Numerical Studies of Axial Fuel Shuffling

Abstract

The concept of traveling wave reactor (TWR) applies the mechanism of self sustainable and propagation nuclear fission traveling waves in fertile media of 238U and 232Th to achieve very high fuel utilization. However, the long wave length of such fission traveling wave puts a limit on the applicability of the TWR concept. The axial fuel shuffling strategy is proposed based on the mechanism of asymptotic nuclear fission traveling wave, and is applied to a sodium-cooled fast reactor (SFR) loading metallic 238U fuel. The multi-group deterministic neutronic code ERANOS with JEFF3.1 data library is used as a basic tool to perform the neutronics and burn-up calculations. The calculations are firstly performed in a 1-D case for parametric understanding, and further extended to a 2-D R-Z case. The shuffling calculations for the 1-D and 2-D SFR model described in this paper brought about some interesting results. The results indicate that k_eff parabolically varies with the shuffling period, while the burn-up increases linearly. The highest burn-up achieved in 2-D case is 46at%. The power shape distortion in 2-D case is observed, and the power peaking factor is much higher than that in 1-D case, but it decreases with the shuffling period increasing.