[en] The Code System for Management of JPDR Decommissioning (COSMARD) was developed for use for effective planning and management of reactor decommissioning. Efforts were made to develop ; (1) data-processing algorithm using a tree structure which reflects decommissioning Work Breakdown Structure (WBS), (2) a set of commands to describe WBS and specific working conditions as input data, and (3) models to evaluate various project management data using simple mathematical formulas and unit factors. In preparing these models, dismantling work activities related to the Japan Power Demonstration Reactor (JPDR) were analyzed to find out fundamental work items and make suitable formulations for evaluating the manpower needs in both manual and remote dismantling work. Manpower needs for dismantling the JPDR components were then estimated as a sample calculation. An outline of COSMARD, its methodology and calculation models are discussed. (author)