WORLDWIDE EFFECTS OF ATOMIC WEAPONS SAMPLING AND RESEARCH PROGRAM by 7 in. One of these involves first drawing & random subareas for sam- it, indeed, must remove particles however small. This latter point is susceptible to direct test, however, by use of several barrier series and 58 pling, and then within these subareas drawing m samples of soil, where km == N,the total sample number, each of which is equal to 1/Nth ofthe volume of soil required. The most advantageous sampling procedure will depend on the variability of the Sr°° level in the soil within the area and on the relative cost of going to the & subareas as compared with the cost of taking each sample of 1/Nth of the required volumeof soil. 3. The actual analysis of the data, once collected, is so straightforward (unless analyses other than the sample determination of the Sr°° level and inert strontium level are undertaken, e.g., analyses of the soil composition andits effect upon the availability to plant life) that there is no need to mention it. The primary problem is the collection problem andit is here, on matters of detail that cannot be foreseen now, that the help of a statistician is most needed. Similar consideration will enter into the design of the collection pro- gram for the other types of materials, e.g., animal bone, etc. ANALYSIS FOR STRONTIUM 90 Sampling The general principles of sample treatment and measurementare fairly obvious. One must, in the first instance, collect a fair sample of the realm being investigated. We must take a fair portion, bearing in mind the vast mixing problem, and then collect from this portion all the radioactive fission products present. From remarks made previously it is clear that the collection of all the radioactive fission products present may not be a simple task, particularly in the case of the atmosphere, for we have the 89 observance of the distribution of the radioactivity. That is, if the barriers are completely effective, the first in the series will absorb all the radioactivity. If it is true that diffusion barriers can be utilized to make a complete radiochemical assay on air, one might well develop a technique of producing otherfilters less security sensitive, but which will perform as well for the problem of removalof the colloidal aerosol fission-product matter from the atmosphere. This could be done by using bomb debris as test material, i.e., by purposely selecting fallout material as test mate- rial, or possibly by synthesizing similar material in the laboratory and conducting tests on various filters. This work could be done in the Carbide and Carbon Corporation laboratories in the diffusion plant at Oak Ridge. Professor John Turkevich of Princeton University has observed that the particles produced by an electric arc between aluminum electrodes in air have particle sizes in the range of 0.01 » and smaller. It is conceivable, therefore, that the use of radioactive material for the electrodes would allow one to synthesize an aerosol similar to that produced by the atomic bombs. Then this might be used in developing adequatefilters. In sampling the hydrosphere one must remember the propensity of the radioactive material to pass throughfilters. It seems, therefore, that evap- oration is necessary. The evaporation of considerable volumes of wateris an unsavory task, but in the absence of information as to how to be certain of the removal of the fine colloid, no alternative seems to be available. Following evaporation, the salts left can be treated for the dissolution of such inert materials as silicon dioxide, aluminum oxide, etc., so that the radioactivity will be in true solution. The procedure for this is well known to be the treatment with about 50 per cent hydrofluoric acid solution in platinum vessels. This procedure will suffice. It may be unnecessarily possibility that a considerable portion of the radioactive particles invalved are of a very small size—i.e., less than 0.1 » in diameter and possibly of drastic, however, as only direct test can show. The carrier elements, such isolate. The method of electrostatic precipitation 1s presently being exploited by the Stanford Research Institute and by the New York Operations Office of the AEC. The results are encouraging. Additionally, we recommend that a study be made of possibilities of the diffusion barrier, since it is clear from its physical characteristics that misleadingly tow assays could be obtained. It is difficult to overemphasize the importance of guarding against the lost part of the radioactivity in ultra-fine colloidal form. Lithosphere sampling is quite difficult in that the treatment of any the order of 0.01 yw. Particles of this dimension are extremely difficult to as strontium, should then be added and an ordinary radiochemical analysis