SOLITARY BURN-UP WAVE SOLUTION IN A MULTI-GROUP DIFFUSION-BURNUP COUPLED SYSTEM

A two-group diffusion model coupled with simplified burn-up equations is investigated for a one-dimensional burn-up drift wave problem, which is related to the recently developed concept of a so-called CANDLE reactor. This coupled system is solved successively by using the integrability (analytical solvability) in the one-group theory [5] under an initial assumption of a constant fraction of slow neutron flux. The multi-group effects are revealed by solving the slow part of the two-group diffusion equations. The method is convergent quickly, practically after one iteration. It is shown that the fraction of slow flux varies slightly in a solitary wave solution, however it has a significant quantitative impact on the solitary wave solution, in particular, on the wave length and drift speed.