High-energy fission neutrons

There are three fast-flux reactors proposed for development the sodium cooled, the gas cooled, and the lead cooled. The fission cross sections for fast neutrons (high-energy spectrum neutrons) for all of the fissile actinides are nearly the same so the fast-flux reactors use all of the fissile actinides as fuel. The fast-flux isotopic fission cross sections are smaller than for thermal neutrons so the fraction of fissile isotopes (e.g., 235u 239pu, range of... 

The net yield of thermal neutrons from the fission of is higher than from that of and, furthermore, Th is a more effective neutron absorber than As a result, the breeding of is feasible even in thermal reactors. Unfortunately the use of the Th/ U cycle has been inhibited by reprocessing problems caused by the very high energy y-radiation of some of the daughter products. 

High-energy radiation may be classified into photon and particulate radiation. Gamma radiation is utilized for fundamental studies and for low-dose rate irradiations with deep penetration. Radioactive isotopes, particularly cobalt-60, produced by neutron irradiation of naturally occurring cobalt-59 in a nuclear reactor, and caesium-137, which is a fission product of uranium-235, are the main sources of gamma radiation. X-radiation, of lower energy, is produced by electron bombardment of suitable metal targets with electron beams, or in a... 

Man-made radioactive atoms are produced either as a by-product of fission of uranium atoms in a nuclear reactor or by bombarding stable atoms with particles, such as neutrons, directed at the stable atoms with high velocity. These artificially produced radioactive elements usually decay by emission of particles, such as positive or negative beta particles and one or more high energy photons (gamma rays). Unstable (radioactive) atoms of any element can be produced. 

Plutonium-239 also is produced from natural uranium by the so-called pile reactions in which irradiation of uranium-235 isotope with neutrons produces fission, generating more neutrons and high energy ( 200 MeV). These neutrons are captured by the uranium-238 to yield plutonium-239. 

Studies of the effect of neutron irradiation are divided into three groups slow or thermal neutrons, fission products and reactor neutrons. The slow neutrons are obtained from a radioactive source or high energy neutrons that are produced by deuterium bombardment of a beryllium target in a cyclotron and slowed down passing thru a thick paraffin wax block. The fission products in one case are produced when a desired sample is mixed or coated with uranium oxide and subsequently irradiated with slow neutrons. The capture of neutrons by U23S leads... 

The principles of balancing nuclear equations apply to all nuclear reactions. Nuclear fission occurs when a highly unstable isotope splits into smaller particles. Nuclear fission usually has to be induced in a particle accelerator. Here, an atom can absorb a stream of high-energy particles such as neutrons, Jn. This will cause the atom to split into smaller fragments. 

For example, when uranium-235 absorbs a high energy neutron, Jn, it breaks up, or undergoes fission as follows ... 

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