(NNDC82), and 3) branching fractions and decay schemes from the seventh edition of the Table of Lsotopes (Le78). Since each nuclide which we accounted for was the n&" member of an isobaric chain, the number of atoms at time t would increase or decrease relative to the number present at time of detonation because of decay and in-growth phenomena of precursor isobars. Decay and in-growth phenomena were accounted for using the following equation which was originally described by Bateman (BalQ0) and Later recast in a more general form by Skrable (Sk75). - ‘ne 2 Oo i. 7 (A, - 3) ae ECP aej esa) er E Abe |, n i=] jai ‘i,j+l j=i-p=n pei (4) p¥j where u rw A, = the number of atoms of the nth member of an isobaric chain at time t post-detonation per unit fission, the independent yield at t = 0 of the it® isobar in the An Lsobaric chain per unit fission, d; = decay constant of the j°" isobar, £5, j+1 « branching fraction of the jt) isobar leading to the creation of the jh + 1 isobar, t = time post-BRAVO detonation. The use of Eqs. (3) and (4) allowed us to calculate all fission products present at the time of exposure (see Table 13). We also included in Table 13, the important precursor transuranics and activation products which were based on the Tsuzuki measurements on day 26 (Ts55) and the use of parent- daughter transformation equations given by Bateman (Bal0). iv. Non-Fission-Fragment Nuclides Not Accounted for. The nuclides which may have been present at some level but which remain unaccounted for are 7 e, 24na, 55mn, 55 Ke, 39Pe, 37¢0, 586, 605, 64ey, 67cy, 240», 24lam, and 242cm. The decay of two short-lived activation products, 24a and 56uin, might have accounted for some of the exposure rate measured at 2.2 days at Rongelap Island. Borg tabulated the photon energy spectrum from a BRAVO fallout sample collected at Rongelap Island (B056). The fallout sample was reported to be analyzed at 4 days post-detonation. We determined that the spectrum has a minor peak energy around 850 keV. The intensity of the peak was about 5 to 72 of the total photon intensity. The nuclide 56Mn has a characteristic photon at 847 keV but so do 30 other nuclides which may have been present (RSIC73). Mather indicated that these short-lived activation products may account for as much as 20 to 50% of the photon intensity during the first day post-detonation; however, most 24Na and 56Mn activity would be observed close to the point of creation (Ma56). In the case of BRAVO this was near Namu Island, Bikini Atoll. Therefore, we doubt that 24Na and 29Mn contributed much photon exposure at Rongelap Island. We approximated the exposure rate contribution from all not~ accounted=-for nuclides at distances far from the detonation site on the basis of - 37 -