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Frequently Asked Questions (FAQ) - SNAP/RADTRAD


1. What type of computer do I need to run SNAP/RADTRAD?
SNAP/RADTRAD is designed to be platform independent, pure-Java, plug-in architecture, which can be installed on any computer and operating system. SNAP is easily installed on any system that has a Java 7.0 or later JRE. The software is packaged in APT's Java installation software which simplifies the installation process and provides platform specific launchers for Java applications.


2. How much computer disk space does SNAP/RADTRAD need to install?
The SNAP/RADTRAD software (including the RADTRAD-AC) installation requires about 300 MB of disk space. The plotting tools software package, AptPlot, installation requires about 190 MB of disk space.


3. Will SNAP/RADTRAD run on a Mac or MacBook Pro?
Yes, SNAP/RADTRAD is designed to be platform independent, pure-Java, plug-in architecture, which can be installed on any system that has a Java 7.0 or later JRE. The software is packaged in APT's Java installation software which simplifies the installation process and provides platform specific launchers for Java applications.


4. What do I do if I can’t get SNAP/RADTRAD to install correctly?
Verify that installation directions on the APT “Download SNAP” (https://www.snaphome.com/snap/regAccess/download.jsp) website and in Section 2.3 or the SNAP/RADTRAD User’s Guide, located at the “Download the SNAP/RADTRAD User’s Guide,” were correctly followed. If the installation error still persists then:


1. What is the latest version of the RADTRAD software?
The latest version of this software is SNAP/RADTRAD 4.0 which was released by the U.S. NRC on December 31, 2014. This version of the code consists of three parts which are the RADTRAD Analytical Code (RADTRAD-AC) the Symbolic Nuclear Analysis Package (SNAP) graphic user interface (GUI) and the SNAP/RADTRAD plugin. Additionally, SNAP/RADTRAD is supported by the plotting tools software package, AptPlot.


2. How can I obtain the latest version of the SNAP/RADTRAD?
Individuals interested in obtaining this version of the RADTRAD-AC should check out the “Registration for the SNAP/RADTRAD Code” navigation link on the U.S NRC RAMP website.


3. Does the copy of the software on the U.S NRC RAMP website include both SNAP GUI and plotting tools software package, AptPlot?
No, the version of the code on the U.S NRC RAMP website is only the RADTRAD-AC and it does not include SNAP GUI or the plotting tools software package, AptPlot. The SNAP GUI with the SNAP/RADTRAD plugin and the AptPlot program is available from the APT website (https://www.snaphome.com).


4. How do I obtain a copy of the SNAP GUI and plotting tools software package, AptPlot?.
To obtain a copy of the SNAP GUI and plotting tools software package, AptPlot, users must go to APT website (https://www.snaphome.com/WebPages/Register.jsp)


5. Is there a fee associated with obtaining a copy of the RADTRAD-AC?
For US Federal, State and Local government agencies there is no fee to obtain the RADTRAD-AC. For all other users the fee varies based upon their designation category, see the table located at the “Registration for the SNAP/RADTRAD Code” link on the U.S NRC RAMP website.


6. Is there a fee associated with obtaining a copy of the SNAP GUI and the plotting tools software package, AptPlot?
There is no fee obtain the SNAP GUI and the plotting tools software package AptPlot. However, to obtain the SNAP GUI users must register on the APT website (https://www.snaphome.com/WebPages/Register.jsp) to receive an account (user name and password). AptPlot is a free “what you see is what you get” (WYSIWYG) 2D plotting tools software package.


7. Can I share my copy of the RADTRAD-AC with others?
No, RADTRAD users are required to complete a Non-Disclosure Agreement (NDA) for their copy of the software. The NDA states that the user agrees not to share their copy with any third party without obtaining prior written permission from the NRC.


8. What if I have multiple users at my facility, do I need to fill out an NDA for each user?
No, the NDA allows for the user to list multiple users of the software at their facility/site on the NDA.


