Principal Process Engineer, Fuel Cycle

About the role

You will own the end-to-end design and delivery of Helion's continuous fusion fuel cycle, translating complex process concepts into first-of-a-kind hardware that enables commercial fusion energy. This role requires you to define plant-level strategies, resolve multi-disciplinary tradeoffs, and ensure operability, scalability, and safety across all fuel cycle systems. You will serve as a hands-on technical authority, applying rigorous analysis and first-principles reasoning to dynamic, steady-state, and fault scenarios. You will mentor senior engineers, lead high-stakes design reviews, and represent Helion's fuel cycle architecture in external forums and industry engagements. You will collaborate closely with Engineering, Science, R&D, Operations, and Leadership to align on objectives and remove technical blockers. In this position, you will be accountable for delivering critical process systems from concept through integration, commissioning, and continuous improvement. You will report to the Fuel Cycle Manager and work onsite at our Everett, WA office.

Key facts

What you'll do

• Own delivery of major fuel cycle systems from concept through integration, including process design, procurement, installation, and commissioning, ensuring alignment with program timelines and technical objectives.
• Define plant-level fuel cycle philosophy and tradeoffs, including operational approach, throughput, energy usage, holdup inventories, and safety across fuel cycle systems to enable a scalable and efficient design.
• Utilize first-principles analysis, modeling, and rigorous simulation tools to evaluate steady-state, dynamic, and fault scenarios to ensure design operability, reliability, and performance under all conditions.
• Set technical direction for and guide detailed design of process equipment, including columns, reactors, membranes, heaters, exchangers, pumps, and piping, across ambient, high-temp, cryogenic, and vacuum conditions to meet functional and safety requirements.
• Develop and maintain core engineering design deliverables, such as process flow diagrams, piping and instrumentation diagrams, hazard and operability studies, and sizing calculations, ensuring technical rigor and consistency across the program.
• Drive cross-functional alignment across Science, R&D, EHS, Fuel Cycle Operations, and Plant Engineering to deliver a cohesive and scalable fuel cycle that integrates seamlessly with mission-critical systems.
• Lead high-level design reviews as the decision authority, resolving complex technical issues and ensuring alignment with program goals, system interfaces, and operational constraints.
• Ensure technical rigor and alignment of detailed engineering work across team process designs, including vacuum systems, cryogenic systems, reactors, separation columns, and associated support equipment.
• Mentor and develop senior engineers, establish engineering best practices, and shape team capability and technical standards to sustain long-term program execution and innovation.
• Represent Helion as a technical authority in external engagements, communicating fuel cycle architecture, design decisions, and program direction through industry forums, conferences, and publications to advance the fusion energy narrative.

Requirements

• Bachelor's or Master's degree in Chemical Engineering, Mechanical Engineering, Nuclear Engineering, or related field; advanced degree preferred as a demonstration of deep technical capability.
• 12+ years of experience in chemical process design, with a proven track record of translating process concepts into first-of-a-kind hardware that transitions from concept to execution.
• Deep technical expertise in transport phenomena (mass, heat, and momentum), thermodynamics, and reaction engineering applied to complex process systems that must perform reliably in demanding environments.
• Ability to decompose complex problems into fundamental physical principles, process objectives, and operational constraints to develop solutions grounded in first-principles reasoning and quantitative analysis.
• Demonstrated ownership of large-scale integrated systems, defining requirements, driving clarity in ambiguous problem spaces, and delivering robust solutions under significant technical and schedule pressure.
• Demonstrated accountability leading multi-disciplinary efforts and making system-level decisions that have significant program impact and influence cross-functional outcomes.
• Accountable as the technical authority for a technology domain, with expertise in relevant-to-fusion fuel cycle engineering, such as isotope separation, impurity separation, tritium handling, cryogenic systems, or vacuum systems, ensuring compliance and safety.
• Strong written and verbal communication skills to articulate technical rationale, design decisions, and program status to both technical and non-technical stakeholders within a fast-paced, high-visibility environment.
• Willingness to engage in hands-on problem-solving, including debugging during integration and commissioning, to resolve issues and validate that designs perform as intended in real-world conditions.
• Commitment to upholding Helion's values of urgency, rigor, ownership, and delivering hard truths, recognizing that these principles are essential to achieving unprecedented milestones in fusion energy development.

Nice to have

• Preferred items are aligned with the core requirements and demonstrate additional capability in fusion, advanced process systems, or technology-intensive industries, further strengthening your potential to contribute to Helion's mission.

Practical notes

This role is based onsite in Everett, Washington, and requires full-time engagement during standard business hours. Travel may be required for industry conferences, customer meetings, or facility visits as needed for program execution and external representation. Employment is contingent on authorization to work in the United States, and successful candidates must comply with all applicable employment eligibility verification requirements.