[en] Nuclear Transmutation Energy Research Center of Korea(NUTRECK) established by Ministry of Commerce in 2002. LBE-based transmutation technology are PEACER viability confirmed, further design improvements planned, 3D CAD/SIVR approach proves instrumental and HELIOS began safety and materials tests. ASIAN LFR Collaborations are transmutation and hydrogen system, collaborative approach towards viable options, system design R and D and materials R and D

[en] The evolving technology with accelerator-based energy production and waste transmutation presents a challenge for materials development R and D. In this paper the proposed designs of the nuclear energy system and fuel cycle concepts are reviewed with the focus on the structural materials issues that have potential for compromising the system economic competitiveness over contemporary fission power reactor systems. Radiation damage of proton beam window and structural materials for target system and fuels, and corrosion attack by liquid lead coolant and molten salt have been evaluated as the most challenging materials issues. The area and direction of further developments are suggested as a preliminary guide for R and D planning. (author)

[en] REFIN model is applied to analyze a series of experiments that had been conducted by Tomczuk, et al. at Argonne National Laboratory (ANL) in the U.S.A.. Predicted results from REFIN model for the electrorefining experiment are compared with the published experimental results. It is demonstrated that REFIN model can predict faradic current of each element and electrochemical potential as a function of time over the entire campaign of the electrorefining experiment. The elemental concentration changes agree with the experimental results well. Elemental concentration changes during an open-circuit equilibration period are revealed to suggest that the electrorefining process could not be adequately described by the equilibrium model often applied for an electrode surface. Surface potential drop is changed according to equilibrium potential of chemical species with high activity in liquid metal

[en] The applicability of nickel-plating to EAC problems in CRDM nozzle was estimated in the light of electrochemical aspect. The passive film growth law for nickel was improved to include oxide dissolution rate improving conventional point defect model to explain retarded passivation of plated nickel in PWR primary side water environment and compared with experimental data. According to this model, oxide growth and passivation current is closely related with oxide dissolution rate because steady state is made only if oxide formation and oxide destruction rate are same, from which oxide dissolution rate constant, k_s, was quantitatively obtained utilizing experimental data. Commonly observed current-time behavior, i∝t^m ,where m is different from 1 or 0.5, for passive film formation can be accounted for by virtue of enhanced oxide dissolution in high temperature aqueous environment

[en] This study is basically consisted of steps of methodology to evaluate the flawed piping under beyond design basis earthquake. The objective of this study is to suggest the methodology to estimate the allowable flaw size with consideration over design basis earthquake using FEM with ASME code criteria. This could be applied in various flaw and pipe circumstances. The next step should be obviously actual analysis with real pipe model and date. In the overall steps, elaborate finite element analysis to estimate of the seismic load is needed. Further study pursues the flaw evaluation for the piping in OPR 1000. Integrity of plant piping has critical importance to the safety of nuclear power plants. So there are some non-destructive examination methods for to detect the flaws, but they have to wait for reactor shutdown, around 10 years. And there is an allowable size criterion of the crack to judge the continuation operation of the plant. But in practice, many cracks have been detected whose depth is larger than the code allowable size especially in weldment of the pipes. Considering the crack growth rate in PWR operation environment, the cracks in dissimilar welds could grows unusually fast especially during earthquake. After Fukushima accident, the riskiness due to the unexpected seismic events has been well known. Design basis earthquake of the some Korean old plants is 0.2g, but in the latest stress tests for the old plants which are the follow-up measures, 0.3g seismic load is assumed to secure more high confidence of the plant. In this point of time, seismic consideration on the flaw evaluation is also needed

[en] The lower head of the reactor pressure vessel (RPV) can be subjected to significant thermal and pressure loads in the event of a core meltdown accident. For the detailed understanding of its bahavior, a real scale experiment of RPV creep with prototype material, namley low alloy steel, is in demand. But it is highly difficult to perform because of very high heat flux and pressure. If we can replace the real test of the prototype material using dimensional analysis with a model material that possesses constitutive similarity but has low melting temperatrue and mechanical strength, the experiment can be significantly simplified and less expensive. From the mathematical structure of the constitutive equation for classical viscoplasticity, a simple rheological model was derived. The model explains the time dependent mechanical behavior of RPV creep. The creep equation was nondimensionalized using the dimensionless group of variables. By adopting lead (Pb) as a model material, heat flux and pressure conditions of the model experiment was defined. Finite element analyses showed adequate agreement between prototype and model systems for the time dependent deformation behavior on nondimensional coordinates such that this novel approach can by used under the scaled temperature/pressure conditions to represent creep deformation behavior of prototype RPV

