Efficient Method for Calculating Axial Diffusion Coefficients in Two-Dimensional Low Density Channel

抄録

An efficient calculation method of an axial diffusion coefficient which is applicable to multiregion and two-dimensional geometries has been developed. This diffusion coefficient which requires biquadratic numerical integration is quickly calculated by using a Good Lattice Point Method. Total computational time is about one-thirty hundredth that of Romberg's Method. The geometry dependency of axial diffusion coefficient is investigated. As a result the axial diffusion coefficient of a rectangular cross section of low density channel is larger than that of a square one, under the constraint that the channel volume is conserved.
Analysis of the reactivity worth measured for a square void channel in the Tank-type Critical Assembly (TCA) was performed using this diffusion coefficient. The calculated value agrees well with the experimental value, i.e. ratio of the calculated to experimental value (C/E) is 0.997.