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SCALE is a comprehensive modeling and simulation suite for nuclear safety analysis and design developed and maintained by Oak Ridge National Laboratory under contract with the U.S. Nuclear Regulatory Commission, U.S. Department of Energy, and the National Nuclear Security Administration to perform reactor physics, criticality safety, radiation shielding, and spent fuel characterization for nuclear facilities and transportation/storage package designs.

The 8th SCALE Users’ Group Workshop (hybrid event) will be held June 5-7, 2024. Register here.

The SCALE 6.2.4 validation report four-volume set is now available on OSTI:

  1. SCALE 6.2.4: Validation Overview
  2. SCALE 6.2.4 Validation: Nuclear Criticality Safety
  3. SCALE 6.2.4 Validation: Reactor Physics
  4. SCALE 6.2.4 Validation: Radiation Shielding

The SCALE 6.3.0 validation reports will be released in 2023 with an additional volume specifically for spent fuel inventory and decay heat (Spent Fuel Applications) and additional Polaris and PARCS LWR validation in the Reactor Physics volume.

The SCALE 6.3 Online Manual is now available.

The SCALE 2024 Calendar is now available.

The SCALE website contains the following major sections:

  • Overview: additional details on SCALE capabilities.
  • Releases: details on SCALE releases.
  • Learning: information on upcoming in-person training courses at ORNL, SCALE primers, and learning modules that are based on our training courses experience.
  • References: links to downloadable scientific journal articles and reports with bibtex for easy citing of SCALE references. 
  • Support: how to get help with SCALE, including presentations, annual reports, newsletters, and QA documents.  

Please direct any inquiries to

For general SCALE references, please cite the latest manual.

W. A. Wieselquist, R. A. Lefebvre, Eds., SCALE 6.3.1 User Manual, ORNL/TM-SCALE-6.3.1, UT-Battelle, LLC, Oak Ridge National Laboratory, Oak Ridge, TN (2023). 

For more specific references see