The calcination process in uranium dioxide production is a crucial link that affects the indicators (tetravalent uranium) of uranium dioxide products. The mechanism of decomposition and reduction of AUC to produce UO2 is discussed, and the main factors and control measures affecting the tetravalent uranium content in the product are identified. It is found that the oxidation of UO2 leading to unacceptable tetravalent uranium levels cannot be directly measured but is a significant factor. Common reasons for tetravalent uranium levels being unacceptable, such as material abnormalities, equipment failures, and abnormal operations, are summarized. Equipment failures and abnormal operations are particularly prone to causing the oxidation of UO2 leading to unacceptable tetravalent uranium levels. Therefore, the weak points in the quality of natural uranium dioxide product mainly lie in equipment failures during the calcination of AUC and abnormal operations in the cooling process.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |