Solution reactor,as a new type of medical isotopes production reactor,is with many special features,such as flowing aqueous fissile solution,unstructured geometry,strong anisotropic scattering,and isotopes distillation.They all raise serious challenges for the fuel management calculation of solution reactors.An in-core fuel management calculation program package for solution reactors,called FMSR,is developed based on the DNTR code,a three-dimensional discrete ordinate nodal transport calculation code in triangular meshes.All results calculated by FMSR,including the distribution of power and void and cycle length and coefficients of reactivity,show that the program package can be used for the in-core fuel management calcula-tion of solution reactors as a trial.