Due to the saturation of the on-site storage capacity of spent nuclear fuel within a few years, dry storage facility should be introduced. However, it is unclear when to start operating the dry storage facility, so in case of Kori Unit 1, which is being decommissioning, the spent fuel must be stored in the spent fuel pool of another power plant. In addition, in the case of damaged fuel, it is impossible to transfer and store it with general handling methods. Therefore, a damaged fuel canister (DFC) should be able to handle damaged or failed fuel as intact fuel, and both wet and dry storage should be possible. The canister developed by Korea Hydro & Nuclear Power is designed to satisfy criticality, shielding, cooling performance, and structural integrity in accordance with NUREG-1536 and 2215. In addition, it can be handled as existing fuel handling devices rather than new handling tools. Fastening of the DFC lid and body in the spent fuel pool is possible with a hexagonal socket wrench, one of the fuel repair tools. And it is designed to facilitate visual identification of whether it is fastenedor not. The lifting method for transferring DFC to another facility is the same as the nuclear fuel lifting method. And a unique sealing and mesh structure of the lid and body is devised to completely block leakage of nuclear fuel fragments of 0.2 mm or more during vacuum drying for dry storage. The usability of DFC has been verified through test operation of the prototype, and it will be manufactured before discharging spent fuel for the decommissioning of Kori Unit 1.

Interests in molten salt reactor (MSR) using a fast spectrum (FS) have been increased not only for having a high power density but for burning the high-level waste generated from nuclear power plants. For developing the FS-MSR technologies, chloride-based fuels are considered due to the advantage of higher solubility of actinides and lanthanides over fluoride-based salts. Despite significant progress in development of MSR technology, the manufacturing technology for production of the fuel is still insufficiently understood. One of the option to prepare the MSR fuel is to use products from pyroprocessing where oxide form of spent nuclear fuel is reduced into metal form and useful elements can be collected via electrochemical methods in molten salt system at high temperature. In order to chlorinate the products into chloride form, previous study used NH4Cl to chlorinate U metal into UCl3 in an airtight reactor. It was found that the U metal was completely chlorinated into chloride forms; however, impurities generated by the reaction of NH4Cl and reactor wall were found in the product. Therefore, in this work, the air tight reactor was re-deigned to avoid the reaction of reactor wall by insertion of Al2O3 crucible inside of the reactor. In addition, the reactor size was increased to produce UCl3 over 100 g. Using the newly designed reactor, U metal chlorination experiments using NH4Cl chlorinating agent were performed to confirm the optimal experimental conditions. The detailed results will be further discussed.

The effect of Li2O addition on precipitation behavior of uranium in LiCl-KCl-UCl3 has been investigated in this study. 99.99% LiCl-KCl eutectic salt is mixed with 10wt% UCl3 chips at 550°C in the Pyrex tube in argon atmosphere glove box, with 10 ppm O2 and 1 ppm H2O. Then, Li2O chunks are added in mixed LiCl-KCl-UCl3 and the system has been cooled down to room temperature for 10 hours to form enough UO2 particles in the salt. The solid salt has been taken out from the glove box, and cut into three sections (top, middle and bottom) by low-speed saw for further microscopic analysis. Three pieces of solid salt are dissolved in deionized water at room temperature and the solution is filtered by a filter paper to collect non-dissolved particles. The filter paper with particles is baked in vacuum oven at 120°C for 6 hours to evaporate remaining moisture from the filter paper. Further analysis was performed for the powder remaining on the filter paper, and periphery of the powder (cake) on the filter paper. Scanning electron microscopy (SEM), electron diffraction spectroscopy (EDS), and X-ray powder diffraction (XRD) are adopted to analysis the characteristic of the particles. From SEM analysis, the powders are consisted of small particles which have 5 to 10 m diameter, and EDS analysis shows they are likely UO2 with 23 at. % of uranium and 77 at. % oxygen. Cake is also analyzed by SEM and EDS, and needle like structures are widely observed on the particle. The length of needle is distributed from 5 to 20 m, and it has 6 to 10 at. % of chlorine, which are not fully dissolved into deionized water at room temperature. From XRD analysis, the particles show the peak position of UO2, and the result is well matched with the SEM-EDS results. We are planning to add more Li2O in the system for fully reacting uranium in UCl3, and compare the results to find the effect of Li2O concentration on UO2 precipitation.

B4C/Al composite is mainly used for neutron absorbing materials, which is one of the components of equipment that manages spent nuclear fuel. There are various processes for manufacturing neutron absorbing materials, but most of them are based on the powder metallurgy. In this study, B4C/Al composite in which the reinforcement was uniformly dispersed was manufactured by using the stir casting process. The microstructure, thermal neutron absorption rate, mechanical properties and dispersibility of the reinforcement of the prepared B4C/Al composite were analyzed.

Separation of high heat generating-radioactive isotopes from spent nuclear fuel is an important issue because it can reduce the final disposal area. As one of the technologies that can selectively separate only high heat generating-radioactive isotopes without dissolving spent fuel, the methods using molten salt have recently attracted attention. Although studies on chemical changes of Sr oxides in molten salts have been reported, they have limitation in that alternative oxide reagents rather than oxide fuel were used. In this study, the separation behaviors of Sr from simulated oxide fuel using various molten salts were investigated. A powder type containing 95.7wt% of U and 0.123wt% of Sr was used as the simulated oxide fuel. LiCl, LiCl-CaCl2, MgCl2, LiCl-KCl-MgCl2 and NaCl-MgCl2 were used as molten chloride salts. The separation of Sr from the simulated oxide fuel was conducted by loading it in porous alumina basket and immersing it in a salt. The concentration of Sr in the salt was measured by ICP analysis after sampling the salt outside the basket using dip-stick technique. The separation efficiencies of Sr from simulated oxide fuel using the salts were compared. Furthermore, the causes of their separation efficiency were systematically investigated.

The guidelines for cyber security regulations at domestic and foreign nuclear facilities, such as KINAC/RS-015, NRC’s RG5.71 and NEI 13-10, require the establishment of security measures to maintain the integrity of critical digital assets (CDAs) and protect them as threats to the supply process. According to the requirements, cyber security requirements shall be reflected in purchase requirements from the time of introduction of CDAs, and it shall also be verified whether cyber security security measures were properly applied before introduction. Domestic licensees apply measures to control the supply chain in the nuclear safety sector to cyber security policies. The safety sector supply chain control policy has areas that functionally overlap with the requirements of cyber security regulations, so regulatory guidelines in the safety sector can be applied. However, since most of the emergency preparedness and physical protection functions introduce digital commercial products, there is a limit to applying the control of the supply chain in the safety field as it is. It is necessary to apply supply chain control operator policies, procedures, and purchase requirements for each SSEP function, or to establish cyber security integrated supply chain control requirements. In this paper, based on the licensee’s current supply chain control policy, the cyber security regulation plan for supply chain control according to the SSEP (Safety-Security-Emergency Preparedness) function of CDAs is considered.