Nuclear Criticality Safety Engineer

Nano Nuclear Energy, Inc.; Oak Ridge (TN); On-site; USD 145,000 - 180,000; Full time

Benefits offered by this job

Hybrid work

Relocation assistance

Medical insurance

Dental insurance

401(k) match

Unlimited PTO

Job summary

NANO Nuclear Energy, Inc. in Oak Ridge, TN is seeking a senior criticality safety engineer to Own the criticality safety basis for the KRONOS MMR fuel lifecycle.

You will establish and defend safety basis across fresh and irradiated fuel handling, transportation, storage, and qualification activities. This role involves cross-functional collaboration with fuel design, performance, transportation, and QA teams to ensure configurations remain inherently safe and compliant with NRC requirements,

Qualifications

• Degree in Nuclear Engineering, Physics, or a related highly technical discipline.
• 5+ years of nuclear criticality safety experience, including authorship and independent defense of evaluations involving fissile-material processing, laboratories, storage, or transportation.
• Proficiency with industry-standard criticality safety codes such as MCNP and SCALE/KENO.
• Demonstrated experience establishing code validation, benchmark applicability, calculational bias and uncertainty, and subcritical margins using recognized critical experiments and sensitivity/similarity methods.
• Working knowledge of applicable ANSI/ANS-8 standards, double-contingency principles, criticality alarm and emergency-planning interfaces, and engineered and administrative controls.

Responsibilities

• Execute criticality safety analyses for fresh and irradiated fuel movement, including reactor-site transportation and inter-facility transfers.
• Define and validate geometric and moderation constraints for fresh-fuel and spent-fuel storage configurations.
• Model credible accident scenarios, including inadvertent moderation and geometric reconfiguration during handling events.
• Establish preventive and mitigative controls that maintain required subcritical margins.
• Partner with fuel design, fuel performance, and transportation teams to ensure handling equipment and transport casks maintain inherently safe configurations.
• Develop configuration-controlled criticality evaluations, validation reports, calculation packages, and operational limits in accordance with ASME NQA-1 and NRC requirements.
• Define and approve the criticality safety basis for HALEU-bearing qualification materials, fuel lots, test specimens, fabrication activities, packaging, shipments, irradiation support, PIE handling, and waste or residue disposition.

Skills

Criticality safety

Nuclear engineering

Code validation & benchmark

Regulatory compliance

Education

Bachelor's degree in Nuclear Engineering or Physics

Tools

MCNP

SCALE/KENO

Job description

Oak Ridge, TN | $145K–$180K | Hybrid | Relocation Assistance Available

Own the Criticality Safety Basis for Advanced Nuclear Fuel

The Opportunity

Take ownership of criticality safety for the fuel lifecycle of the KRONOS MMR, a High-Temperature Gas-Cooled Reactor (HTGR) fueled by ceramic matrix TRISO fuel.

This role goes beyond performing individual calculations. You’ll establish and defend the criticality safety basis for out-of-core fuel operations spanning fresh and irradiated fuel handling, transportation, storage, qualification materials, test specimens, irradiation support, PIE activities, and material disposition.

Reporting jointly to the Reactor Fuel Design Manager and Reactor Design Manager, you’ll work across fuel design, performance, transportation, and qualification programs to ensure inherently safe configurations and rigorous nuclear quality standards.

Why This Opportunity Stands Out

• Own criticality safety analysis across handling, transportation, storage and qualification activities.
• Work directly with HALEU, TRISO fuel, graphite and ceramic moderation, and HTGR fuel configurations.
• Influence both fuel design and reactor design through a highly cross-functional role.
• Establish safety limits and controls for credible accident and upset scenarios.
• Apply advanced criticality methods using MCNP, SCALE/KENO, benchmark validation, bias and uncertainty, and sensitivity/similarity methods.
• Build qualification-grade safety documentation under rigorous NRC and nuclear QA requirements.

What You’ll Do

• Execute criticality safety analyses for fresh and irradiated fuel movement, including reactor-site transportation and inter-facility transfers.
• Define and validate geometric and moderation constraints for fresh-fuel and spent-fuel storage configurations.
• Model credible accident scenarios, including inadvertent moderation and geometric reconfiguration during handling events.
• Establish preventive and mitigative controls that maintain required subcritical margins.
• Partner with fuel design, fuel performance, and transportation teams to ensure handling equipment and transport casks maintain inherently safe configurations.
• Develop configuration-controlled criticality evaluations, validation reports, calculation packages, and operational limits in accordance with ASME NQA-1 and NRC requirements.
• Define and approve the criticality safety basis for HALEU-bearing qualification materials, fuel lots, test specimens, fabrication activities, packaging, shipments, irradiation support, PIE handling, and waste or residue disposition.

What You’ll Bring

Required Qualifications

• Degree in Nuclear Engineering, Physics, or a related highly technical discipline.
• 5+ years of nuclear criticality safety experience, including authorship and independent defense of evaluations involving fissile-material processing, laboratories, storage, or transportation.
• Proficiency with industry-standard criticality safety codes such as MCNP and SCALE/KENO.
• Demonstrated experience establishing code validation, benchmark applicability, calculational bias and uncertainty, and subcritical margins using recognized critical experiments and sensitivity/similarity methods.
• Working knowledge of applicable ANSI/ANS-8 standards, double-contingency principles, criticality alarm and emergency-planning interfaces, and engineered and administrative controls.
• Experience analyzing enriched uranium and heterogeneous fuel configurations involving powders or kernels, TRISO particles, graphite or ceramic moderation, arrays, reflection, interaction, and credible upset conditions.
• Experience developing configuration-controlled evaluations and calculation packages under ASME NQA-1, 10 CFR Part 50 Appendix B, DOE, or equivalent nuclear software-quality requirements.

Preferred Qualifications

• Direct experience with TRISO-based fuels, HALEU, or graphite-moderated fuel elements.
• Experience coordinating with transportation, security, or logistics partners on nuclear material movement.
• Familiarity with criticality safety considerations associated with refueling operations.

Compensation & Benefits

• Base Salary: $145K–$160K, depending on experience
• Hybrid work environment
• Relocation assistance available
• Medical, dental, vision, and life insurance with company contributions
• 401(k) match up to 5%
• Unlimited PTO
• Company holidays and paid parental leave
• Opportunities for continued professional growth

Interested in Taking Greater Ownership of Criticality Safety?

If you’re an experienced criticality safety engineer looking to apply your expertise to HALEU, TRISO fuel, advanced reactor development, and complex fuel qualification activities, we encourage you to

NANO Nuclear Energy is an equal opportunity employer committed to fostering a diverse and inclusive workplace. We encourage individuals with diverse backgrounds, experiences, and perspectives to apply.