Application of melt and refining procedures in the CANDLE reactor concept

• The melt refining (MR) method was applied to solve fuel integrity problem in CANDLE.
• The fuel element was assumed cut into several melt-and-refining-regions (MRRs).
• Nuclide composition was homogenized in the 9 MRR, 5 MRR and 3 MRR at each cycle.
• The CANDLE burning can be achieve if a proper number of MRR is selected.
• The fuel volume fraction can be reduced if fission products are removed in MR.

The application of melt and refining procedures has demonstrated great potential to solve the fuel integrity problem in the high-burnup condition of CANDLE reactors. However, if the melt and refining procedures are applied during operation, the reactor might lose all the nuclide distribution in the fuel pins and CANDLE burning becomes impossible to achieve. In this study, the application of melt and refining was simulated in two cases to overcome the cladding limitation at ⩾200 dpa. It became clear that if the number of axial regions for the melt and refining procedure is chosen properly, CANDLE burning is possible to achieve even if each region is homogenized by the procedure. In addition, the fission products released by the melt and refining procedure increase the burnup performance of the CANDLE core remarkably. It is also possible to improve the engineering design by reducing the fuel volume fraction to a minimum at 48%.