CHAPTER [Ul RADIOCHEMICAL DETERMINATION OF FISSION YIELD A. THEORY The fission yield of a device can be measured by radiochemical techniques by using macroscopic tracer of sufficient amount to allow a measure of the fraction of total debris collected in a sample. From this bomb fraction and the absolute number of fissions collected in a sample, the total fission yield can be measured, The bomb fraction tracer is placed in such a manner as to insure that the material will mix completely with the fission products and be distributed uniformly with the fission products throughout the post-shot cloud. Aircraft equipped with units designed to collect representative samples of debris on filter papers are flown through the cloud. The samples are removed from the aircraft by remote handling techniques, the radiation levels measured and the samples packaged and returned to the laboratory for dissolution and analysis. Fractions of the solution con- taining the filter paper are thei taken for measurement of the bomb fraction and the absolute number of fissions. the tracer. determined. Uranium in the form of U30g is used as Molybdenum 99 has been chosen as the fission product to be The total fissions are given by Total fission = Initial uranium Uranium in sample x Fissions in sample. Since one megaton TNT equivalent is defined as 10! calories and the prompt energy per fission is 179 Mev, 1.45 x 1076 fissions are equivalent to one megaton, 10 B. 2 ovo dShT mt ete eb 1. Bomb Fraction Tracer TECHNIQUES | | uw 41 VS we The bomb fraction tracer to be used idy -) 7) Jj pleted in u“3> in the form of uranium oxide (U,0, . ; | guranium partially de- The uranium oxide has a bulk density of about 2.5 z/cc and will be packaged in approximately 100-pound containers. 10R.B. Leachman, Phys. Rev. 87, 444 (1952); R. B. Leachman and W. D. Schafer, Can. J. Phys. 33, 357 (1955); and S. R. Gunn, H. G. Hicks, H. B. Levy and P. C, Stevenson, Phys. Rev. 107, i642 (1957). y, 9688583 \ 45 - \