[en] In spite of the Fukushima disaster, strong demands for nuclear energy still exist and are increasing especially in many emerging states. With a steadily growing civilian nuclear power industry in the world, the need for a stable supply of nuclear fuels (front-end fuel cycle) and safe disposal of spent fuels (back-end fuel cycle) is intensifying. However, the related nuclear technologies, such as uranium enrichment and spent fuel reprocessing, have often been used for the clandestine nuclear weapon even under various national and international control mechanisms of today's nuclear non-proliferation regime. Eliminating the risk of proliferation and terrorism through facilitating peaceful and environment friendly uses of nuclear energy, is the primary objective of the multinational nuclear approach (MNA). International efforts for the implementation of MNA for regions of emerging economies can be as important as reinforcing the current non-proliferation regime. In order to develop more detailed scenarios for implementing MNA proposals, the significant features of MNA proposals through literature review were examined. In addition, the coverage of MNA in the fuel cycle is defined by considering current issues and necessities, and evaluated with important criteria: proliferation-resistance, environmental-friendliness, accident-tolerance, continuity and economy. In this process, a proposal for MNA on the back-end fuel cycle is introduced as a schematic structure. (authors)

[en] Electronic structure of the metal/passive film/solution system was modeled based on the Point Defect Model and the work of Armstrong et al and its characteristics was investigated by potentiodynamic polarization and Electrochemical Impedance Spectroscopy(EIS) measurement for a commercial alloy 600 at room temperature. The modeling of metal/passive film/solution system showed the system could be described by well developed equivalent circuit. From EIS measurement of the passive film on Alloy 600 diffusivity of oxygen vacancies was estimated to 2.0724 x 10^-14 cm²/sec

[en] In the TMI-2 accident, approximately twenty (20) tons of molten core material drained into the lower plenum. Early advanced light water reactor (LWR) designs assumed a lower head failure and incorporated various measures for ex-vessel accident mitigation. However, one of the major findings from the TMI-2 Vessel Investigation Project was that one part of the reactor lower head wall estimated to have attained a temperature of 1100 .deg. C for about 30 minutes has seemingly experienced a comparatively rapid cooldown with no major threat to the vessel integrity. In this regard, recent empirical and analytical studies have shifted interests to such in-vessel retention designs or strategies as reactor cavity flooding, in-vessel flooding and engineered gap cooling of the vessel. Accurate thermohydrodynamic and creep deformation modeling and rupture prediction are the key to the success in developing practically useful in-vessel accident/risk management strategies. As an advanced in-vessel design concept, this work presents the COrium Attack Syndrome Immunization Structures (COASIS) that are being developed as prospective in-vessel retention devices for a next-generation LWR in concert with existing ex-vessel management measures. Both the engineered gap structures in-vessel (COASISI) and ex-vessel (COASISO) are demonstrated to maintain effective heat transfer geometry during molten core debris attack when applied to the Korean Standard Nuclear Powre Plant (KSNPP) reactor. The likelihood of lower head creep rupture during a severe accident is found to be significantly suppressed by the COASIS options

[en] J-R test based on elastic plastic fracture mechanics, has been widely used in safety assessment of pressure vessel and pipe in nuclear power plant. DC-potential drop (DCPD) method has been employed by some researchers for use in dynamic loading J-R test to simulate seismic loading effect. But, the method has the significant shortcoming with ferromagnetic materials due to ferro-electric noise. The normalization method which was accepted to American Society for Testing and Materials (ASTM) standard test method in 2001, is a very useful method to determine J-R curve under dynamic loading or other difficult conditions, because it does not need any additional equipment or complicate loading sequences like electric current or unloading. But, in the normalization round robin under static loading condition, some unreliable results were shown which are larger deviation and greater JIc's than the unloading compliance method. In this study, the source of the large deviation and differences of current normalization procedure was explored, and the modified normalization procedure was developed to improve the reliability