2 FREILING, CROCKER, AND ADAMS Finally, the directions that we expect future efforts to take are indicated. These include a sensitivity analysis of our prediction sys- tem, extended fractionation correlations, model refinements, gnodel extensions_to new conditions, the retrieval of information from og debris, and laboratory studies of fallout formation ungerirreversible conditions. INTRODUCTION We have been asked to describe in this paper the project on studies of nuclear-debris Orman that we are carrying out at NRDL for the Fallout Studies Branch, U. S. Atomic Energy Commission (AEC). This project is entitled “The Formation, Distribution and Characteristics of Nuclear Debris.” However, if we were to limit this paper strictly to this part of our nuclear-debris program, we would present a very incomplete picture of our efforts. We have therefore chosen to preface this paper with a few remarks on what we are trying to do and for whom we are doing it. Figure 1 is a schematic presentation of the Physical Chemistrm, Br Seats mate ie ape the present and in the récentegaete~Gtierreiaet& oa coded to identify Sponare VOXeES various The ry. only where necessa sorship. Next to the AEC, the Defense Atomic Support Agency (DASA) sponsors most of our work. The focal point, the ultimate goal, is prediction capability. This is indicated by the box labeled “Model of For- mation and Properties of Nuclear Debris.” As input this box requires basic data from nuclear and physical chemistry, in addition to empirical relations such as scaling functions and fractionation correlations. the The scaling functions come from laboratory experiments and fractionation correlations from the analysis of nuclear debris. In addi- tion to NRDL, data come from various sources. This paper reports primarily, but not exclusively, on research our completed or nearly completed in the four following subprojects of work for the AEC: a4 ND 1. Prediction of fractionation effects Prediction of radiological properties 3. Fractionation correlations 4. Laboratory studies on we Also included in each section is an indication of the future directi visualize these studies will take.