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Senior Nuclear Safety Criticality Engineer

Remote

At Lightbridge, we’re pioneering advanced nuclear fuel technology that’s designed to make reactors safer, more efficient, and more responsive to global energy needs. Our mission is bold and we’re looking for equally bold thinkers to help us bring it to life. If you thrive at the intersection of engineering and regulatory strategy, this is your opportunity to help shape the future of clean energy.

Overview

The Senior Nuclear Criticality Safety Engineer provides technical leadership and oversight for criticality safety across HALEU fuel manufacturing, transportation, storage, and handling operations supporting light water reactor (LWR) applications. This role is responsible for developing, reviewing, and approving complex nuclear criticality safety evaluations (NCSEs), establishing robust safety controls for higher enrichment systems (up to 20 wt% 235U) and ensuring compliance with NRC and/or DOE regulatory frameworks.   The position requires deep expertise in neutron physics, fuel cycle operations, and validated computational methods, along with the ability to mentor junior engineers and interface effectively with operations, licensing, and design teams.

Responsibilities:

  • Lead, perform, and approve nuclear criticality safety evaluations (NCSEs) for fuel fabrication, handling, storage, and transportation processes.
  • Establish and validate criticality safety limits and engineered/administrative controls addressing mass, moderation, geometry, reflection, enrichment, and interaction for HALEU systems.
  • Lead method qualification and validation activities, including code verification, benchmark selection, trending analysis, and documentation under software quality assurance (SQA) programs.
  • Apply validated neutronics methods and tools (e.g., Monte Carlo codes such as MCNP, SCALE/KENO) to assess , margins to criticality, and bias/uncertainty.
  • Support the development and maintenance of the Criticality Safety Program in accordance with ANSI/ANS-8 standards and applicable NRC/DOE regulations.
  • Prepare and review technical documentation, including safety analyses, calculation packages, and safety evaluation reports.
  • Interface with operations personnel to ensure proper implementation of controls and provide technical guidance during process changes.
  • Participate in hazard analyses, process design reviews, and configuration management activities.
  • Conduct criticality safety training for plant personnel and support emergency preparedness activities related to criticality incidents.
  • Support licensing activities, including preparation and review of safety basis documents, and responses to NRC Requests for Additional Information (RAIs).
  • Support internal and external audits, regulatory inspections, and corrective action programs.
  • Perform or participate in surveillance, inspections, walkthroughs, appraisals, or audits of fissile material operations to ensure compliance with Nuclear Criticality Safety Approvals, Nuclear Safety rules, including Safety Analysis Reports, Safety Assessments, Safety Reviews, and risk assessments/analyses.
  • Mentor and technically direct junior engineers; perform independent technical reviews and approvals of criticality safety analyses.

Required Experience:

  • Bachelor’s degree in Nuclear Engineering or a closely related discipline (Master’s or Ph.D. preferred).
  • Minimum of 8 years of experience in nuclear criticality safety, or reactor physics.
  • Demonstrated experience leading complex NCSEs and establishing criticality safety controls in regulated nuclear facilities.
  • Proficiency with neutronics analysis tools such as MCNP, SCALE, or equivalent.
  • Strong understanding of neutron physics, cross-section data, and bias/uncertainty methodologies.
  • Familiarity with ANSI/ANS-8 standards, NRC regulations (10 CFR 70/71), and/or DOE criticality safety requirements.
  • Experience developing and applying bias and uncertainty methodologies and establishing USLs.
  • Ability to interpret engineering drawings, process flow diagrams, and material specifications.
  • Proven ability to lead technical reviews, mentor staff, and interface with regulators and senior stakeholders.

Preferred Qualification: 

  • Experience in nuclear fuel fabrication or fuel cycle facilities.
  • Experience with uranium metal/alloy processing (as opposed to oxide fuel forms), including handling of enriched uranium in metallic form.
  • Experience with HALEU-specific criticality considerations
  • Knowledge of burnable absorbers, enrichment limits, and fuel assembly design considerations.
  • Experience with software quality assurance (SQA) and code validation practices.
  • Prior involvement in facility startup, licensing, or readiness review activities.

Lightbridge is committed to supporting the people who power our mission. We offer a comprehensive, competitive benefits program designed to promote well‑being, flexibility, and long‑term growth, including:

•     Competitive salary and performance bonuses, including cash and equity awards
•     Remote‑first work culture with opportunities for travel
•     100% company‑paid health, dental, and vision coverage
•     401(k) with 100% company match
•     Generous time off and family care benefits
•     Up to 32 hours per year of company‑covered professional development course fees


If you’re excited about contributing to work that will help shape the future of clean energy, we encourage you to apply. We look forward to learning more about you and the impact you can make at Lightbridge.

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