Densification of matrix graphite for spherical fuel elements used in molten salt reactor via addition of green pitch coke
Zhao He, Hongchao Zhao, Jinliang Song, Xiaohui Guo, Zhanjun Liu, Yajuan Zhong, T.J. Marrow
Abstract
Green pitch coke with an average particle size of 2 μm was adopted as densifier and added to the raw materials of conventional A3-3 matrix graphite (MG) to prepare modified A3-3 matrix graphite (MMG) by the quasi-isostatic molding method. The structure, mechanical and thermal properties were assessed. Compared with MG, MMG had a more compact structure, and exhibited improved properties of higher mechanical strength, higher thermal conductivity and better molten salt barrier performance. Notably, under the same infiltration pressure of 5 atm, the fluoride salt occupation of MMG was only 0.26 wt%, whereas it was 15.82 wt% for MG. The densification effect of green pitch coke endowed MMG with improved properties for potential use in the spherical fuel elements of molten salt reactor.