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SNAP/RADTRAD General Usage FAQs


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.