This work was supported by the National Natural Science Foundation of China (Grant No. 71501068, 71371070, 71301069, 71071051), Research Project of LingDong Nuclear Power Co. Ltd. (Grant No. KR70543), Science and Technology Program of Hunan Province, China (Grant No. 2016WK2006), Scientific Research Program of Hunan Provincial Department of Education, China (Grant No. 15B062), Science and Technology Program of Hengyang, China (Grant No. 2016KG62), Research Study and Innovation Experiment Program for University Students of Hunan Province, China (Grant No. Xiangjiaotong[2016]283), Innovation Experiment Program for University Students of Hunan Institute of Technology, China (Grant No. H1539).