Proposal of an Effective Initial Guess Scheme for Higher Harmonic Mode Calculation of Boiling Water Reactor Cores

抄録

The technique of producing the initial flux guess in resolving the higher harmonic modal flux of a heterogeneous reactor core was presented based on the Ringhals-1 core data. From these studies, the initial guess scheme making use of a two-dimensional horizontal plane, Scheme C, showed excellent convergence performance. In Fig. 1(b), the magnitude of the relative error in Scheme C at the first 150 iterations was reduced to 1.0e^-2, compared to 1.0e⁺⁰ in the reference case. From the cost performance point of view, Scheme C is most efficient because it needs only two-dimensional fine mesh calculation. In addition, the results of our method was compared with the LPRM signals of Ringhals-1 test point in which the regional oscillation was observed and showed good agreement.