A Continuous Transmutatkm System for Long - lived

An accelerator-driven transmutation system for long-lived nuclides of MA and FP was studied. The system with fluid targets may establish a continuous transmutation system having on-line separation facilities for the elements transmuted by spallation and fission reactions. To realize the effective incineration system MA is designed to be transmuted mainly through fission reactions by fast neutrons and FP of Tc-99 and 1-129 through neutron capture reactions by thermal neutrons. The total system of one accelerator with two fluid targets is discussed. In the preliminary study molten chloride salt of NaC1-(Pu,MA)Cla system is adopted for the target salt of MA transmutation, and Bi-Pb alloy for target fluid of neutron production to transmute the FP w“th a heavy water blanket. The amounts of MA and FP to be transmuted are estimated by the neutronics and thermal hydraulics calculations. The MA and long-lived FP produced approximately from 10 units of 3000 MWt LWR can be incinerated by about 25mA and 150mA of 1.5 GeV proton beam, respectively. The principle of the separation of the transmuted elements in the continuous transmutation system is continuously to remove the stable and short-lived transmuted nuclides(elements) without contamination from the long-lived nuclides(elements). The transmuted elements in the molten chloride salt target can be classified into 3 groups considering the chloride formation energy. First group is composed of inert gases and volatile chlorides, 2nd group noble metals and transition elements, and 3rd group alkaline earth metals, Ianthanide and yttrium chlorides. The He purge method and Cd extraction method for the on-line separation can be applicable to the 1st and 2nd group, respectively. The cold trapping method may be applicable to 3rd group. The oxidation method and He purge method may be applicable to separate Ru transmuted from Tc, and Xe from I in the FP transmutation system, respectively.