Abstract
The variant of the gamma albedo method is proposed for the radioisotope express control of coal ash content, which ensures the satisfactory accuracy under conditions of variable elemental composition of coal. It is shown that the integral intensity of the secondary (scattered and fluorescent) radiation weakened by filter of certain thickness is a univocal index of coal ash content. The analytical model for the optimization of the secondary radiation filtration parameters is developed. The utility value of the weakening filter is determined as function of ash content and composition of coal.