Because the fission representation goes to infinity at zero time, the ratio of fission activity to uranium capture activity mst be found at some other time. In general, the time chosen wag that at which the uranium capture activity was measured. A variation in this value could be used as a method of indication of fractionation of uranium capture products with respect to fission products. 3.3 el Shot 1 Since little experimental decay data were obtained prior to 250 hours, a composite neutron capt decay curve was coystructed for times shortly after the shote ves, 289, Np*29, peeand Np*40 were found to be significant contributors to the decay curve. the parent—daughter relationship (ete M2") ug From (3.6) Apy= activity of 0239 at initdal tine where Ag = activity of daughter Np239 wh = decay constant of y239 ug = decay constant of Np239 t+ = tim after shot In the case of the U239 and Np23? decay scheme, u, is much greater than tu, ande@1* 1s mch less than eW%2" at any time after initial timee hence Ag + Ag® (367) thus, setting t = 0 (3-8) of Np239 can be found from Eqe 308, ass a rotatingectivityef 1 te 1239, Similarly, in the case of Np240, it can ° he shown that its activity equals up/(ug — wu.) times the activity e ibrium is reac therelativeactivities of ye? to U239 and U240 to 0239 are determined by the ratio of their decay constants multiplied by bhgir ida s The relative activity and decay constants of U®~'; cankure U<77, aes U 40 and Np240 are gummarized in Table 3.l. 38