RELAP5/MOD3 Code Manual

The RELAP5 code has been developed for best-estimate transient simulation of light water reactor coolant systems during a severe accident. The code models the coupled behavior of the reactor coolant system and the core during the severe accident transient, as well as large and small break loss-of-coolant accidents and operational transients, such as anticipated transients without scram, loss of offsite power, loss of feedwater, and loss of flow. A generic modeling approach is used that permits as much of a particular system to be modeled as necessary. Control system and secondary system components are included to permit modeling of plant controls, turbines, condensers, and secondary feedwater conditioning systems. RELAP5/MOD3 code documentation is divided into five volumes: Volume 1 describes modeling theory and associated numerical schemes, Volume 2 contains detailed instructions for code application and input data preparation, Volume 3 provides the results of developmental assessment cases that demonstrate and verify the models used in the code, and Volume 4 presents a detailed discussion of RELAP5 models and correlations. Volumes 1--4 are in varying stages of development. This document, Volume 5, contains guidelines that have evolved over the past several years through use of the RELAP5 code.