourselves, and we aren’t about pushing blame to others. We do incredible things because we work as a team. An excellent communicator: We need a person who is not only technically competent but also a clear and upbeat communicator. Creative: Being creative means that when things fall outside clear scopes or processes or problems arise without clear solutions, you are able to identify it as well as invent ways to solve a problem or fill a need without micromanagement. The successful person in this job will not only be creative, but also enjoy being creative and solving open-ended problems which may change day-by-day. Detail-oriented: This focus is a big part of excellence, consistency, and quality. Excellent grammar and spelling matter for both good communication as well as the image of the company that we put forward. About Oklo travel requirements: Oklo requires remote employees to travel to headquarters (Santa Clara, CA) twice a quarter annually, based on business or team needs, including attendance at team meetings, off-sites, and other company events or gatherings. For the first two weeks of onboarding, employees are required to be in person at headquarters in Santa Clara, CA. About Oklo compensation: Salary: $175,000-$210,000 Oklo offers flexible time off, equity, bonuses, competitive pay, 401(k), health insurance (with employer contribution), HSA, FSA, flexible work hours, wellness credits, and other benefits. This position may involve access to information subject to U.S. export control laws. Only applicants who meet the definition of a U.S. person under applicable laws may be eligible. About Oklo Inc.: Oklo Inc. is developing fast fission power plants to deliver clean, reliable, and affordable energy at scale; establishing a domestic supply chain for critical radioisotopes; and advancing nuclear fuel recycling to convert nuclear waste into clean energy. Oklo was the first to receive a site use permit from the U.S. Department of Energy for a commercial advanced fission plant, was awarded fuel material from Idaho National Laboratory, and submitted the first custom combined license application for an advanced reactor to the U.S. Nuclear Regulatory Commission. Oklo is also developing advanced fuel recycling technologies in collaboration with the U.S. Department of Energy and U.S. National Laboratories. #CHOP: Oklo’s Values Collaboration : We go further, together. We bring diverse perspectives, listen actively, and build trust through transparency and respect. We work across disciplines, sharing ownership to turn complex challenges into shared successes. Humility : We are team players who act for the good of the company and for the world. We are focused on our mission, not personal recognition. Ownership : We take pride in what we do and how we do it. We are proactive in finding solutions and see tasks through to completion. We are committed to delivering on our promises to provide clean, reliable, and affordable energy. Pathfinding : We chart new ground where no path exists by approaching challenges with curiosity, courage, and creativity while navigating ambiguity. Candidates should be aware that employment may be contingent upon successful completion of a drug screening, and employees may be subject to drug testing at any time in accordance with company policy and applicable laws. Recruitment Fraud Disclaimer Oklo is aware of recent recruitment fraud attempts targeting job seekers. Please be cautious of anyone claiming to represent Oklo who does not contact you from an official Oklo email address. All legitimate communications from our recruiting team— including application updates, interview requests, and job offers — will come exclusively from an @oklo.com email. Oklo will never ask for sensitive personal information, payments, or account credentials during the hiring process. If you receive suspicious outreach or have concerns about the authenticity of any communication claiming to be from Oklo, please contact us through the official channels listed on our website.