Current Status of Spent Fast Reactor Fuel Reprocessing and Waste Treatment in Various Countries: Republic of Korea

KAERI has been developing an advanced spent fuel conditioning process (ACP) since 1997, based on a pyrochemical process, which has a number of potential advantages, such as compactness, simplicity and low cost. The ACP reduces the volume, radiotoxicity and heat load of the spent oxide fuels discharged from the current fleet of commercial PWRs and eventually creates a facile form of a metallic ingot for disposal. An electrolytic reduction process has been developed as a key unit of the ACP, which consists of several steps, including voloxidation, electrolytic reduction and smelting. In the ACP concept, the air oxidation, called voloxidation, enables the pulverizing of spent fuel, enhancing the electrolytic reduction rate due to the surface area increase of spent fuel. The spent oxide fuel, which is voloxidized in advance, is converted to metallic form by an electrochemical method in LiCl-Li2O molten salt. The produced metal is smelted to be prepared in a metal ingot form. Gaseous FPs, such as I2, Kr and Xe, are released during the voloxidation step. In addition, salt-soluble FPs, such as Cs, Sr, etc., are dissolved and removed from the SNF during an electrolytic reduction step. A facility for demonstration of the ACP process at 20 kg HM/batch scale has been built. KAERI is also carrying out another R and D project on P and T of LLRNs, focusing on the development of a pyroprocess based on electro-refining of actinides. In the electro-refining process, most of the actinides as well as FPs are electrochemically dissolved from the anode into molten LiCl-KCl salt, and then uranium and TRU elements are selectively recovered by using two types of cathodes. As part of the pyrochemical partitioning studies for P and T purposes, various electrochemical experiments using a solid cathode and a liquid cadmium cathode have been carried out to investigate the electrochemical behaviour of uranium and rare earth elements in the electro-refining system. On the basis of this fundamental study, electro-refiners of 100 g U/batch and 1 kg U/batch were developed successfully in 2003 and 2006, respectively. Currently, KAERI's unique continuous high throughput electro-refiner is under development to embody a capacity of 20 kg U/batch. The continuous concept in this refiner was realized by means of a graphite cathode system. For the recycling of a used salt during the pyroprocess, batch type ion exchange technology has been developed to remove the radioactive nuclides, such as Cs and Sr, in a waste salt. Especially, the final waste volume may be drastically decreased by selective removal of FP nuclides in the waste salt through an oxidation/precipitation reaction. KAERI has established the basic concepts of waste salt minimization by recycling of the refined salt. In December 2008, the Korea Atomic Energy Commission approved a long term R and D plan for the development of a sodium FR and pyroprocessing technology in order to utilize the benefits of nuclear energy and manage the burden of spent fuel in a proliferation resistant manner. The main efforts for developing pyroprocessing are directed at the electrolytic reduction of oxide fuel and electro-refining, targeting the reduction of the volume, heat load and toxicity of the spent fuel, and application to sodium FR systems as the recycling and transmutation methods for closing the fuel cycle. Future technology development of a pyroprocess includes four steps: development of the key technologies in the first step (2007-2009), demonstration and verification of an engineering scale facility (2010-2016), installation of a demonstration facility (2017-2025) and operation of the pyroprocessing facility after 2026