1. What is RADTRAD and what is it used for?
RADTRAD is the acronym for the RADionuclide, Transport, Removal And Dose estimation computer software. RADTRAD was developed by the U.S. Nuclear Regulatory Commission (NRC) as a licensing analysis code used to show compliance with nuclear plant siting criteria for the site boundary radiation doses at the Exclusion Area Boundary (EAB) and the Low Population Zone (LPZ) and to assess the occupational radiation doses in the control room (CR) and /or Emergency Offsite Facility for various loss-of-coolant accidents (LOCA) and non-LOCA design basis accidents (DBAs). RADTRAD uses a combination of tables and numerical models of source term reduction phenomena to determine the time-dependent dose at the CR, EAB and LPZ for given DBA scenarios.


2. What is SNAP?
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 codes as well as extensive functionality for submitting, monitoring, and interacting with the codes.


3. What is AptPlot?
AptPlot is a free “what you see is what you get” (WYSIWYG) 2D plotting tool designed for creating production quality plots of numerical data and performing data analysis. AptPlot contains extensive scripting and GUI support for the manipulation and analysis of data sets.


4. Who typically uses the SNAP/RADTRAD?
SNAP/RADTRAD is one of the tools used by the NRC Offices of Nuclear Reactor Regulation (NRR) and New Reactors (NRO) to perform independent assessments of licensee applications and license amendments for existing plants (modifications to plant design or technical specification) pertaining to the siting criteria for offsite and control room doses following a maximum credible accident.


5. Is SNAP/RADTRAD only used domestically in the US?
No, SNAP/RADTRAD is used by many international government agencies and is an important computer code in the US NRC’s Radiation Protection Computer Code Analysis and Maintenance Program (RAMP).


6. Is there a forum that users can go to discuss questions related to the models used in the SNAP/RADTRAD?
Yes, the RADTRAD Forum is available to all visitors of the RAMP website (via “read-only” access). However, only RAMP members can post to the forum. To access the RADTRAD forum select the “SNAP/RADTRAD Support” navigation link on the U.S NRC RAMP website, which provides access to the “RADTRAD Forum”. RADTRAD Forum topics include:

  • Code Error (Bug) Reporting
  • Model Questions
  • General RADTRAD Usage Questions


7. Is there training information available for SNAP/RADTRAD and if so how can I get more information about the training available?
Yes, RAMP members can get training information (including presentations, SNAP/RADTRAD Workbook with exercises and short-length training videos) by selecting the “SNAP/RADTRAD Training & Presentation” link on the U.S NRC RAMP website.


8. Is there a user manual for SNAP/RADTRAD and where can I find technical documentation for the code?
Yes, there is a SNAP and SNAP/RADTRAD User’s Guide available at the “Download the SNAP/RADTRAD User’s Guide” navigation link. Additionally, RADTRAD technical documents including the NUREGs are available at the “Download the SNAP/RADTRAD Technical Documents” navigation link on the U.S NRC RAMP website.


1. What should I do if I get an error message or SNAP/RADTRAD crashes while I am using it?
Non-RAMP members should review the “Frequently Asked Questions (FAQs)” link and the“Error (Bug) Reports” forum board for the message. Non-RAMP members have “read-only” access to the “Error (Bug) Reports” forum board and cannot post new topics.

RAMP members have several tools available to help them trouble shoot and resolve SNAP/RADTRAD error messages and code crashes. Users experiencing error messages or code crashes should log into the U.S NRC RAMP website and select the “SNAP/RADTRAD Support" navigation link. This link will triage them through the following trouble shooting steps:



2. Is there a “Help” tool associated with the SNAP/RADTRAD?

Yes, the SNAP/RADTRAD contains a Help file which provides explanations of the SNAP GUI and RADTRAD plugin screens and default values for data entry fields. The technical information regarding the models and methods used by the RADTRAD-AC to perform calculations can be found in the SNAP/RADTRAD User Guide and at the “Download SNAP/RADTRAD Technical Documents” navigation link on the U.S NRC RAMP website.


3. Is there a contact phone number to receive help with the SNAP/RADTRAD software?
No, there is no single contact phone number for the SNAP/RADTRAD software. Since SNAP/RADTRAD development and distribution is a collaborative effort between the US NRC RAMP and RADTRAD Development Teams, users receive efficient and timely customer support by using the “SNAP/RADTRAD Support” navigation link on the U.S NRC RAMP website.