• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11a
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• pp.143-152
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• 2005

There certainly exists the radioactive inventory that exceeds the waste acceptance criteria for final disposal of the low and intermediate-level radioactive waste. In this paper, current disposal status of the long-lived radioactive waste in several nations are summarized and the basic procedures for disposal approach are suggested. With this suggestion, intensive discussion and research activities can hopefully be launched to set down the possible resolutions to dispose of the long-lived radioactive waste.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.3
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• pp.359-367
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• 2018

Long-lived Small Modular Reactors are being promoted as an innovative way of catering to emerging markets and isolated regions. They can be operated continuously for decades without requiring additional fuel. A novel configuration of long-lived reactor core employs a mixed neutron spectrum, providing an improvement in nonproliferation metrics and in safety characteristics. Starting with a base sodium reactor design, moderating material is inserted in outer core assemblies to modify the fast spectrum. The assemblies are shuffled once during core lifetime to ensure that every fuel rod is exposed to the thermalized spectrum. The Mixed Spectrum Reactor is able to maintain a core lifetime over two decades while ensuring the plutonium it breeds is below the weapon-grade limit at the fuel discharge. The main drawbacks of the design are higher front-end fuel cycle costs and a 58% increase in core volume, although it is alleviated to some extent by a 48% higher power output.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.11a
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• pp.289-290
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• 2018

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.2
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• pp.231-241
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• 2022

Several countries, including Korea, are considering the direct disposal of spent nuclear fuels. The radiological safety assessment results published after a geological repository closure indicate that the instant release is the main radiation source rather than the congruent release. Three Safety Case reports recently published were reviewed and the IRF values of seven long-lived radionuclides, including relevant experimental results, were compared. According to the literature review, the IRF values of both the CANDU and low burnup PWR spent fuel have been experimentally measured and used reasonably. In particular, the IRF values of volatile long-lived nuclides, such as ¹²⁹I and ¹³⁵Cs, were estimated from the FGR value. Because experimental leaching data regarding high burnup spent nuclear fuels are extremely scarce, a mathematical modelling approach proposed by Johnson and McGinnes was successfully applied to the domestic high burnup PWR spent nuclear fuel to derive the IRF values of iodine and cesium. The best estimate of the IRF was 5.5% at a discharge burnup of 55 GWd tHM^-1.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.4
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• pp.489-502
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• 2023

This article presents the crucial role played by the French underground research laboratory (URL) in initiating the deep geological repository project Cigéo. In January 2023, Andra finalized the license application for the initial construction of Cigéo. Depending on Government's decision, the construction of Cigéo may be authorized around 2027. Cigéo is the result of a National program, launched in 1991, aiming to safely manage high-level and intermediate level long-lived radioactive wastes. This National program is based on four principles: 1) excellent science and technical knowledge, 2) safety and security as primary goals for waste management, 3) high requirements for environment protection, 4) transparent and open-public exchanges preceding the democratic decisions and orientations by the Parliament. The research and development (R&D) activities carried out in the URL supported the design and the safety demonstration of the Cigéo project. Moreover, running the URL has provided an opportunity to gain practical experience with regard to the security of underground operations, assessment of environmental impacts, and involvement of the public in the preparation of decisions. The practices implemented have helped gradually build confidence in the Cigéo project.

• Nuclear Engineering and Technology
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• v.38 no.6
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• pp.459-482
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• 2006

A geochemical approach to the long-term safety of waste disposal is discussed in connection with the significance of actinides, which shall deliver the major radioactivity inventory subsequent to the relatively short-term decay of fission products. Every power reactor generates transuranic (TRU) elements: plutonium and minor actinides (Np, Am, Cm), which consist chiefly of long-lived nuclides emitting alpha radiation. The amount of TRU actinides generated in a fuel life period is found to be relatively small (about 1 wt% or less in spent fuel) but their radioactivity persists many hundred thousands years. Geological confinement of waste containing TRU actinides demands, as a result, fundamental knowledge on the geochemical behavior of actinides in the repository environment for a long period of time. Appraisal of the scientific progress in this subject area is the main objective of the present paper. Following the introductory discussion on natural radioactivities, the nuclear fuel cycle is briefly brought up with reference to actinide generation and waste disposal. As the long-term disposal safety concerns inevitably with actinides, the significance of the aquatic actinide chemistry is summarized in two parts: the fundamental properties relevant to their aquatic behavior and the geochemical reactions in nanoscopic scale. The constrained space of writing allows discussion on some examples only, for which topics of the primary concern are selected, e.g. apparent solubility and colloid generation, colloid-facilitated migration, notable speciation of such processes, etc. Discussion is summed up to end with how to make a geochemical approach available for the long-term disposal safety of nuclear waste or for the performance assessment (PA) as known generally.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.02a
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• pp.150-164
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• 2004

