Recent News
SNAP Version 4.1.4 Released
August 10, 2023
AptPlot 8.0.3 Updated
May 22, 2023
PyPost 4.0.3 Released
August 18, 2022

SNAP User's Group

The SNAP User's Group (SUG) was formed in 2013. The mission of this User's Group is to promote the use and development of new SNAP plug-ins and utility applications. Software developed under funding from the User's Group will be available to all members of the group. SUG members have access to additional plug-ins that are not funded by the NRC. These include:

Full featured RELAP5/RELAP5-3D Plug-In:

The RELAP5-3D plug-in adds support for the additional inputs that are provided by the RELAP5-3D analysis in versions 2.2, 2.3, 2.4, and 2.6. This support applies to the graphical editing features provided by the ModelEditor as well as ASCII import/export. It also includes custom Job Stream support for the RELAP5-3D executable's command line parameters and license file requirements.

Advanced Restart Editing

RELAP5 restart decks are represented in the ModelEditor by "Restart Cases" that also include the following features. This version of the plug-in supports Graphical Editing and Initial Condition Set Selection for resart cases.

Editing a case graphically opens the case as a Virtual Model in the Modeleditor. The ModelEditor tracks any changes made to the model in this mode and colors the modified components red in the Navigator. Once the changes have been made they can be saved back into the Restart Case as a restart input deck by pressing the Save button or discarded by pressing the Close button.

The RELAP5 plug-in provides the ability to import initial conditions from previously completed jobs and store these conditions as Initial Condition Sets within the model. The RELAP5-3D plug-in extends this capability by allowing an initial condition set to be selected for each restart case. The selected initial conditions will be applied to the restart case automatically when submitting a Job Stream.

Unix Substitution Variable Support

This feature allows user defined numerics whose names start with a dollar ($) be included in the restart case by name instead of by numeric value. This is used, for example, to create template models with parameters that are substituted at runtime with values from some external data source.
This feature is supported for ASCII Import, ASCII Export, Restart Case, and Job Stream submit (plug-in version 4.3.1+).

Attribute Level Ownership and Reviewing

Ownership Data can be associated with each property and includes the owner, last modified time, reviewer, and last reviewed time. The user who last modified a property is its owner. When a property is modified the current user becomes the owner, the last modified time is set, and the reviewer/last reviewed time are discarded. Attributes can be Reviewed in the Review Properties window. This window includes a table of every attribute in the model along with its component, attribute group, and owner/reviewer. To review an attribute, select it in the table and press the Review button on the toolbar.

Parametric Model Export

The Job Stream system provides the capability to create parametric models and use them to run RELAP5 jobs on a local or remote Calculation Server, as well as on remote High Performance Computing systems. The Parametric Model Export feature provides similar parametric capability for a single RELAP5 model without the job submission process. This is useful in situations where the jobs must be run on the command line for some system-specific reason.

Model Notebook Export

The RELAP5-3D plug-in supports the generation of model-wide reports as a single annotated document called a "Model Notebook". Information such as calculations, export data, model status, attribute descriptions, etc. are all included.

3D Model Visualization and Coordinate Generation

RELAP5 components may be modeled in 3D coordinate space. The actual three-dimensional layout of a model can be viewed and modified using the 3D viewer built into the SNAP plug-in for RELAP5. 1D component models may also be displayed in 3D, however, the initial component locations must first be generated.
The 3D coordinate generation tool allows initial 3D locations to be generated from the existing elevation data. This tool requires the user to select a component for each hydraulic loop and an X/Y offset for that component. It then loops through all the hydraulic components placing them adjacent to one another in a chain.

Sub-System Import/Export

The sub-system integrator (or "Master Integrator") allows a sub-system in one model to be imported into another model. Once imported, the integrator can also be used to update the imported sub-system without requiring the components to be reconnected manually.
For example, a standalone steam generator model could be created with all of the necessary boundary conditions to run to a steady state. The hydraulic components and heat structures that make up the steam generator can then be added to an Exportable sub-system. This sub-system could then be imported into a full plant model and connected to the appropriate locations. Later, when changes are made to the steam generator model, the full plant model can be updated to include these changes. All of the connections made in the full plant model will be automatically reconnected.

SNAP-MATLAB Interface:

This interface provides the ability to access plot data generated by the TRACE, COBRA-IE, RELAP5 and MELCOR codes directly from MATLAB programs.


SUG members will recieve periodic distributions of SNAP and APTPLOT on CD. Please note that NRC approval is still required to obtain SNAP distributions.

User's Group Memberships are available at the annual cost of $5,000 per site. For further information, please contact:

Administrative Point of Contact:
Clara Anderson, CPCM, PMP, LSSBB
Director of Contracts
Phone: (757) 298-8920

Technical Point of Contact:
Don Ulshafer, Jr.