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About RELAP5-3D


International RELAP5
Users Group

RELAP5 Users Seminar 

Code Manuals

Version Releases


User Problems

RELAP5-3D is the latest in the RELAP5 code series developed at the Idaho National Laboratory (INL) for the analysis of transients and accidents in water-cooled nuclear power plants and related systems as well as the analysis of advanced reactor designs.

RELAP5-3D isometric image of the LOFT input model generated with RGUI.

The RELAP5-3D code is an outgrowth of the one-dimensional RELAP5/MOD3 code developed at the INL.  The most prominent attribute that distinguishes RELAP5-3D from its predecessors is the fully integrated, multi-dimensional thermal-hydraulic and kinetic modeling capability.

RELAP5-3D is available from the INL through membership in the International RELAP5 Users Group (IRUG).


RELAP5-3D News

2013 International RELAP5 Users Group Meeting, Training and Seminar
The 2013 RELAP5 Users Group Meeting was held from September 12-13 2013 in Idaho Falls, ID. There were over to attendees at the meeting and 25 technical presentations. The meeting was preceded by an Introductory RELAP5-3D training class that had over 30 in attendance.

Release of RELAP5-3D Version 4.1.3

The RELAP5-3D Team is proud to announce the release of the newest version of RELAP5-3D. This version identified as RELAP5-3D Version 4.1.3 will be available in October 2013.

For information on how to obtain the code, please contact Mr. Gary Smith at:

Mr. Gary Smith
Sr. Commercialization Manager
Idaho National Laboratory
PO Box 1625
Idaho Falls, ID 83415
Phone: (208) 526-3780

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Last modified: February 6, 2013