According to the Korean long-term plan for nuclear technology development, KAERI is conducting a few R&D projects related to the proliferation-resistant back-end fuel cycle. The R&D activities for the back-end fuel cycle are reviewed in this work, especially focusing on the study of the partitioning and transmutation(P&T) of long-lived radionuclides. The P&T study is currently being carried out in order to develop key technologies in the areas of partitioning and transmutation. The partitioning study is based on the development of pyroprocessing such as electrorefining and electrowinning because they can be adopted as proliferation-resistant technologies in the fuel cycle. In this study, various behaviors of the electrodeposition of uranium and rare earth elements in the LiCl-KCl electrorefining system have been examined through fundamental experimental work. As for the transmutation system, KAERI is studying the HYPER (HYbrid Power Extraction Reactor), a kind of subcritical reactor which will be connected with a proton accelerator. Up to now, a conceptual study has been carried out for the major elemental systems of the subcritical reactor such as core, transuranic fuel, long-lived fission product target, and the Pb-Bi cooling system, etc. In order to enhance the transmutation efficiency of the transuranic elements as well as to strengthen the reactor safety, the reactor core was optimized by determining its most suitable subcriticality, the ratio of height/diameter, and by introducing the concepts of optimum core configuration with a transuranic enrichment as well as a scattered reloading of the fuel assemblies.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.339-339
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• 2004

원자로를 이용하여 장수명핵종(long lived nucleus)을 소멸처리하는 과정에서 초우라늄(TRU, transuranium)과 희토류(RE, rare earth) 금속에 포함되어 있는 소량의 핵분열성(fissile) 물질인 우라늄을 제거할 필요가 있다. 본 실험은 LiCl-KCl 용융염계에서 전해제련법(Electrowinning)을 이용하여 용융염욕에 존재하는 우라늄을 제거하기 위하여 필요한 Cd-Li 양전극 물질을 제조하였고, 제조된 금속을 이용하여 우라늄 및 란탄족(Dy, Ce, Y, Nd, Gd) 금속의 환원 특성을 파악하였다.(중략)

• Tunnel and Underground Space
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• v.1
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• pp.32-38
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• 1991

9 nuclear power plants are presently in operation in Korea. They produce radioactive waste of which the most long-lived radioactive elements need to be safely stored for hundreds of thousands of years, isolated from humanity and the environment. The safe disposal of high level radioactive waste in mined cavities requires knowledge of the mechanical. thermal and fluid flow characteristics of rock as perturbed by a thermal pulse The literature review was performed to assemble data on the following properties: modulus tensile strength compressive strength thermal expansion specific heat, thermal conductivity thermal diffusivity and permeability.

• Nuclear Engineering and Technology
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• v.42 no.1
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• pp.1-8
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• 2010

Geological disposal is designed to provide safe containment of radioactive waste for very long times, with the containment provided by a combination of engineered and geological barriers. In the extreme long term, after many thousands of years or longer, residual amounts of long-lived radionulides such as Cl-36, but also radionuclides in the natural decay chains, may be released into the environment normally accessed and used by humans, termed here, the biosphere. It is necessary to ensure that any such releases meet radiation protection objectives through the development of a safety case, which will include assessment of radiation doses to humans. The design of such dose calculations over such long timeframes is not straightforward, because of the range of potentially relevant assumptions which could be made, concerning environmental change and changes in human behavior. These conceptual uncertainties are additional to those that more typically arise, for example, in the assessment of present day situations, but which also have to be addressed. The issue has therefore been subject to international cooperation for many years. This paper summarizes the evolution and results of that collaboration leading up to the present day, taking account of developments in international recommendations on radiation protection objectives and the more recent greater focus on preparation of site specific safety cases.