Radioactivity computation of steady-state and pulsed fusion reactors operation

Abstract

The International Thermonuclear Report (ITER) is expected to operate in a pulsed operational mode. Accurate radioactivity calculations, that take into account this mode of operation, are required in order to determine precisely the different safety aspects of ITER. The authors previous examined analytically the effect of pulsed operation in ITER and showed how it depends on the burn time, the dwell time, and the half-lives. That analysis showed also that for ITER`s low duty factor, using the continuous operation assumption would considerably overestimate the radioactivities, for a wide range of half-lives. At the same time, the large improvements in the quality and the quantity of the decay and the cross-section data libraries has considerably increased the computation times of the radioactivity calculations. For both reasons it is imperative to seek different methods of solution that reduce the computational time and can be easily adopted to the treatment of the pulsed operation. In this work, they have developed algorithms based on several mathematical methods that were chosen based on their generality, reliability, stability, accuracy, and efficiency. These methods are the matrix Schuer decomposition, the eigenvector decomposition, and the Pade approximation for the matrix exponential functions.