Evaluation of aluminum-clad spent nuclear fuel during drying and dry storage

Specimens were collected from irradiated non-fuel end box components of Advanced Test Reactor (ATR) fuel elements that are routinely removed at the end of reactor service life. These specimens represent surface conditions and adsorbed water on aluminum clad fuel before drying. Tools and procedures have been developed for remote material sampling from ATR elements from (non-sealed) dry storage at the Irradiated Fuel Storage Facility (IFSF). This follow-on effort has been scheduled and targets ATR elements that had been stored in poor quality water and have had the longest residence time at IFSF. This activity is to be performed in conjunction with scheduled fuel handling activities. The sampling plan is to acquire pieces from the fuel assembly side plate corners and to scrape surface oxide from the exposed outer plate. Multiple analytical techniques were used to assess the chemical composition and morphology of surface oxides. A separate, simultaneous effort is progressing to generate surrogate oxyhydroxide materials for use in several rigorously controlled experiments. Consistently produced surrogate can then be used to assess remote sampling practices and validate performance models under relevant constraints. These efforts will substantiate cladding performance and decisions regarding drying and packaging over a range of life-cycle conditions.