Research On The Phenomenological Model Of Fission

Nowadays,the society attaches great importance to sustainable development,which enables the rapid development of nuclear energy.The fission reaction of the nucleus,as one of the ways to release nuclear energy,has also received extensive attention.The accurate estimation of the total yield of fission products in nuclear fission is also of great significance to the calculation of nuclear reactor-related values.At the same time,the distribution of nuclear fission production is also of great significance for the study of the nuclear fission mechanism and nuclear structure.The GEF model("GEneral description of Fission observables"model code)is an empirical model that provides relatively accurate predictions for the fission observables of most nuclei.In this paper we mainly applies the GEF model to calculate the fission yield distribution of the Thorium isotope chain,and studies the neutron-induced fission with the different energy of incident neutrons,the electromagnetic-induced fission,and the systematic behavior of the nuclear fission of the same isotopes with increasing neutron number.We also use the CYFP code for the comparison,and find that the results form GEF model are closer to the experimental data.According to the calculation results,in the same thorium isotope,as the incident neutron energy increases,the probability of symmetric fission will increase,and the probability of asymmetric fission will decrease.Similarly,there will be multiple chance fission channels,and the relative contribution of(n,f)fission channels will decrease,and the contribution of other fission channels will increase.In the Th isotope chain,we found that as the number of neutrons increases,the contribution of asymmetric fission increases,the contribution of symmetric fission decreases,the valley becomes lower,and the peak becomes higher,indicating that the shell effect increases with the number of neutrons increases.In this work we also calculated the neutron-induced fission of ²³⁹Pu.We studied the variation of the yield and the fission mode with the incident neutron energy,and calculate the yield and mass distribution of different fission modes.According to the calculation results,when the incident neutron energy increases,in the plutonium isotopes,shell effect will be weaken,the symmetric fission contribution will increase,and the asymmetric fission contribution will decrease.At different positions of the mass distribution,the energy yield trends are different.The yield at the peak area decreases and the yield at the valley area increases.We also used the CYFP code to calculate the plutonium isotopes,and compared the calculation results with the GEF model,and found that the GEF model is closer to the experimental data.Comparing the calculation results of the GEF and the CYFP,it can be learned that the GEF model is consistent with most of the experimental data,and can provide a more reliable prediction for the lacking the yield experimental data.However,there are large discrepancies between the results from the CYFP code and the experimental data,and the parameters of the CYFP code should be adjusted properly to make the calculation more reliable.