.. _section-1.2:

SAS4A/SASSYS‑1 Version 5
------------------------

In the time since the development of Version 3, several modeling
additions and enhancements have been made to meet U.S. Department of
Energy programmatic needs. Significant among these are

-  Detailed sub-channel models for whole-core analyses to resolve
   intra-assembly temperature and flow distributions [1‑9]

-  3D visualization capabilities for sub-channel results.

-  Extended decay-heat models to support long-term transients and
   complex, actinide-bearing fuels.

-  Support for coupling with external CFD simulations to resolve flow
   distribution and thermal stratification effects.

-  Treatment of axial expansion feedback from assembly duct walls

-  Support for spatial kinetics (requires DIF3D-K)

-  Extension of the control-system model to include sinusoidal functions
   that can be used to represent seismic oscillation effects.

-  Addition for heavy liquid-metal coolants (lead and lead-bismuth
   eutectic)

-  Support for user-defined coolant properties

-  Detailed steam-generator model updates

-  New electromagnetic pump modeling capabilities

-  Several bug fixes and other enhancements

In addition to the above, a major restructuring of the code has been
completed to adapt all source files to free-form source format and new
model developments are being implemented using modern object-oriented
practices.