Zachry Nuclear Engineering
RETRAN is a NRC accepted transient thermal-hydraulic analysis code designed to perform licensing and best-estimate evaluations of light water reactors.

The RETRAN series of codes have evolved since the development of RETRAN-01 began in 1975, to the recently released versions of RETRAN-3D. In a partnership with sponsoring organizations, Electric Power Research Institute funded the RETRAN project while modeling features and code development were directed by the code users. EPRI sponsors have required carefully planned code development activities that have resulted in complete documentation, extensive validation and verification efforts, and carefully controlled maintenance procedures. Released versions of the RETRAN code are maintained under a formal quality assurance program to ensure that modifications are properly made and that they do not yield unexpected changes to RETRAN analysis results.