“…Under the operating conditions of the generator, the 232 U will eventually bleed off the column; however, 228 Th and the daughters with higher Z 212 Pb remain strongly sorbed, Table 14. Due to the 69.8 year half-life of 232 U and the long 1.912 year half-life of 228 Th the bleeding of the 232 U, even if all in one 2 mL 212 Pb elution, will be unable to grow enough 212 Pb into solution to be detected over the approximately 3 hour experimental time frames. However, if 228 Th were to breakthrough, the generator would slowly degrade and detectable amounts of 212 Pb would grow into the experimental solutions during the 3 hour time frames.…”