Photo-transmutation of long-lived nuclear waste 135Cs by intense Compton γγ-ray source

• The photo-transmutation rate of 135Cs is 1.6 × (106–108) by using SLEGS.
• The photo-transmutation products of 135Cs are all short-lived or stable.
• The number of transmutation reactions would exceed 1014 per hour by ELI-NP.
• Photo-transmutation by intense Compton γ-ray source is an efficient approach.

MeV-range Compton γγ-ray beam via Compton scattering of a laser pulse against a high-current relativistic electron beam can be used to induce photo-transmutation reactions. In this work, we investigate through Monte Carlo simulations the possibility of transmutation of radioactive nuclear waste, by high-intensity Compton γγ-ray source, for the long-lived 135Cs with a half-life of 2.3 ×× 106106 years into short-lived 134Cs with a half-life of 2.07 years, or into stable nuclide 133Cs. Our simulation results show that the transmutation reaction yield is in the order of 6 ×× 109109 per hour for a given γγ-flux of 2 ×× 108108 phs/s that can be obtained from the Shanghai Laser Electron Gamma-ray Source which is under construction. The transmutation capability of worldwide Compton γγ-ray facilities is also evaluated, showing that the photo-transmutation induced by brilliant Compton γγ-ray source, such as ELI-NP could be an efficient approach to transmute long-lived radioactive nuclear waste.