抄録
The mobile-chord method is applied to the method of characteristics (MOC) to reduce spatial discretization error of ray traces. In the mobile-chord method, the offset of a ray trace in a strip depends on the azimuthal angle to cancel the spatial discretization error. Though the mobile chord method has been used in the evaluation of the collision probability, its application to MOC has not been tried yet. The mobile chord method is implemented in the AEGIS code, which is a lattice physics code based on MOC. Verification calculations are carried out in the pin-cell geometry of the C5G7 benchmark problem using UO2 and MOX fuels. Calculation results indicate that spatial discretization error of the mobile chord method is smaller than that of the equidistant ray trace method, which is commonly used in conventional MOC codes. Since the mobile chord method can be used with the cyclic ray trace method, it will be an attractive candidate for MOC codes.
