Korea Institute of Nuclear Nonproliferation and Control

Korea, South Korea

Korea Institute of Nuclear Nonproliferation and Control

Korea, South Korea
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Lee S.,Kyung Hee University | Jin K.,Kyung Hee University | Kim J.,Korea Institute of Nuclear Nonproliferation and Control | Heo G.,Kyung Hee University
Journal of Radioanalytical and Nuclear Chemistry | Year: 2017

The purpose of this study is to categorize the type of spent nuclear fuels using simulation data-based classification methods. Considering the practical conditions making the full analysis of radioactive nuclides difficult, the classification methods were designed to be robust to noise and missing information. The strength and weakness of three classifiers, linear discriminant analysis, quadratic discriminant analysis and support vector classification were compared, which is developed by the history information such as burnup, enrichment, and cooling type generated from ORIGEN-ARP upon fuel assembly types. Auto-Associative Kernel Regression improved outlier management as a pre-processing technique. © 2017 Akadémiai Kiadó, Budapest, Hungary

Borrelli R.A.,University of Idaho | Ahn J.,University of California at Berkeley | Hwang Y.,Korea Institute of Nuclear Nonproliferation and Control
Nuclear Technology | Year: 2017

Many nations are expanding or initiating nuclear energy programs as part of a national energy portfolio. Transitioning to advanced nuclear energy systems improves sustainability and promotes energy independence. These advanced nuclear energy systems also must be shown to enhance safety, safeguards, and security in order to be realistically deployed. This is of particular concern to non-nuclear weapons states, to assure compliance with International Atomic Energy Agency treaty obligations. Consequently, the relatively new research area of safeguardability addresses how to integrate goals for safety, safeguards, and security as part of a design strategy for an advanced fuel cycle. This paper presents an overall set of principles that form the foundation of a comprehensive safeguardability methodology, including the quantitative modeling studies derived therein. Results show an approach for characterizing used fuel, functional components to engineering design for nuclear materials handling facilities, and repository analysis. We conclude with an argument for the necessity of an integrative, systems assessment approach to the safeguardability of an advanced fuel cycle. © 2017 American Nuclear Society.

Lee C.,Ulsan National Institute of Science and Technology | Choi S.,Ulsan National Institute of Science and Technology | Kim W.J.,Korea Institute of Nuclear Nonproliferation and Control | Kim M.S.,Korea Institute of Nuclear Nonproliferation and Control | Jeong Y.H.,Korea Institute of Nuclear Nonproliferation and Control
Nuclear Engineering and Design | Year: 2017

The physical protection of nuclear materials is a significant regulatory requirement to prevent and impede the theft of materials suitable for nuclear explosives. These materials need to be systematically categorized based on their characteristics and risk. The categorization methods are evolving to reflect new issues. One of which is new types of materials from new technologies. We first reviews existing categorization methods for degrees of attractiveness, category levels, discount factor, physical barriers, chemical barriers, isotopic barriers, and radiological barriers. This paper tests the categorization methods for nuclear materials from pyroprocessing which converts spent oxide fuels to metallic forms and separates transuranic elements from fission products. TRU ingots from pyroprocessing are classified into Category I by all methods. However, several inconsistencies of categorization methods were found. The attractiveness level of TRU ingots can be differently interpreted as two different levels for some methods. For some materials, the application of radiological barriers results in different categories. Some approaches adopt multiple levels of radiological barriers for different capabilities of terrorists. Many methods evaluate materials as the current forms without considering the difficulty of separation, but a few methods consider chemical separation. Some methods exempt U ingots, but the others do not. © 2017 Elsevier B.V.

Kim T.H.,Pohang University of Science and Technology | Kwon J.G.,Pohang University of Science and Technology | Yoon S.H.,Korea Institute of Nuclear Nonproliferation and Control | Park H.S.,Pohang University of Science and Technology | And 2 more authors.
Nuclear Engineering and Design | Year: 2015

One of the key issues of the PCHE technology in the supercritical CO2 Brayton cycle is to achieve an efficient and compact designs to be able to enhance heat transfer and reduce pressure drop. The issue is challenging due to the complex configuration of micro-channels in the PCHE. In this study, an innovative micro-channel equipped with an array of airfoil fins is analyzed to evaluate its performance. In so doing, sensitivity analysis with various design parameters is performed to configure the optimal arrangement of airfoil fins by using CFD analysis for Supercritical Carbon dioxide Integral Experimental Loop (SCIEL) in Korean Atomic Energy Research Institute (KAERI). Dominant geometric parameters of the fin arrangement that affects to the thermal and hydraulic performances are the horizontal, vertical and staggered pitches. ANSYS ICEM CFD and ANSYS CFX are used for the grid generation and the computational calculation. CO2 properties are used by using REFPROF software database. The inlet temperature of the hot side is 618 K and that of the cold side is 585 K. The reference mass flow rate is set as 1.2 g/s for the vertical number of 2.0, which is the Reynolds number of about 30,000. The mass flow rate changes from 0.4 to 4.8 g/s in order to investigate the Reynolds number effect. The k-ε model is selected as the turbulence model. In conclusions, the results show that the optimal arrangement of airfoil fins can be examined in terms of an objective function and it is obtained as the arrangement has the staggered number of 1.0. © 2015 Elsevier B.V. All rights reserved.

