This document is a compilation of information pertinent to the decommissioning of surplus nuclear facilities. This handbook is intended to describe all stages of the decommissioning process including selection of the end product, estimation of the radioactive inventory, estimation of occupational exposures, description of the state-of-the-art in re decontamination, remote csposition of wastes, and estimation of program costs. Presentation of state-of-the-art technology and data related to decommissioning will aid in consistent and efficient program planning and performance. Particular attention is focused on available technology applicable to those decommissioning activities that have not been accomplished before, such as remote segmenting and handling of highly activated 1100 MW(e) light water reactor vessel internals and thick-walled reactor vessels. A summary of available information associated with the planning and estimating of a decommissioning program is also presented. Summarized in particular are the methodologies associated with the calculation and measurement of activated material inventory, distribution, and surface dose level, system contamination inventory and distribution, and work area dose levels. Cost estimating techniques are also presented and the manner in which to account for variations in labor costs as impacting labor-intensive work activities is explained.