NRC SFST ISG-21: USE OF COMPUTATIONAL MODELING SOFTWARE

Given the growing industry need to store spent reactor fuel of increasingly higher burnups and
heat loads in dry storage casks, and eventually to transport that same spent fuel in
transportation packages, analyzing the performance of casks and other radioactive material
packages has become a greater challenge. Finite Element, Finite Difference, and Finite
Volume analysis computer codes, defined here as Computational Modeling Software (CMS),
are tools used by many licensees to analyze cask and package performance in the structural
and thermal disciplines. CMS can be used to determine structural stresses, dynamic impact or
drop performance, and thermal performance of cask designs.
The information in this Interim Staff Guidance (ISG) will supplement the guidance provided in
the Standard Review Plans (SRPs) for Dry Storage Facilities and Storage and Transportation
Cask and Package reviews.
Similar guidance on the use of CMS in the criticality and shielding disciplines can be found in
NUREG/CR-5661, “Recommendations for Preparing the Criticality Safety Evaluation of
Transportation Packages,” and NUREG/CR-6802, “Recommendations for Shielding Evaluations
for Transport and Storage Packages.”