Thermal-Hydraulics and Safety Analysis Engineer - Isotopes

Oklo Inc. develops advanced fission power plants, domestic radioisotope production, and nuclear fuel recycling technologies. The Thermal-Hydraulics and Safety Analysis Engineer will own systems-level thermal-hydraulic safety analyses for isotope production facilities, supporting reactor design, safety cases, and licensing. The role includes transient modeling, safety-methodology development, uncertainty assessment, technical documentation, and collaboration across engineering and licensing teams.

Responsibilities:

• Develop, maintain, and execute systems-level thermal-hydraulic models of reactor and plant behavior using RELAP5 or comparable analysis codes
• Analyze normal operating conditions, anticipated operational occurrences, design-basis events, and selected beyond-design-basis conditions relevant to the thermal-hydraulic safety case
• Develop event-specific analysis plans, including initial and boundary conditions, assumptions, acceptance criteria, figures of merit, and treatment of uncertainties
• Develop and document thermal-hydraulic safety-analysis methods, modeling guidance, and engineering practices appropriate to advanced reactor licensing
• Establish and justify code, model, and correlation applicability for the physical phenomena and operating regimes being evaluated
• Perform model verification, validation, sensitivity studies, uncertainty analyses, scaling evaluations, and comparisons with experiments, benchmarks, hand calculations, or higher-fidelity analyses. Identify gaps in available methods, data, and validation evidence, and define practical plans to close those gaps
• Translate regulatory requirements and safety acceptance criteria into defensible analysis requirements and technical evaluation strategies
• Prepare high-quality calculation packages, methodology documents, safety-analysis reports, licensing-application content, and responses to regulator questions
• Evaluate design changes and provide timely feedback on their effects on transient response, safety margins, system performance, and the licensing basis
• Collaborate with reactor physics, fuel, controls, mechanical, thermal-hydraulics, safety, and licensing engineers on coupled analyses and interface conditions
• Develop scripts and automated workflows for model generation, execution, post-processing, regression testing, and configuration control
• Review safety analyses and models prepared by internal contributors, vendors, and external partners

Requirements:

• • Bachelor's, master's, or doctoral degree in nuclear, mechanical, chemical, or aerospace engineering, or a closely related technical field
• • Five or more years of relevant experience in reactor thermal-hydraulics, nuclear safety analysis, reactor transient analysis, or a closely related field
• A relevant advanced degree may substitute for a portion of the professional experience
• • Demonstrated experience developing and executing systems-level transient models using RELAP5
• • Strong foundation in heat transfer, fluid mechanics, thermodynamics, and reactor thermal-hydraulics
• • Experience defining and analyzing reactor transients or accident scenarios, including initial conditions, boundary conditions, equipment response, operator or control actions, and acceptance criteria
• • Experience evaluating the reasonableness and applicability of models, correlations, assumptions, and results rather than treating analysis software as a black box
• • Experience documenting engineering analyses in clear, reviewable technical reports or calculation packages
• • Ability to work independently while collaborating effectively across engineering and licensing disciplines
• • Experience with verification and validation, uncertainty quantification, sensitivity analysis, scaling, bias evaluation, or code applicability assessments
• • Familiarity with experiment design, separate-effects and integral-effects testing, benchmark problems, and the use of test data to validate analytical methods
• • Skilled at developing and interpreting systems-level reactor transient analyses
• • Able to connect thermal-hydraulic behavior, safety functions, acceptance criteria, and licensing conclusions
• • Methodical about verification, validation, uncertainty, configuration control, and technical documentation
• • Comfortable making conservative but technically defensible assumptions when information is incomplete
• • Able to distinguish important safety drivers from modeling detail that does not materially affect a conclusion
• • Comfortable explaining model limitations and uncertainty to designers, reviewers, and regulators
• • Collaborative and effective at working across safety, licensing, design, reactor physics, and analysis teams
• • Willing and able to learn quickly, think differently, and do things in new ways
• • Comfortable in a fast-paced, highly iterative startup environment
• • An excellent writer who can write in a modern active voice, and able to communicate technical content and results verbally
• • Experience supporting NRC or DOE licensing applications, audits, topical or methodology reports, requests for additional information, or other regulatory interactions
• • Fluency with Python or another language used for model automation, data analysis, visualization, and quality checks
• • Competency with modern software engineering practices, including version control, automated testing, reproducible computing environments, and continuous integration
• • Experience working under a nuclear quality-assurance program or with safety-related analysis software and records
• • Experience mentoring other analysts or providing technical review of safety-analysis work