The macroscopic fission cross section (ν∑f) for natural uranium to thermal neutrons is approximately 0.2274 cm-1 when modeled with UO2 and graphite moderation. This value is derived from the D&H tables, which provide essential data for reactor engineering. The discussion emphasizes the importance of neutron energy and atomic density, noting that the fission cross section varies based on the form of uranium used, such as elemental, alloy, or ceramic.
PREREQUISITESNuclear engineers, reactor physicists, and researchers involved in nuclear reactor design and analysis will benefit from this discussion.
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: