New developments in actinides burning with symbiotic LWR-HTR-GCFR fuel cycles: perspectives and challenges (original) (raw)

The long-term radiotoxicity of the final waste is currently one of the main drawback of nuclear power. Indeed, isotopes of Neptunium and Plutonium along with some long-lived fission products are dangerous for more than 100000 years. Actually, 96% of the spent Light Water Reactor (LWR) fuel consists of actinides, hence it is able to produce a lot of energy by fission if recycled. The effective exploitation of Uranium resources is intrinsically connected with an effective actinides burning. At the moment, it is clear that these goals can be achieved only by combining different concepts of nuclear cores in a "symbiotic" way, as suggested in the frame of the Generation IV Initiative. Light-Water Reactor -(Very) High Temperature Reactor ((V)HTR) -Gas Cooled Fast Reactor (GCFR) symbiotic cycles have good capabilities as far as the integral actinide exploitation is concerned. Particularly, HTR fuelled by Plutonium oxide is able to reach an ultra-high burn-up and to burn Neptunium and Plutonium effectively. In contrast, not negligible amounts of Americium and Curium build up in this core, although the total mass of Heavy Metals (HM) is strongly reduced. Americium and Curium are characterized by an high radiological hazard as well. Nevertheless, at least Plutonium from HTR (which is rich in nonfissile nuclides), Neptunium and, if appropriate, Americium can be used as a "driver" fuel for the GCFR along with large amounts of Depleted Uranium (DU): that is feasible with this kind of core thanks to its very good neutron economy. This paper focuses on the potentialities of the LWR-HTR-GCFR fuel cycle, highlighting also the challenges (both from the technological and neutronic points of view) to face with while realizing such a cycle. On the basis of the main technological constraints three possible (original) LWR-HTR-GCFR are proposed and their capabilities in actinides burning are assessed as well. Finally, some hints about designing an Am-Cm dedicated assembly are supplied.