Hello, all :D
I regret to inform you that uranium 234 is a nuclear explosive: https://www.bnl.gov/isd/documents/43872.pdf This is not the form I first saw these neutron cross sections, they were earlier ones and had absorption and fission lines printed on the same graph. Fission exceeds absorption in the range of 1 - 5 million electron volts (MeV). Nubar, the number of neutrons emitted per fission, ranges ...