Feasibility of FBR core concept with two different TRU-composition regions

Maruyama, Shuhei   

In the transition stage from LWR to FBR, it can be assumed for FBR to use high-MA-content fuel recovered from LWR SF. The high-MA-content fuel may cause decrement of design margin for safety parameters. As an effective MA-loading method, Am-Cm concentration in outer core fuel was proposed in this study, which leads to the improvement of safety parameters. It also causes the reduction of required coolant flow rate that results from the suppression of power distribution mismatch. On the other hand, high-MA-content fuel may bring difficulties in fuel design, for example, the reduction of melting point of fuel and the increment of helium production. The author employed an enhanced core concept which has two TRU-composition regions not only in the radial direction but also in the axial direction. This concept leads to the decreasing of the maximum linear heat rate and the maximum rare gases production of high-MA-content fuel. As a result of these improvements, main core characteristics were improved in comparison with the reference core. It is concluded that the new core concept proposed in this paper has the potential to mitigate the impacts on safety parameters and fuel design when high-MA-content fuel is loaded.