U-233 BREEDING MEASUREMENTS IN A THORIUM-OXIDE BLANKET ASSEMBLY USINGA (D,T) ACCELERATOR NEUTRON SOURCE

Uranium-233 breeding studies are carried out in a compact thorium-oxid e cylindrical blanket assembly surrounded by a thick polypropylene ref lector in a fusion neutron environment. The assembly consists of II ri ngs of thorium-oxide rods stacked in a hexagonal geometry with a centr al through channel for the 14-MeV(d, t) neutron source. A total of 120 thorium-oxide probes are inserted inside the rods in different axial and radial locations in the assembly, which is then subjected to 14-Me V neutron irradiation for 25 h. Protactinium-233 gamma activity produc ed in the probes because of neutron captures in the thorium is measure d using a high-efficiency, high-purity germanium detector: The measure d U-233 production rates are fitted to obtain axial and radial distrib utions for different rings. These distributions are used to obtain the total U-233 breeding in the whole assembly. The integral measured val ues are found to be in good agreement with the calculated values obtai ned employing the MCNP Monte Carlo code using the BMCCS2 cross-section library.