1. CGNPC Uranium Resources Co. Ltd., Room 601, Building 5, Yard 16, Changxing Road, Fengtai District, Beijing 100072, P. R. China
2. China Nuclear Power Technology Research Institute, Baoshutai, Futian District, Shenzhen 518028, P. R. China
3. School of Automation, Beihang University, Building 5, Yard 16, Changxing Road, Fengtai District, Beijing 100072, P. R. China