In-Tae Kim

Current Status of Pyroprocessing Development at KAERI

Pyroprocessing technology has been actively developed at Korea Atomic Energy Research Institute (KAERI) to meet the necessity of addressing spent fuel management issue. This technology has advantages over aqueous process such as less proliferation risk, treatment of spent fuel with relatively high heat and radioactivity, and compact equipments. This paper describes the pyroprocessing technology development at KAERI from head-end process to waste treatment. The unit process with various scales has been tested to produce the design data associated with scale-up. Pyroprocess integrated inactive demonstration facility (PRIDE) was constructed at KAERI and it began test operation in 2012. The purpose of PRIDE is to test the process regarding unit process performance, remote operation of equipments, integration of unit processes, scale-up of process, process monitoring, argon environment system operation, and safeguards-related activities. The test of PRIDE will be promising for further pyroprocessing technology development.

Development of Tritium Technologies at KAERI

Abstract Tritium is formed by neutrons captured from deuterium. If left to accumulate, tritium oxide will become a hazard to the operating staff and public. The primary purpose of a Tritium Removal Facility (TRF) is to reduce tritium concentration in a heavy water moderator. In Korea, operation of a TRF commenced at the Wolsong Nuclear Power Site on July 26th, 2007. Nowadays, KAERI is developing a Very High Temperature Gas Cooled Reactor (VHTR). We have developed a tritium behavior analysis code for the VHTR. We also developed analytical methods for the measurement of food stuffs. Korea shared in the construction of the ITER fuel cycle plant with the EU, Japan, and the US, and is responsible for the supply of an SDS (Tritium Storage and Delivery System). We present the recent progress in the development of tritium storage technology, and safety features of the related system. KAERI has been developing tritium technologies related to the Wolsong TRF, HANARO, VHTR, and nuclear fusion fuel systems. We thus present details on the recent development progress of these tritium systems.

Modeling and simulation of pyroprocessing oxide reduction

Pyroprocessing operation modeling features complicated batch type operation, tangled material flow logic, handling many numbers of unit processes. Discrete event system (DES) modeling was applied to build an integrated operation model of which simulation showed that dynamic material flow was accomplished. In the model simulation, the amount of material transported through upstream and downstream in a process satisfied the mass balance equation for every batch operation. This study also analysed in detail an oxide reduction process and showed that every streams material flow could be exactly tracked under DES modeling environment.

Characteristics on the SAP-Based Wasteform Containing Radioactive Molten Salt Waste

This study investigated a unique wasteform containing molten salt wastes which are generated from the pyro-process for the spent fuel treatment. Using a conventional sol-gel process, SiO2 -Al2 O3 -P2 O5 (SAP) inorganic material reactive to metal chlorides were prepared. By using this inorganic composite, a monolithic wasteform were sucessfully fabricated via a simple process, reaction at 650°C and sintering at 1100°C. This unique wasteform should be qualified if it meets the requirements for final disposal. For this reasons, this paper characterized its chemical durability, physical properties, morphology and etc. In the SAP, there are three kinds of chains, Si-O-Si as a main chain, Si-O-Al as a side chain and Al-O-P/P-O-P as a reactive chain. Alkali metal chlorides were converted into metal aluminosilicate (Lix Alx Si1−x O2−x ) and metal phosphate (Li3 PO4 and Cs2 AlP3 O10 ) while alkali earth and rare earth chlorides were changed into only metal phosphates (Sr5 (PO4 )3 Cl and CePO4 ). These reaction products were compatible to borosilicate glasses which were functioned as a chemical binder for metal aluminosilicate and a physical binder for metal phosphates. By these phenomena, the wasteform was formed homogenously above μm scale. This would affect the leaching behaviors of each radionuclides or component of binder. The leach rates of Cs and Sr under the PCT-A test condition were about 10−3 g/m2 day. The physical properties (Cp, k, ρ, Hv, and etc) were very reasonable. Other leaching tests (ISO, MCC-1P) are on-going. From these results, it could be concluded that SAP can be considered as an effective stabilizer on metal chlorides and the method using SAP will give a chance to minimize the waste volume for the final disposal of salt wastes through further researches.© 2009 ASME

Separation of Rare Earth Precipitates From LiCl-KCl Eutectic Salts by a Distillation at a Reduced Pressure

Distillation and condensation characteristics of LiCl-KCl eutectic salts containing rare earth precipitates were investigated to separate the rare earth precipitates from the salts effectively. The distillation flux of the salts was increased by about 1,000 times by reducing the ambient pressure from 760 Torr to 0.5 Torr. The salt vapors were almost changed into salt lumps during a salt distillation at the ambient pressure of 0.5 Torr and they were collected in the condensed salt storage. However, fine salt particles were formed when the salt distillation was processed at 10 Torr and it is difficult for them to be recovered. Therefore, it is thought that a salt vacuum distillation and condensation should be processed to recover almost all of the vaporized salts at a pressure below 0.5 Torr.Copyright

Removal of alkaline-earth elements by a carbonate precipitation in a chloride molten salt

Separation of some alkaline-earth chlorides (Sr, Ba) was investigated by using carbonate injection method in LiCl-KCl eutectic and LiCl molten salts. The effects of the injected molar ratio of carbonate ([K2 (or Li2 )CO3 /Sr (or Ba)Cl2 ]) and the temperature (450–750 °C) on the conversion ratio of the Sr or Ba carbonate were determined. In addition, the form of the Sr and Ba carbonate resulting from the carbonation reaction with carbonates was identified via XRD and SEM-EDS analysis. In these experiments, the carbonate injection method can remove Sr and Ba chlorides effectively over 99% in both LiCl-KCl eutectic and LiCl molten salt conditions. When Sr and Ba were co-presented in the eutectic molten salt, they were carbonated in a form of Ba0.5 Sr0.3 CO3 . And when Sr was present in LiCl molten salt, it was carbonated in the form of SrCO3 . Carbonation ratio increased with a decreasing temperature and it was more favorable in the case of a K2 CO3 injection than that of Li2 CO3 . Based on this experiment, it is postulated that carbonate precipitation method has the potential for removing alkali-earth chlorides from LiCl-KCl eutectic and LiCl molten salts.Copyright