Thermal Engineer

Last Energy is a pioneering US technology company focused on fleet-wide deployment and operation of next-generation nuclear assets. We are revolutionizing nuclear power delivery for rapid deployment and scalability. We are seeking a Thermal Engineer to design the pressure-boundary hardware in our micro nuclear power plant, built on proven pressurized water reactor (PWR) technology. That means heat exchangers, piping, pressure vessels, and the primary loop that connects them. This is a hardware role. The engineer in this seat turns thermal performance requirements into components that can be manufactured and deployed, starting from hand calculations and first principles, and saving detailed analysis for detailed design. Working alongside our analysis and structural engineers, this person takes designs from model to physical hardware. Key Duties & Responsibilities • Lead the conceptual design, analysis, and execution of critical thermal-mechanical components and systems for our advanced power plant • Drive mechanical design of components subject to thermal loading • Own the design of heat exchangers, piping networks, fluid storage tanks, and other pressure-boundary equipment, and partner with our structural engineers on validation, ensuring structural integrity, thermal performance, and design safety across key reactor components • Perform thermal and structural analyses (thermal stress, fatigue, and thermal expansion) to validate component designs against pressure, temperature, and cyclic loading requirements • Contribute directly to the mechanical design and optimization of critical thermal components, translating thermal performance requirements into manufacturable, deployable hardware • Collaborate daily with a multidisciplinary team to integrate thermal-mechanical solutions into cohesive, plant-level designs • Support material selection, tolerancing, and design-for-manufacturing decisions for components operating under high-temperature and high-pressure conditions • Operate autonomously, driving projects from concept to design verification in a startup culture that values speed, ingenuity, and accountability Qualifications • BS or MS in Mechanical Engineering or related field, with 7+ years of hands-on industry experience designing components under thermal and mechanical loading • Proven experience as a Mechanical, Thermal, or Design Engineer working on thermal systems components within power plant, nuclear, or complex industrial systems • Proficiency in 3D CAD software (e.g., Autodesk Inventor, SolidWorks, Siemens NX, PTC Creo) for mechanical design of thermal-mechanical components and assemblies • Proficiency in analysis software (e.g., ANSYS Mechanical, Abaqus, SolidWorks Simulation) for structural and thermal stress analysis • Solid working knowledge of heat transfer, thermodynamics, and mechanical design principles (fatigue, fracture, thermal expansion, pressure-boundary design) • Experience with pressure vessel or piping design codes a strong plus (ASME BPVC Section III/VIII, B31.1/B31.3) • Practical, hands-on approach to problem-solving with a bias toward manufacturable, deployable designs over purely academic analysis • Excellent communication skills and a willingness to work collaboratively in a cross-functional, startup team environment