Transmutation Of Long-life Fission Production By Using High Intensty MeV Gamma-ray

Safe disposal of long-lived fission products?LLFPs?is a key problem to be solved urgently in the process of sustainable development of nuclear energy.Using nuclear reaction to transform LLFPs into short-lived or stable nuclides is expected to solve the potential hazards of LLFPs,thus eliminating the bottleneck problem of nuclear power development.As a powerful supplement to neutron transmutation,gamma nuclear transmutation refers to the irradiation of LLFPs with high-flux gamma beams in the nuclear giant resonance energy region?GDR?to induce photonuclear reactions and transmute them into short-lived?or stable?and low-toxic?or nontoxic?nuclides,thus realizing the safe treatment of nuclear waste.In recent years,the construction of large scientific facilities such as ultra-strong ultra-short laser and particle accelerator has provided unprecedented opportunities for the generation of high-throughput MeV laser Compton gamma source.Under this background,this thesis mainly uses MeV-level high-flux gamma light source to carry out the research on the transmutation of LLFPs,and proposes a new scheme of LLFPs transmutation based on proton resonant gamma beam.The research results provide theoretical basis and technical support for future LLFPs transmutation experiments based on high flux,quasi-single energy gamma light sources.Laser Compton Light Source?LCS?is an x/gamma light source with high flux,quasi-monochromatic and adjustable energy,which uses high energy electron beam and laser pulse to realize inverse compton scattering.Based on the international open source Geant4 software package,the LCS-driven LLFPs transmutation physical model is built,and the typical LLFPs nuclides ¹³⁵Cs,¹²⁶Sn,¹⁰⁷Pd,⁹³Zr in spent fuel are studied.The reaction type and product distribution of photonuclear transmutation are simulated and diagnosed,and the dependence of photonuclear transmutation rate on LLFPs target geometry is obtained.The results show that when the incident light energy is 0-22 MeV and the flux is 10⁸ phs/s,the photonuclear transmutation rate can reach 10⁶/s under the optimal transmutation target geometry.Strong fluid proton resonance gamma source is an effective way to generate single energy gamma rays in MeV energy region.A proton resonance capture reaction model based on the interaction between the strong fluid sub-beam and the ⁷Li target is constructed.Two single-energy gamma rays with energies of 14.8 and 17.6 MeV are generated,and the emission direction of the gamma rays is isotropic.The dependence of proton resonance gamma light source output on incident proton beam energy and ⁷Li target geometry parameters is studied.It is found that proton beam with a current intensity of 10mA and energy of 441 keV can produce a gamma light source with a flux of2.1×10⁹/s.Furthermore,the resonant gamma light source is used to simulate the photonuclear transmutation of radioactive iodine and cesium,and the photonuclear transmutation rate is 5×10⁷/s under the optimal target thickness.In addition,the influence of two transmutation layouts of planar target and hollow cylindrical target on transmutation effect is discussed,and it is found that the transmutation effect of the latter is twice that of the former.