The discussion revolves around the macroscopic fission cross section for natural uranium in relation to thermal neutrons. Participants explore the dependencies of this value on various factors, including neutron energy and the physical form of uranium.
Participants express varying views on the dependencies of ν∑f, particularly regarding neutron energy and the form of uranium. There is no consensus on a definitive value for the macroscopic cross section for natural uranium, as the discussion remains open to interpretation based on different conditions.
The discussion highlights the importance of specifying neutron energy and the physical form of uranium when discussing cross sections, indicating that these factors significantly influence the values being sought.
Developing a value for ∑f depends on the atomic density, which depends on the form, e.g., elemental, alloy or ceramic. What form is one considering? The value of ν depends on neutron energy, and in a thermal spectrum, it will depend on U-235.Kirk Truax said:
Yeah, but that's for fast neutrons. Fast neutrons from fission have a peak distribution around 1 MeV and the energy distribution falls off rapidly up to 10 MeV. With d+t fusion, one gets up to 14.1 MeV neutrons. To go higher, one pretty much needs 20+ MeV protons and spallation reactions.jim hardy said:
Astronuc said:
Hey guys,Astronuc said: