This document provides a description of a model of the r_dionuclide behavior in the reactor coolant system (RCS) of a light water reacbor during a severe accident. This document serves _s the user's manual for the computer code called VICTORIA, based upon the model. The VICTORIA code predicts fission product release from the fuel, chemical reactions 5et.ween fission products and structural materials, vapor _nd aerosol behavior, and fission product decay heating. This document provides a detailed description of each part of the implementation of t5_ model into VICTORIA, the numerical algorithms used, and the correlations and thermochemical data necessary for determining a solution. A description of the code structure, input and output, and a sample problem are provided. The VICTORIA code was developed upon a CRAY-EMP at Sandia National Laboratories in tb_ U.S.A. and a CRAY-2 and various SUN workstations at the Winfrith Technology Centre in England.