The U.S. Nuclear Regulatory Commission (NRC) uses the computer code Fuel Analysis under
Steady-state and Transients (FAST) to model steady-state and transient fuel behavior to support
regulatory decisions. FAST relies on a material properties library (MatLib) that contains the
thermal and mechanical properties of the nuclear materials and coolants of interest to support the
US commercial nuclear industry. MatLib contains properties for a variety of nuclear fuels, cladding
and other structural materials, gases, and coolants.
In this document, material property correlations for the materials contained within MatLib are pre-
sented and discussed. When available, comparisons are made between the material property
correlations and available data. Additionally, uncertainties are quantified on the material proper-
ties, which is then used by the NRC to support uncertainty quantification for best-estimate plus
uncertainty safety evaluation reviews.
This document describes MatLib-1.2, which was updated from MatLib-1.1 to include cleanup of the
code for streamlined calls to MatLib from the main FAST source code, and to enable easier
readability of the code by developers that maintain and enhance the FAST code. The results of
MatLib did not change between MatLib-1.1 and MatLib-1.2; however, the source code changes warranted
incrementing the minor numbering of the software version number. The changes may result in faster
execution times of FAST-1.2 as compared to FAST-1.1.
This document is one of a series of documents on FAST; the other documents detail the models
used by FAST as well as its integral assessment to experiments and commercial data.