Breeding ratio analysis of a fast reactor cooled by supercritical light water

The purpose of the study is to analyze the breeding ratio of a supercritical pressure light water cooled fast reactor (SCFR) and to design a breeding core of SCFR. The sensitivities of core parameters to the breeding ratio are analyzed. The core is designed by coupling two-dimensional R-Z neutronics and a multi-channel thermal-hydraulic calculation. The parameters which have high sensitivities to the breeding ratio are the diameter of the fuel rods and the diameter of the coolant tubes of the briquet blanket. The briquet fuel assembly means that the coolant flows in tubes and the fuel is contained outside of the tubes, "a tube in shell" fuel assembly. For increasing heavy metal fraction, briquet blanket is considered. The positions of the fuel and the coolant are exchanged for increasing heavy metal fraction in briquet blanket. The breeding ratio of SCFR is 1.021 with fuel rod type blanket and 1.034 with the briquet blanket. When both seed and blanket are composed of briquet type fuel elements, the breeding ratio reaches 1.046 because of the high fuel volume fraction. The reactor power also increases with the briquet core. But SCFR can be a breeding reactor even if both seed and blanket consist of rod type fuels.