• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.2
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• pp.207-215
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• 2020

The feasibility of rare earth (RE) removal process via oxidation reactions with UCl₃ was investigated using the HSC Chemistry code to reduce the concentrations of RE in transuranic (TRU) products. The composition and thermodynamic data of TRU and RE elements contained in the reference spent fuel were examined. The reactivity was evaluated by calculating equilibrium data considering oxidation reactions with UCl₃. Both RE removal rate and TRU recovery rate were evaluated for the two cases, wherein TRU products with different RE concentrations were used. When TRU products were reacted with UCl₃, selective oxidation was driven by the difference in the Gibbs free energy of each element. The calculation results imply that the TRU/RE ratio of the final product can be increased by removing RE elements while maintaining the maximum recovery rate of TRU, which is accomplished by controlling the amount of UCl₃ injected. Since the results of this study are based on thermodynamic equilibrium data, there are many limitations to apply to the actual process. However, it is expected to be used as an important data for the process design to supply the TRU product of pyroprocessing to SFR's fuel demanding low RE concentrations.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2016.05a
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• pp.277-278
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• 2016

• Annual Conference of KIPS
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• 2015.10a
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• pp.184-186
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• 2015

본 논문에서는 PTAM을 위한 새로운 분산 스트림 프로세싱 시스템을 제안한다. PTAM은 하나의 시스템에서 동작하도록 설계되었다. 이는 PTAM이 가지고 있는 한계점을 말해주는 부분인데, PTAM은 Bundle Adjustment의 계산 부하가 커지는 경우에 map을 구축하는데 있어 많은 시간과 리소스가 필요하다. 이에 하둡을 통해 계산 부하를 분산하고, PE(Processing Element)를 Xeon phi 시스템을 통해 동작되는 시스템을 제안한다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2263_2264
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• 2009

원자력은 나라의 기저전력을 책임지는 대표적인 발전소다. 시간이 지남에 따라 에너지 수요는 증가하지만 원자력 에너지의 연료인 우라늄은 고갈이 되어가고 있다. 그 해결책으로 고속로 기술에는 소듐 냉각 고속로, 건식처리 방법으로는 파이로프로세싱이 있다. 이 기술로 사용 후 원전연료를 재처리하여 불가 수 십년에 불가한 원전문제를 수 천년으로 늘릴 수 있다. 하지만 우리나라는 사용 후 원전연료에 대해 정책방향이 결정되지 않았으며, 지역단체, 환경단체 등의 단체에서의 반대도 만만치 않을 것이다. 원전연료 관리 정책이 결정되어 국가 에너지안보의 기틀을 마련해야 할 것이다.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.3
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• pp.181-186
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• 2015

It is necessary to develop an effective waste salt treatment technology for the minimization of radioactive waste generation from the pyroprocessing of spent nuclear fuel. For this reason, the separation characteristics of NdCl₃ from LiCl-KCl eutectic salt in a reactive distillation process using Li₂CO₃ or K₂CO₃ were observed. NdCl₃ was converted into oxychloride (NdOCl) or oxide (Nd₂O₃) in the reaction model between NdCl₃ and the carbonates using HSC-Chemistry, and this result was confirmed in the reactive distillation test of the LiCl-KCl-NdCl₃ system using the carbonates. Based on these results, the reactive distillation process conditions were determined to separate NdCl₃ into an oxide form (Nd₂O₃) which can be easily fabricated into a final waste form.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.1
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• pp.83-90
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• 2017

The pyroprocessing of spent nuclear fuel generates LiCl-KCl eutectic waste salt containing radioactive rare earth nuclides. It is necessary to develop a simple process for the treatment of LiCl-KCl eutectic waste in a hot-cell facility. In this study, capture and solidification of a rare earth nuclide (Nd) in LiCl-KCl eutectic salt using an inorganic composite with a $Li_2O-Al_2O_3-SiO_2-B_2O_3$ system was conducted to simplify the existing separation and solidification process of rare earth nuclides in LiCl-KCl eutectic waste salt from the pyroprocessing of spent nuclear fuel. More than 98wt% of Nd in LiCl-KCl eutectic salt was captured when the mass ratio of the composite was 0.67 over $NdCl_3$ in the eutectic salt. The content of $Nd_2O_3$ in the Nd captured-composite reached about 50wt%, and this composite was directly fabricated into a homogeneous and chemical resistant glass waste in a monolithic form. These results will be utilized in designing a process to simplify the existing separation and solidification process.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.2
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• pp.125-133
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• 2017

