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The RELAP5-3D nuclear systems analysis code is available to US companies through the Gateway for Accelerated Innovation in Nuclear (GAIN) Initiative, allowing assessment of the code's suitability to explore concepts in advancing nuclear energy technologies.  With a substantial development pedigree and robust validation basis, RELAP5-3D is a key tool for the full range of transient and accident analyses in light water nuclear reactors, system design calculations, and regulatory licensing applications.  Extended capabilities are provided for thermal system analyses using a host of fluids in addition to water- including, for example, helium, nitrogen, carbon dioxide, lithium, sodium, potassium, lead-bismuth, and various molten salts.  The extensive user base of RELAP5-3D assures general familiarity in the nuclear energy community, comprising research institutes as well as regulatory agencies, thereby promoting a reduced learning curve for concept assessments in this GAIN offering.

Idaho National Laboratory manages the development, maintenance, and licensing of RELAP5-3D through the International RELAP5 Users Group (IRUG) and sets the license fee based upon IRUG membership participation level (see for details).  Participation in IRUG enables licensees the benefits of code support and commercial application.  Export and security control measures are established for RELAP5-3D, requiring software licensee review and approval for each individual user.  All approved recipients of RELAP5-3D hold responsibility for compliance with export and security control requirements.

A new licensing option created under GAIN allows US companies access to RELAP5-3D at the Single-Use Participant level at an annual cost of $3,000. The GAIN license provides single-seat use of RELAP5-3D, installed with system-specific executable and governing license files.  Source code and coupling options are not available with the GAIN license, and the licensee forgoes user support provided to IRUG Participants.

Under this GAIN license for RELAP5-3D, commercial use is disallowed.  Commercial activities include but are not limited to formal design calculations; engineering calculations supporting operations or maintenance procedures; development for application to plant simulators; assessment of system, structure, and component safety and/or reliability; and analyses utilized in licensing applications.  The GAIN license does allow use of RELAP5-3D for activities such as concept exploration, design parameter definition, and trade studies.

Requests for the RELAP5-3D GAIN license require description of the intended use, affirmation of non-commercial application, and confirmation of US business registration.  The requested information may be provided on the form provided here. Once approved for the GAIN license request, the RELAP5-3D License Administrator will communicate with the applicant Point of Contact for information required in completing the export and security reviews, and to provide payment information.  The annual GAIN license may be renewed up to 4 times, with a completed GAIN request at each renewal (export and security reviews are not required for each renewal). 


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