Idaho National Laboratory is hiring a Senior Nuclear/Mechanical Thermal-Hydraulic Engineer. to work on our Thermal-Hydraulics Experiment and Modeling & Simulation team. Our team works a 9x80 schedule located out of our REC facility with every other Friday off. The individual will engage with senior INL leadership on critical issues that necessitate cross-organizational collaboration and will actively cultivate client relationships. The chosen candidate must have extensive experience in RELAP5-3D development and consistently stay informed about advancements in the nuclear and computing industries, proactively recommending code maintenance and development activities. Responsibilities Include: - Apply nuclear engineering principles to design, develop, test, and analyze nuclear equipment and systems. - Identifies and seeks new funding streams through industry contacts, writing white papers, and responding to RFPs (Request for Proposals). - Engages with current and prospective clients to add or modify existing capabilities within RELAP5-3D to meet client needs. Examines theory and coding to develop methods to implement required changes. - Leads assigned projects including, working collaboratively with team members to assign tasks, preparing budget estimates, developing project timelines and milestones, attending status meetings, and completing project presentations and reports. - Prepare the Software Design and Implementation Document (SDID) and conduct a design review for each project. - This posting ends: 9/12/25