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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.

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).

The code is currently configured to run on both Linux and Windows. Operating systems and compilers supported are:

  • O/S
    • Linux: OpenSUSE: 13.2 (x86_64)
    • Windows: Windows 7, SP1

  • Intel compiler designation
    • On Linux: Version 13.1.3
    • On Windows: Composer XE 2013, SP1, Update 2

RELAP5–3D News

The RELAP-5 International Users Group Seminar and Training Workshop was held October 2–7, 2016 in Idaho Falls, Idaho. Please follow the "RELAP5 Users Seminar" link to view the presentations made at the meeting and also training workshop agenda.

License/IRUG Membership Fee Increase

Release of RELAP5–3D Version 4.3.4

The Idaho National Laboratory is pleased to announced that on October 9, 2015 the latest version of RELAP5-3D, RELAP5-3D Version 4.3.4 was released.

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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