Ensuring nuclear criticality safety throughout the fuel cycle—today and tomorrow.
ORNL’s Criticality Safety Analysis & Research (CSAR) group develops and applies the methods, models, and guidance necessary to promote and maintain nuclear criticality safety.
Nuclear energy is a cornerstone of American power production, and advanced reactors, higher-enrichment fuels, and new fuel types are expanding what nuclear can deliver. The backbone that keeps this progress smooth and dependable is nuclear criticality safety—ensuring nuclear research and operations can proceed efficiently and confidently.
Working alongside DOE sponsors and industry, CSAR strengthens analysis methods, streamlines reviews, and maintains the trusted tools that underpin the safe handling, transportation, and storage of fissile materials.
Trusted tools, methods, and data
The CSAR team’s leverages a multidisciplinary skillset to address nuclear criticality safety challenges. These core capabilities include:
- Shielding and transport analysis: Performing high-fidelity neutral-particle transport and dose/shielding evaluations that support safe handling, storage, and transportation of fissile materials.
- Sensitivity/uncertainty (S/U) analysis: Developing, maintaining, and applying S/U analysis capabilities to targets validation gaps and data needs.
- Benchmarking and validation: Using application-specific validation suites to test novel fuel forms and reactor designs. These validation efforts provide indispensable data for the engineering of advanced reactor systems.
- CSAR is a primary contributor to the development of SCALE and uses the code suite for criticality safety analyses, reactor physics, radiation shielding, radioactive source term characterization, and sensitivity.
Collaborations that accelerate impact
CSAR works closely with the Department of Energy, Nuclear Regulatory Commission, and the DOE Nuclear Criticality Safety Program, as well as numerous industry partners to enhance the reliability, safety, and economics of the nuclear energy sector. Current collaborations span several areas, including:
- Designing and evaluating subcritical and critical measurements that close key validation gaps.
- Supporting regulatory and industry partners with reliable analyses for licensing and compliance.
- Translating experimental outcomes into benchmarks and validation tools used throughout the nuclear safety community.
- Contributing as principal investigators, analysts, and reviewers on national and international projects.
- Providing leadership in working groups that establish and disseminate best practices in criticality safety.
Recent accomplishments
The CSAR team’s recent technical achievements are supporting nuclear criticality safety through contributions to leading databases and codes:
- Expanded benchmarking models and improved validation workflows in SCALE that strengthen analyses for HALEU and advanced fuels.
- Completed benchmarking of the ORNL Health Physics Research Reactor (HPRR) shielding experiment evaluation for inclusion in the Shielding Integral Benchmark Archive Database, or SINBAD.
- Resolved known defects in the Verification and Data Evaluation Repository (VADER), supporting more reliable validation pipelines through model and code quality improvements.
- Forthcoming contributions to upcoming Nuclear Regulatory Commission publications technical reports, as well as new integral experiment design efforts under the DOE/NRC Collaboration for Criticality Safety Support for Commercial-Scale HALEU Fuel Cycles and Transportation and the DOE Nuclear Criticality Safety Program will close priority validation gaps.
Looking ahead
Driven by a core culture of operational safety, the Criticality Safety Analysis & Research Group works to prevent unintended criticality incidents. By refining analysis methods, maintaining trusted tools, and contributing to benchmark experiments and guidance, CSAR provides the foundation that allows nuclear research and deployment to proceed smoothly and safely.
As nuclear energy expands to meet future needs, CSAR’s expertise will continue to anchor reliable, efficient, and responsible progress across the fuel cycle.