Cell geometry effects on nuclear characteristics in equilibrium state

Effects of the cell geometry on core performance are investigated for a liquid sodium cooled MOX fuel fast reactor at the equibrium state. The fuel pellet diameters and pin pitches are changed for a parametric study with Equilibrium Cell Iterative Calculation System (ECICS). The conventional fixed composition calculations are also performed to compare with the results of ECICS. The nuclear characteristics such as the neutron spectrum, onegroup nuclear constants, nuclide number densities and criticality are evaluated. The obtained results clarify the unique property of the equilibrium state in the cell geometrical change