"Im the calibration of the ‘counting equipment to yield disintegrae tion rates, calculations were performed involving the flux of a thermal neutron irradiation of U°32 and the fission mygetce of pere inent, nuclides from the resultant fission of the U If the neutron flux and fission ylelds are each assigned a precision of 10 per cent, the microcurfe values have an additional error of about . ” ly per cent independent of the analytical procedure, All but two of the ar? 95 analyses performed on the size~separated samples at early times after shot had to be repeated because of wide variations in results, Better reproducibility was obtained when the analyses were made & mnths later, There appeared to be poor exchange between carrier and tracer in the early analyses because alnost identi- _ cal chemical yields among the aliquots produced significantly different activities, Similar anomalous behavior of tracer zirconium has been observed in these, oratories during other investigations, The poor. spreads in the Galt analyses can also be attributed to poor exchange pryperties between the carrier and tracer, This characteristic o Ca4> has also been reported by Jacobs and Jordan. 19 5.2 Ae oe meme The BalhO contamination of the sodium analyses ha8- never been resolved, Repeated attempts to simlate the test shot samples have hever reproduced this bariwm contamination in the sodium fraction of the cation elution, No satisfactory explanaticn: can be offered for this anomalous behavior of barium which has been observed only ia these sot samples, EVALUATION OF SIZE SEPARATION:ASD, AUTORADIOGRAPH TECHNIQUES "There are certain inherent difficulties in any method of particle size separation, Standard sieves are quite satisfactory for discrete, spherical particles, although the size fractions obtained show a considerable distribution of sizes on account of variations in the spacing of the screens, If the particles are irregular in shape, they may pass through the ‘screens in varicus orientations so as to produce . very broad distributions. Frangible or agglomerated particles may be broken up by the agitation necessary to carry out the separation. These factors are greatly influenced by the length of time the sieves are shaken, This time was kept to a minimm in order to minimize these _ effects. Nevertheless the size distributions were quite broad and did not compare well with the sieve sizes, as may be seen in Table5.2. 37 hail SECRET — RESTRICTED DATA