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SNAP (Symbolic Nuclear Analysis Package)

The Symbolic Nuclear Analysis Package (SNAP) consists of a suite of integrated applications designed to simplify the process of performing engineering analysis. SNAP is built on the Common Application Framework for Engineering Analysis (CAFEAN) which provides a highly flexible framework for creating and editing input for engineering analysis software as well as extensive functionality for submitting, monitoring, and interacting with the software.  SNAP supports these various analytic software packages, along with a rich set of novel features, through a “plug-in” based architecture.  Each plug-in to SNAP is a self-contained “jar” file (java-archive file) that contains all the unique information necessary to interface with the respective software or feature.

 SNAP was conceived roughly twenty-five years ago by two of ISL’s retired employees, the late Ben Gitnick and his wife Terry.  The Gitnicks began pursuing a symbolic means of portraying the results of thermal hydraulic analyses in the late 1990s, writing the tool in C/C++.  Ken and Doreen Jones began developing SNAP in Java around the same time, foreseeing the robust maturation and widespread adoption of that programming language.  SNAP was then redesigned into the modern architecture used today, relying on the “core” functionality of CAFEAN to provide the application programming interface (API) for all SNAP plug-ins.  Government agencies, domestic commercial industry, and international organizations quickly adopted the Java-based SNAP model, which over the intervening twenty-five years has matured into the leading nuclear modelling, simulation, and digital-engineering tool due to the extraordinary technical talents of the SNAP development team and their dedication to quality, excellence, and accuracy.

This is an animation of a LBLOCA transient in RELAP5-3D modeled in SNAP. It shows the fluid conditions for the primary side of the system and the two steam generators after a pair of large breaks open in one of the loops of a Typical PWR model. This animation mask, and the associated TYPPWR RELAP5 input file are included with the SNAP RELAP5-3D plug-in. The movie was created with the SNAP Movie Generator.

Getting Started

A guide to downloading and installing SNAP and its prerequisite software.


Users’ manuals, on-line instruction, tutorials, and other SNAP related materials.

SNAP Plug-ins

Find information about the various SNAP plug-ins available to users.

Technical Support

Technical support is available to CAMP members, NRC contractors and SNAP User’s Group members.

On-line Training Videos

This is a series of short on-line videos hosted on ISL’s YouTube Channel covering a range of introductory items from an overview of the SNAP User Interface to Job Stream submission.