where V, = total volumeof filter paper solution, A, = aliquot of filter paper solution; V> = total volume of ethyl acetate for sample; Ay = aliquot of ethyl acetate for sample; Ug = weight of uranium in standard solution; Vg = volume of standard solution; Ay, = aliquot taken of working standard; 1000 = dilution of standard to working standard; A, = aliquot of ethyl acetate for standard; V3 = total volume of ethyl acetate for standard; Fy = fluorometer reading of sample; F, = fluorometer reading of blank; Fs = fluorometer reading of standard; Ur = total uranium on barge. f. Reagents. Mix 450g Na,CO3, 450 g K,CO;3, and 100 g NaF reagent Before mixing any batch grade for approximately six hours ina ball mill. of them fuse them in this ratio to be sure they are low in uranium content and do not provide a blank of interfering intensity. This mixture is somewhat hygroscopic and must be stored in a tightly closed container or preferably a desiccator. Prepare a saturated aqueous solution of Al(NO 3 )3. fluorescent test to be suitably free of uranium. 9 H,0 known by If necessary extract ura- nium from this solution by the use of ethyl acetate. 6. Measurement of Number o1 Fissions in Sample a. Discussion of Method. The amount of fission-produced energy in a nuclear explosion is directly related to the amount of fission-product activity formed. It is not practical to attempt to do a complete radiochemical analysis of all fission products in the debris, since most species decay with inconvenient rapidity; it is, however, possible to analyse for selected fission products of knownfission yield. The most convenient and direct measure of fission is obtained from the analysis of the active debris for the species Mo 99° This nuclide is produced in the thermal-neutron induced fission of y23° and Pu 239 with a fission yield (i.e. atoms Mo?? formed per fission event) of 0.06, or 6%. (See for example, J. O. Blomeke, Oak Ridge National Laboratory Report No. ORNL-1783, Nov. 2, “re 1955). The decay scheme of Mo?? is shown in Figure 14. If the radiations of Mo?” are detected with a gas-flow proportional counter or a Geiger-Muller Counter, only the 8 particles from the decay of Mo?? are counted with good efficiency. Corrections for the presence of genetically re- lated Te?? beta radiations as well as all gamma radiations may be neglected Conversion electrons from Tc 99m are absorbed more than 99 percent byt air gap and counter window. - 49 - XY