Local Structure Analysis of ZrN, and Dy_0.5Zr_0.5N surrogate materials for fast reactor nitride fuel

Abstract

ZrN is a possible candidate for the diluent material for the nitride fuels containing transuranium elements. Pellets of inert matrix material ZrN, and surrogate nitride fuel material (Dy_0.5Zr_0.5)N, are fabricated for the purpose of investigating crystal structure. Lattice parameters of (Dy_1-xZr_x)N followed the Vegards’s low, in spite of large lattice mismatch (～ 7 %) between DyN and ZrN. Local structure analysis was performed by X-ray absorption fine structure and atomic pair-distribution function methods. Although lattice parameter of Dy_0.5Zr_0.5N is larger than that of ZrN, Zr-N nearest neighbor bond distance of Dy_0.5Zr_0.5N is shorter than that of ZrN. The complex local structure of DyN and ZrN is related to the preferable effect of ZrN.