As a method for chlorinating spent nuclear fuel, a method of using ZrCl4 in high-temperature molten salt is known. However, ZrCl4 has a sublimation property that vaporizes at a temperature similar to the melting temperature of molten salt. Since solubility of ZrCl4 in molten salt is very low, it is difficult to dissolve a large amount of ZrCl4 in molten salt. However, once ZrCl4 can be dissolved together with the molten salt, it remains in the molten salt without vaporizing. That is, it is known that when vaporized ZrCl4 reacts with molten salt in a sealed reactor, it dissolves into the molten salt, and ZrCl4 above the solubility remains in the molten salt in the form of M2ZrCl6. Here, M represents an alkali element. Therefore, in this study, a flange-type sealed reactor was fabricated to dissolve a large amount of ZrCl4 in LiCl-KCl salt, and LiCl-KCl salt in which ZrCl4 was dissolved as K2ZrCl6 was prepared. LiCl-KCl, KCl, and ZrCl4 salts were charged into alumina crucibles and placed in a sealed reactor. The reactor was heated to 500°C and the reaction time was about 20 hours. The temperature of the reactor surface was about 480°C. After completion of the reactions, each crucible was recovered from the inside of the reactor. All of the ZrCl4 vaporized and there was no residue in the crucible. Both KCl and LiCl-KCl salts appear to have dissolved and then cooled, with respective weight gains. XRD analysis was performed to observe the structure of the recovered salts, and ICP analysis was performed to measure the Zr element content in each salt. As a result of XRD analysis, the structure of K2ZrCl6 was found in the KCl salt, but not in the LiCl-KCl salt. As a results of ICP analysis, it was found that the LiCl-KCl salt contained about 33wt% of ZrCl4, and about 25wt% was dissolved in the KCl salt. In other words, it was shown that ZrCl4 above the solubility can be dissolved in the LiCl-KCl molten salt.

• Seungwoo Paek(Korea Atomic Energy Research Institute (KAERI)) Corresponding author
• Dalsung Yoon(Korea Atomic Energy Research Institute (KAERI))
• Sang Kwon Lee(Korea Atomic Energy Research Institute (KAERI))
• Chang Hwa Lee(Korea Atomic Energy Research Institute (KAERI))