Feasibility of MA Transmutation by (MA, Zr)H_x in Radial Blanket Region of Fast Reactor and Plan of Technology Development

This paper shows a feasibility study of transmuting minor-actinide (MA) by MA-zirconium hydride, (MA, Zr)H_x. And it also introduces a program of technology development for the MA target. A proposed concept of the (MA, Zr)H_x target can enhance the transmutation rate. The reason is that it densely contains both of MA and hydrogen. The feature creates the neutron energy spectrum shift to promote nuclear reactions. It was assumed in calculations that 54 assemblies of Am bearing target are arranged around an active core in a 280 MWe sodium-cooled reactor. The MA transmutation performance is significant: the irradiation of 615 days transmutes 39% of the initial Am amount, the Am transmutation rate is 67 kg/effective full power year; the transfer ratio of Am to repository reduces by one-fortieth. Integrity of the targets is predicted to be feasible on desk analysis: the maximum linear heat rate is about 310 W/cm. However, handling of the used targets is a matter of concern because the decay heat decreases to 7.5 kW/target after cooling period of 500 days. (author)