[en] The nonlinear lateral mechanical response of pressurized water reactor fuel assemblies is defined by a computer code, Fuel Assembly Mechanical Response Code (FAMREC), which was generated from a series of existing subcodes. A description, including some basic modeling assumptions, is presented for the class of problems which may be solved by the code. The various methods used for calculating fuel assembly impact forces and spacer grid crushing loads are outlined and a short discussion concerned with the overall convergence of the code is included. Results obtained from previous analyses using the code are considered and conclusions concerning the usefulness of these results are presented