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SCALE (previous version)

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.

SCALE 6.2.4 Update

SCALE 6.2.4 is available to update your existing SCALE 6.2.0, 6.2.1, 6.2.2, or 6.2.3 installation. SCALE 6.2.4 provides only maintenance and fixes described below. SCALE 6.2.4 incorporates all updates made since the SCALE 6.2.0 release so that users can proceed directly to the SCALE 6.2.4 update, even if previous updates have not been applied.

Fixes in SCALE 6.2.4 are summarized below, with additional details available here.

  • An issue was identified in SCALE versions 6.2.0-6.2.3 and fixed in SCALE 6.2.4 where the Standard Composition Library (STDCOMP) and related functions did not include an input check that certain elements must have user-defined isotopics. The elements listed in Table 7.2.2 have natural abundances which define a default isotopic distribution. Elements not listed in table include Tc, Pm, Po, At, Fr, Ac, Pa, and all actinides with atomic numbers greater than 92 (Np, Pu, Am, Cm, Bk, Cf, Es, etc.). For these elements, which are referred to as non-naturally occurring elements, the isotopic distribution is strongly dependent on the production source and decay time of the material, and the user is required to enter isotopic distributions for these elements or to simply enter the isotopic number densities directly. In SCALE versions 6.2.0-6.2.3, this check was not operating as intended.
  • An issue has been fixed in SCALE 6.2.4 where DBRC data was not being correctly loaded on Windows in 6.2.3, and with the DBR=2 option there was no indication that the data was not loaded and the calculation proceeded without warning.
  • An issue has been fixed in SCALE 6.2.4 where including a thermal moderator nuclide (e.g., H-1) at multiple temperatures in the input was not handled correctly. This issue was introduced in 6.2.2 and affects both TRITON and CSAS calculations which utilize KENO as the transport solver.
  • An issue has been fixed in SCALE 6.2.4 where in ORIGEN calculation of (alpha,n) sources for 10 million years decay, ORIGEN did not include Am-241 in the results. This issue was due to floating point comparisons applied to the final time isotopics where very little Am-241 was left, leaving out Am-241 in early times.
  • An issue has been fixed in SCALE 6.2.4 where ORIGAMI did not allow some valid power histories which occur when one wants to model a fine-grained power history with no intermittent decay.
  • An issue with the TRITON swap capability has been fixed in SCALE 6.2.4, where the TRITON swap capability did not function correctly in many scenarios. The extent of the error was not fully categorized but the error is due to incorrect bookkeeping of the volume of mixtures involved in the swap. All users of the TRION swap capability are encouraged to update to 6.2.4.

  • An issue was fixed in SCALE 6.2.4 where MAVRIC could not perform CE responses for nu-fission. The nu-fission reaction (mt=1452) is useful as a response and is supported for MG simulations. However, this reaction is not present in CE libraries directly; rather it is calculated as a multiplication of nu-bar (mt=452) and σf  (mt=18) fission cross sections during the response generation. MAVRIC CE responses for the nu-fission reaction are now enabled in 6.2.4.

To request the SCALE 6.2.4 update, please email us at

To view the previous SCALE Updates, please click here.

SCALE User Notice - March 8, 2018

Read the Fiscal Year 2018 Report on SCALE Maintenance and Development