Neutronics design of accelerator-driven system for power flattening and beam current reduction

Nishihara, Kenji  ; Iwanaga, Kohei*; Tsujimoto, Kazufumi ; Kurata, Yuji; Oigawa, Hiroyuki ; Iwasaki, Tomohiko*

In the present neutronics design of the Accelerator-driven system (ADS) cooled by lead-bismuth eutectic (LBE), we investigated several methods to reduce the power peak and beam current, and estimated the temperature drops of the cladding tube and beam window. The methods are adjustment of inert matrix ratio in fuel in each burn-up cycle, multi-region design in terms of pin radius or inert matrix content, and modification of the level of the beam window position and the height of the central fuel assemblies. As the result, we optimized the ADS combined with the adjustment of inert matrix ratio in each burn-up cycle, multi-region design in terms of inert matrix content and deepened window level. The maximum temperatures of the optimized ADS at the surface of the cladding tube and the beam window were reduced by 91 and 38 C, respectively.