Criticality Safety Engineer

About Aalo Atomics

Aalo Atomics is pioneering a new era in clean energy with factory-fabricated microreactors designed to deliver affordable, scalable, and reliable nuclear power. Our mission is to make nuclear energy globally accessible, starting with the Aalo-1, a 10 MWe reactor leveraging cutting-edge safety, modularity, and efficiency. Based in Austin, TX, we’re rapidly growing as we work to deploy the world’s first fleet of advanced microreactors. Join us and help revolutionize energy for a sustainable future.

About the Role

Aalo Atomics is seeking a Criticality Safety Engineer to support criticality safety analysis, design integration, and implementation activities for Aalo facilities. Working under the Lead Criticality Safety Engineer, you will develop technical evaluations, establish defensible limits and controls, and help engineering and operations translate criticality safety requirements into practical equipment designs and operating practices.

This role combines computational analysis with hands-on facility support. You will work with module owners, systems engineers, operations personnel, and specialists in nuclear safety, reactor physics, shielding, radiation protection, and spent fuel management. A central responsibility will be ensuring that analytical assumptions and criticality safety controls are reflected in designs, procedures, training, and actual operating conditions—not simply documented in an evaluation.

Assignments will reflect your experience and qualifications, with a defined path to develop facility-specific knowledge and broader criticality safety capabilities. Independent work and review authority will remain tied to completed qualifications.

Key Responsibilities

• Develop criticality safety evaluations and supporting calculations. Analyze fuel receipt, handling, assembly, storage, transfer, and other fissionable-material activities under normal and credible abnormal conditions. Document assumptions and methods and establish defensible subcritical limits and controls.
• Develop computational models and support method validation. Perform criticality calculations using MCNP, SCALE, or other validated tools. Support benchmark selection, validation, assessment of applicability, and determination of calculational bias, uncertainty, and appropriate margins. Maintain reproducible models and traceable calculation records.
• Establish practical criticality safety controls. Identify credible pathways to criticality and develop engineered and administrative controls consistent with applicable requirements and the double-contingency principle. Work with engineering and operations to ensure controls are clearly defined, verifiable, and appropriate to the activity.
• Integrate criticality safety requirements into facility and module designs. Interface with module teams based on their involvement in fissionable-material operations or potential effects on criticality safety. Identify cross-module interactions, translate analytical assumptions into design requirements, and review equipment and process designs for consistency with approved evaluations.
• Support control implementation at both facilities. Work with procedure owners and operations to incorporate criticality safety limits and controls into operating procedures, work instructions, inspections, surveillance activities, training, and postings. Develop and maintain control-implementation matrices, conduct field walkdowns, and support verification that controls are implemented before new or modified activities begin.
• Evaluate changes and support operational decisions. Review proposed facility modifications, equipment changes, procedures, tests, and new activities for criticality safety impacts. Coordinate with nuclear safety personnel when changes may affect the facility safety basis.
• Perform technical reviews and maintain analytical quality. Review evaluations, calculations, models, and supporting documents within your demonstrated competence and assigned authority. Provide independent review of work for which you did not have direct analytical responsibility, resolve review comments, and maintain clear, traceable technical records.
• Support criticality safety program implementation and facility readiness. Assist in developing and maintaining program documents, qualification materials, and training. Participate in assessments, readiness activities, corrective-action resolution, and preparation of criticality safety input to DOE submittals and responses to technical review comments.
• Coordinate with related technical disciplines. Work with nuclear safety, reactor physics, thermal-hydraulics, shielding, fire protection, and other specialists to maintain consistent assumptions and requirements. Provide criticality safety input to facility hazard analyses, safety-basis documents, and fresh- and spent-fuel management evaluations.

Required Qualifications

• Bachelor’s degree in nuclear engineering, physics, or a closely related engineering or scientific discipline.
• Demonstrated experience in nuclear criticality safety, including preparation or technical review of criticality safety evaluations and supporting calculations.
• Working knowledge of neutron physics, factors affecting criticality, and methods for evaluating fissionable-material operations under normal and credible abnormal conditions.
• Experience using MCNP, SCALE, or equivalent neutron transport tools for criticality analysis.
• Understanding of engineered and administrative controls, the double-contingency principle, and the relationship between analytical assumptions, design requirements, and operating limits.
• Familiarity with applicable ANSI/ANS-8 standards and criticality safety evaluation and validation practices.
• Ability to interpret engineering drawings, material specifications, system descriptions, and procedures and produce clear, technically defensible documentation.
• Strong communication and collaboration skills, including the ability to work directly with engineering and operations personnel, manage concurrent assignments, and raise safety concerns promptly.
• Ability to complete and maintain qualifications appropriate to assigned criticality safety responsibilities, including facility-specific knowledge and practical experience.

Preferred Qualifications

• Current or previous qualification as a Criticality Safety Engineer, including experience performing independent technical reviews.
• Experience with benchmark-based validation, determination of bias and uncertainty, establishment of upper subcritical limits, and assessment of benchmark applicability.
• Experience using the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Handbook or comparable benchmark resources.
• Familiarity with DOE-STD-3007, applicable provisions of NE O 420.1, and ANSI/ANS-8 standards addressing operational criticality safety, administrative practices, computational validation, and engineer qualification. Ability to distinguish requirements from guidance and apply the methods and editions adopted for each facility.
• Experience supporting DOE facility authorization, safety-basis interfaces, operational readiness reviews, or criticality safety program assessments.
• Direct experience implementing controls in procedures, developing implementation matrices, conducting field assessments, or supporting fuel handling and fresh- or spent-fuel storage.
• Familiarity with criticality accident alarm system applicability evaluations and criticality emergency planning interfaces.
• Proficiency in Python or other scripting tools used for model development, analysis automation, data processing, and quality checks.
• Experience using AI tools to improve the efficiency and effectiveness of engineering workflows.

What You Will Contribute

You will help connect criticality safety analysis to the equipment Aalo builds and the activities its personnel perform. Success in this role means producing defensible evaluations, identifying design and operational issues early, and helping teams implement clear, effective controls across both facilities. Your work will help ensure that fissionable-material operations remain safely subcritical and that criticality safety requirements are understood, maintained, and verified as designs and operations evolve.

Requirements: 

• Based in the United States
• Willing to work on-site in Austin, TX or Idaho Falls, Idaho

What We Offer:

• Competitive salary based on technical level
• Health, Dental, Vision Insurance
• Paid Time Off
• Corporate Gym Membership

Additional Information: 

Aalo Atomics provides a collaborative and supportive work environment, opportunities for professional growth, intellectually challenging careers, and competitive compensation. Aalo Atomics is an equal opportunity employer and considers all employment decisions without regard to race, color, religion, national or ethnic origin, sex, sexual orientation, gender identity or expression, age, disability, veteran status, or any other characteristic protected by law.

Applicants must be U.S. Citizens or U.S. Persons in compliance with 10 CFR Part 810 and may not hold non-compliant foreign citizenships.

Direct applicants only. No recruiters or staffing agencies, please.