ye AVAILABILITY OF SAMPLES A large number of contacts were made with people and institutions that have been or are still involved with the analysis or utilization of nuclear debris to ascertain the existence and location of samples. AS we expected, the results were disappointing. A rather considerable inventory still exists of samples collected by aircraft at the weapons laboratories. A few selected samples are still available at LFE Environmental. Fallout collections are few and far between. The principal reasons are that many of these fallout collections were used up in their entirety for analysis and that a number of samples was discarded some years ago. Some fallout samples are now under the control of the Nevada Operations Office. These samples are mostly from Areas 11 and 13 ("Program 57") and have been collected at distances greater than 1 mile from GZ. Some Roller Coaster samples on planchets are availabie at LFE Environmental. About 200 fallout samples from Shasta, Johnie Boy, Small Boy, and Sedan are located at Camp Parks near Livermore, California. All these samples are well documented with regard to shot location and collection method. This documentation is still in the possession of the original investigators. In addition, a few as yet nondescript samples may be available at Battelle-Northwest in Richland, Washington, and at the Ballistics Research Laboratory in Aberdeen, Maryland.* A complete inventory of all available and relevant samples has not been made. DISCUSSION A large body of data has been generated on fallout as well as on clouds from many events of different type that have contaminated the test sites. Projects were conducted independently, each having its own objectives and its own experiments. As a Tesult, there was little correlation between experiments, and very few review articles or reports in which results were put together and critically examined. Even data from different projects relating to single shots often remained uncorrelated, The correlation of data of similar type from different tests is difficult because sample collection methods, analytical techniques, and data presentations differed. Sometimes sample documentation was inadequate. Cross-calibrations were almost nonexistent. Subjectivity in reporting was sometimes present, for example, in the case of shape and color. The reasons for data acquisition and the use to which data have been put are quite varied. Emphasis has changed over the years, in part because people were getting smarter, in part because requirements changed, Data acquisition for the purpose of evaluation of device performance has always occurred. Such data are of limited use for today's needs for fallout characterization. In the early days, understanding particle and fallout formation and the formation of radiological countermeasures were the prime objectives for most of the projects, the former objective having persisted for a long time. This particular objective was also sought in a number of projects involving laboratory simulation of conditions under which fission products would be incorporated in particles. The definition of the fallout field and its properties was also of interest for certain military applications, and became of interest to the Plowshare program (Peaceful Use of Nuclear Explosives) for what today would be called Environmental Impact Assessment. Data were also generated, particularly during the last ten years or so, to provide inputs to fallout models for model verification and for predictive purposes. Estimates of soil burdens in nuclear clouds also result from these and similar activities. Some data not separately discussed in this review were generated for the purpose of evaluating effects from accidents; for example, data from the Roller Coaster and Kiwi (nuclear propulsion reactor} tests. Studies of the modes of entry of fallout or radtonuclides into the biosphere have always provided an important impetus to the gathering of a variety of data. Solubility studies were certainly directed towards this purpose. In recent years, fallout-particle characterization studies also have increased for use in such studies. Thus, hazard assessment, either of already contaminated areas or in a predictive mode, has become the prime interest. O£ particular interest at the present time is the characterization of the radioactive fallout particles at the Nevada Test Site, especially with regard to theie chemical and radiochemical properties. The plutonium and americium content of the particles, the concentration as a function of the particle size, the distribution within the particles, the chemical form, the “soiubility," are all of interest for the estimation of the redistribution of fallout (by wind or mechanical action) and modes of entry into the biosphere. Many of the data, once they are correlated, are directly applicable to the question of fallout characterization. However, plutonium, being an alpha emitter, waa more or less fgnored during the earlier work. Nevertheless, useful inferences may be made from what has been observed generally with regard to radionuclide fractionation and some actual data that are available. Making inferences with regard to transuranics concentrations and distributions, although useful, is not wholly satisfactory. Requirements that have been laid down or that may be formulated in the near future necessitate a more definitive characterization of the transuranica-bearing particulates and their temporal and chemical behavior in the environments in which they exist. Such a characterization is by no means a trivial task. Ideally, a physical separation of these particulates from the soil particles is required. This is a task which *The BRL samples have now been transferred to LFE Environmental. 243 242