Lead Reactor Physicist / Core Design Lead (SMR / MMR Programs)

BaRupOn LLC • Irvine, CA

1d

About The Position

BaRupOn LLC is seeking a highly experienced Lead Reactor Physicist / Core Design Lead to own the reactor physics and core design program for its Small Modular Reactor (SMR) and Micro Modular Reactor (MMR) initiatives in the United States.
This is a technical leadership role at the heart of BaRupOn’s nuclear engineering organization. The Lead Reactor Physicist will be responsible for the full lifecycle of reactor core design — from initial neutronics modeling and fuel assembly optimization through safety analysis integration and NRC regulatory submissions. This person will work in close partnership with licensing, engineering, and operations teams to ensure every core design is safe, efficient, and fully compliant with applicable U.S. Nuclear Regulatory Commission (NRC) requirements.
The ideal candidate brings deep hands-on experience in reactor physics and core design for advanced or non-light water reactors, a strong command of U.S. nuclear regulatory frameworks, and the technical leadership ability to guide a growing team of physicists and engineers in a fast-paced, mission-driven environment.

Requirements

• Master’s or PhD in Nuclear Engineering, Reactor Physics, or a closely related field.
• 10+ years of experience in reactor physics, core design, or nuclear engineering within the U.S. nuclear industry.
• Proven, hands-on experience with reactor core design for SMR, advanced reactor, or Generation IV systems.
• Deep working knowledge of U.S. nuclear regulatory frameworks, including 10 CFR Part 50, Part 52, and the emerging Part 53 framework for advanced reactors.
• Demonstrated proficiency with industry-standard neutronics codes (e.g., MCNP, SCALE, CASMO, SIMULATE, or equivalent) and thermal-hydraulic modeling tools.
• Experience developing and validating computational methods and core simulation models for NRC licensing purposes.
• Strong technical communication skills, including the ability to author and defend regulatory documents and safety reports.

Nice To Haves

• Licensed Professional Engineer (PE) in the U.S. – preferred.
• Experience with NRC pre-application engagement and formal licensing interactions.
• Active membership in recognized nuclear professional organizations, such as the American Nuclear Society (ANS).
• Experience with advanced fuel cycle design, digital twin modeling, and integrated safety analysis software platforms.
• Familiarity with NEPA environmental review processes and modular construction design constraints.
• Strong mentoring, leadership, and cross-functional collaboration capabilities.

Responsibilities

• Lead the design, analysis, and optimization of SMR/MMR reactor cores, including fuel assembly configurations, control rod systems, and core loading strategies.
• Perform comprehensive reactor physics calculations: neutronics analysis, burnup and depletion modeling, reactivity control, flux distribution, and thermal-hydraulic integration.
• Develop, validate, and maintain core simulation models and analytical methods using industry-standard neutronics and thermal-hydraulic codes.
• Evaluate reactor core performance across the full range of operating and accident conditions, ensuring all safety margins are met.
• Ensure all core designs comply with NRC regulations, safety limits, and licensing requirements, including 10 CFR Part 50, Part 52, and the emerging Part 53 framework for advanced reactors.
• Support the development of Safety Analysis Reports (SAR/FSAR), technical specifications, and other regulatory documentation related to core design and reactor physics.
• Perform or oversee probabilistic risk assessments (PRA) and deterministic safety analyses in support of licensing submissions.
• Respond to NRC requests for additional information (RAIs) on core design and physics matters.
• Collaborate closely with the Director of Licensing & Regulatory Affairs, mechanical and structural engineers, and operations teams to integrate physics requirements into overall reactor system design.
• Provide physics input to thermal-hydraulic, structural, and materials engineering teams throughout the design process.
• Support project management on physics-related milestone planning, schedule dependencies, and technical risk identification.
• Guide, mentor, and develop a team of junior and mid-level reactor physicists and core design engineers.
• Establish and maintain core design standards, calculation methodologies, and code validation protocols across the team.
• Prepare and review technical reports, design certifications, and white papers for internal and regulatory audiences.
• Represent BaRupOn in technical forums, industry working groups, and national laboratory collaborations related to advanced reactor physics.

Benefits

• Take technical ownership of core design for one of the most ambitious SMR/MMR programs in the U.S. — from the ground up.
• Work directly alongside the CNO, CTO, and licensing leadership team with real authority over physics methodology and core design direction.
• Competitive compensation and benefits, including potential equity participation tied to program milestones.
• Collaborate with top-tier engineers, national laboratory partners, and federal program stakeholders at the frontier of advanced nuclear energy.
• A mission-driven company where technical excellence and safety culture are foundational, not aspirational.

What This Job Offers

• Job Type: Full-time
• Career Level: Mid Level
• Number of Employees: 1-10 employees