KAERI is conducting research on spent cladding hulls and additive metals to generate a solidification host matrix for the noble metal fission product waste in anode sludge from the electro-refining process to minimize the volume of waste that needs to be disposed of. In this study, alloy compositions Zr-17Cr, Zr-22Cr, and Zr-27Cr were prepared with or without eight noble metals representing fuel waste using induction melting. The microstructures of the resulting alloys were characterized and electrochemical corrosion tests were conducted to evaluate their corrosion characteristics. All the compositions had better corrosion characteristics than other Zr-based alloys that were evaluated for comparison. Analysis of the leach solution after the corrosion test of the Zr-22Cr-8NM specimen indicated that the noble metals were not leached during corrosion under 500 mV imposed voltage, which simulates a highly oxidizing disposal environment. The results of this study confirm that Zr-Cr based compositions will likely serve as chemically stable waste forms.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.4
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• pp.325-332
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• 2013

Pyroporcessing of spent nuclear fuel generates a considerable amount of LiCl-KCl eutectic waste salt containing radioactive rare earth (RE) chlorides. In this study, a series of processes, which consist of a phosphorylation/distillation process and a solidification process, were performed to minimize volume of the LiCl-KCl eutectic waste salt and solidify a residual waste into a stable form at a relatively low temperature. Over 99wt% of RE chlorides in LiCl-KCl eutectic salt was converted and separated into $REPO_4$ in the phosphorylation/distillation process using a mixture of $Li_3PO_4-K_3PO_4$. The separated $REPO_4$ was solidified into a homogeneous and fine-grained form at $1,050^{\circ}C$ using LIP(Lead Iron Phosphate) as a solidification agent. The final waste volume was reduced below about 10% through the series of the processes.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.1
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• pp.59-64
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• 2018

In case of high contents of rare earths in the LiCl-KCl salt, it is not easy to recover U and TRU metals as a usable resource form from LiCl-KCl eutectic salts generated from the pyroprocessing of spent nuclear fuel. In this study, a conversion of $UCl_3$ into an oxide form using $K_2CO_3$ and an electrodeposition of $NdCl_3$ into a metal form in $LiCl-KCl-UCl_3-NdCl_3$ system were conducted to resolve the problem. Before conducting the conversion, experimental conditions for the conversion were determined by performing a thermodynamic equilibrium calculation. In this study, almost all of $UCl_3$ disappeared in the LiCl-KCl salt when the injection of $K_2CO_3$ reached theoretical equivalent for the conversion, and then $NdCl_3$ was effectively electrodeposited as a metal form using liquid zinc cathode. After that, the LiCl-KCl salt became transparent, and uranium oxides were precipitated to the bottom of the LiCl-KCl salt. These results will be utilized in designing a process to separate U and rare earths in LiCl-KCl salt.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.3
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• pp.313-319
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• 2019

The A-KRS (Advanced Korean Reference Disposal System) is the disposal concept for pyroprocessed waste, which has been developed by the Korea Atomic Energy Research Institute. In this disposal concept, the amount of high-level radioactive waste is minimized using pyrochemical process, called pyroprocessing. The produced pyroprocessed waste is then solidified in the form of monazite ceramic. The final product of ceramic wastes will be disposed of in a deep geological repository. By the way, the decay heat is generated due to the radioactive decay of fission products and raises the temperature of buffer materials in the near field of radioactive waste repository. However, the buffer temperature must be kept below $100^{\circ}C$ according to the safety regulation. Usually, the temperature can be controlled by variation of the canister interdistance. However, KAERI has modelled thermal analysis under the boundary condition, where the waste canisters are in direct contact with each other. Therefore, a reliable temperature analysis in the disposal system may fail because of unknown thermal resistence values caused by the spatial gap between waste canisters. In the present work, we have performed thermal analyses considering the gap between heating elements and canisters at the beginning of canister loading into the radioactive waste repository. All thermal analyses were performed using the COMSOL software package.