In reply to Eric Walker's message of Tue, 8 Dec 2015 16:18:31 -0600: Hi, Note that with alpha fusion some extra energy is available, so I suppose that in theory that means you could start a little lower, however that would also not be spontaneous fission, but rather triggered fission.
If you add a neutron to U238 it doesn't fission, despite the addition of 4.8 MeV. So unless the alpha fusion releases quite a bit more than this, I don't think you are going to get much fission for lower isotopes. (Neutron addition to U235 yields 6.5 MeV, which apparently is enough, at least for this somewhat unstable isotope.) Note that addition of 2 D's or 4 H's yields some 20+MeV more than addition of an alpha, making such a combination much more likely to be able to trigger fission. >I had in mind atomic mass (i.e., nuclides in the neighborhood of >zirconium). I got this tidbit from Wikipedia (second paragraph): > >https://en.wikipedia.org/wiki/Spontaneous_fission > >I have now added a reference to this page in the paper. Wikipedia shows >"(SF)" in some cases for isotopes in this range, e.g., in the table on the >righthand side for niobium: > >https://en.wikipedia.org/wiki/Niobium > >I think this means, "theoretically there could be spontaneous fission, but >it hasn't been observed." I've also been assuming that this is also the >approximate threshold for the start of fragmentation reactions. > >Eric [snip] Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/project.html
