Senior Nuclear Criticality Safety Engineer

X-energy; Oak Ridge (TN); On-site; USD 93,000 - 186,000; Full time

Benefits offered by this job

401K with employer match

Medical/Dental/Vision insurance

Life and Disability Insurance

Paid Time Off

Tuition Reimbursement/Professional Dev

Job summary

X Energy, LLC in Oak Ridge, TN, seeks a Nuclear Criticality Safety Engineer to ensure safe handling of fissile materials and NRC compliance across TRISO-X operations. The role spans design support through daily operations and involves developing safety basis evaluations and ISA support.

You will perform NCS calculations, lead Process Hazards Analysis activities, train staff, and mentor Level II–IV engineers while advancing ISA documentation and safety controls.

Qualifications

• Bachelor’s degree in a STEM field from ABET-accredited college/university.
• Level II: ~3+ years in nuclear criticality safety with safety basis evaluations.
• Experience using SCALE/MCNP or similar NCS codes to demonstrate subcriticality.
• Ability to qualify under ANSI/ANS-8.26-2007 training program.
• Level III: ~5+ years in NCS with safety basis evaluations.
• Level IV: ~10+ years in NCS; ISA Risk Assessments & Process Hazards analysis lead.
• Experience with regulatory requirements, standards, and guidance.

Responsibilities

• Define safety basis for fissile material operations; monitor IROFS, limits, controls and barriers.
• Develop/review NCS evaluations to demonstrate subcriticality for processes and facility operations.
• Develop/review calculations using NCS codes and models.
• Lead/participate in Process Hazards Analysis with multidisciplinary teams.
• Evaluate accident sequences and ISA risk assessments; identify IROFS.
• Advise operations on NCS impacts of changes to processes and facility designs.
• Participate in design reviews; conduct surveillances and audits.
• Develop/revise NCS training and postings for administrative controls.
• Support the emergency response team.

Skills

Subcriticality analyses

NCS guidance

Hazard analysis

Education

ABET-accredited STEM degree

Tools

SCALE

MCNP

Job description

X Energy, LLC in Oak Ridge, TN, seeks a Nuclear Criticality Safety Engineer to ensure safe handling of fissile materials and NRC compliance across TRISO-X operations. The role spans design support through daily operations and involves developing safety basis evaluations and ISA support.

You will perform NCS calculations, lead Process Hazards Analysis activities, train staff, and mentor Level II–IV engineers while advancing ISA documentation and safety controls.