This report describes the structure of the computerized Fuel Performance Data Base (FPDB), which contains all nuclear fuel irradiation data produced under EPRI sponsorship or obtained under information exchange agreement. It also explains the operation of the interactive FORTRAN program, RIMS, that accesses and manipulates the data base. The software is designed to run on mid- to large-size computers. It displays data in tabular or graphic format on paper, CRT, or magnetic tape.