Yoo H.-S.,Korea Institute of Nuclear Nonproliferation and Control | Yoo H.-S.,Chungnam National University | Ryu H.-Y.,Chungnam National University | Cho S.-S.,Chungnam National University | And 3 more authors.
International Journal of Hydrogen Energy | Year: 2011

The effect of Si content in Al-Si alloy powder with NaOH on H2 production was investigated. The total amount of H2 produced decreased as Si content increased, which is inconsistent with the results predicted by the chemical reaction. Si caused a delay in the rate of H 2 production. Energy dispersive spectrometry showed that a large amount of unreacted Si remained in the matrix, and the unreacted fraction increased as the Si content increased. As the evolution reaction of Al and Al-Si alloys is exothermic, the temperature of all the specimens increased. Si addition reduced the hydroxide removal rate, which decreased the average H 2 production rate. The initiation time for H2 evolution depends on the elimination rate of the oxide film formed during production of the powder. On increasing the Si content, SiO2 was formed, which is harder to eliminate than Al2O3; this delayed the initiation. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Baek C.-H.,Dongseo University | An S.J.,Yonsei University | Kim H.-I.,Yonsei University | Kwak S.-W.,Korea Institute of Nuclear Nonproliferation and Control | Chung Y.H.,Yonsei University
Radiation Measurements | Year: 2013

The collimator design for a nuclear monitoring system should be considered differently from the collimator design for medical environments because it has to be used in high-energy radiation environments. The purpose of this study was to determine the optimum pinhole design and to evaluate its performance for acquiring good-quality image in a high-energy radiation field. Simulations using the Geant4 Application for Tomographic Emission (GATE) were performed to model the pinhole gamma camera system. The gamma camera consists of a pyramid-shaped lead collimator with a tungsten pinhole insert, and a CsI(Tl) scintillation crystal with thickness of 6.0 mm and area of 50.0 mm × 50.0 mm. The acceptance angle of the pinhole collimator and the distance from pinhole to scintillator crystal were set to 45 and 60 mm, respectively. The intrinsic spatial resolution and sensitivity were simulated by changing the pinhole diameter and channel height. The point source was located 60 mm above the center of the pinhole, and the transmitted image was estimated for pinhole diameter values from 2.0 mm to 4.0 mm, while the channel heights were fixed between 2.0 mm and 6.0 mm. The optimal ranges of channel height and pinhole diameter were determined by evaluating the intrinsic resolution and sensitivity tradeoff curves. The pinhole parameters were selected based on these analyses, and we verified the simulation results through experimental tests of three types of collimators (general purpose, high sensitivity, and high resolution). The simulated and experimental results agreed, with discrepancies of 4.5% and 6.4% in the sensitivity and spatial resolution, respectively. The results demonstrate that the pinhole collimator designed in this study could be utilized to perform radiation monitoring. © 2013 Elsevier Ltd. All rights reserved.

No Y.G.,Korea Atomic Energy Research Institute | Kim J.H.,Chosun University | Na M.G.,Chosun University | Lim D.H.,Korea Institute of Nuclear Nonproliferation and Control | Ahn K.-I.,Korea Atomic Energy Research Institute
Nuclear Engineering and Technology | Year: 2012

After the Fukushima nuclear accident in 2011, there has been increasing concern regarding severe accidents in nuclear facilities. Severe accident scenarios are difficult for operators to monitor and identify. Therefore, accurate prediction of a severe accident is important in order to manage it appropriately in the unfavorable conditions. In this study, artificial intelligence (AI) techniques, such as support vector classification (SVC), probabilistic neural network (PNN), group method of data handling (GMDH), and fuzzy neural network (FNN), were used to monitor the major transient scenarios of a severe accident caused by three different initiating events, the hot-leg loss of coolant accident (LOCA), the cold-leg LOCA, and the steam generator tube rupture in pressurized water reactors (PWRs). The SVC and PNN models were used for the event classification. The GMDH and FNN models were employed to accurately predict the important timing representing severe accident scenarios. In addition, in order to verify the proposed algorithm, data from a number of numerical simulations were required in order to train the AI techniques due to the shortage of real LOCA data. The data was acquired by performing simulations using the MAAP4 code. The prediction accuracy of the three types of initiating events was sufficiently high to predict severe accident scenarios. Therefore, the AI techniques can be applied successfully in the identification and monitoring of severe accident scenarios in real PWRs.

Ryu H.-W.,Korea University | Han J.-J.,Korea Institute of Nuclear Nonproliferation and Control | Kim Y.-J.,Korea University
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2015

This study provides the application of damage model to complex cracked pipes which can be found especially in weld overlay region. From the perspective of structural integrity, enough basic and large-scale tests are required to accurately evaluate the components containing a crack-like defect. In this case, damage model using finite element (FE) method can be effectively used for the assessment of full-scale cracked pipes with minimum basic experiments data. The proposed method in this research is based on the stress-modified fracture strain damage model with stress reduction technique. In this paper, Battelle full-scale complex cracked pipe tests are simulated by the proposed damage model with reasonable procedure. FE simulation is conducted for basic experiments to determine failure criteria with calibrations. Then, crack initiation and maximum loads are predicted to characterize the fracture behavior of full-scale complex cracked pipes. Damage model is applied to both of carbon and stainless steel materials and verification with comparing to test data is conducted. Copyright © 2015 by ASME.

Kim H.-I.,Yonsei University | Baek C.-H.,Yonsei University | Jung An S.,Yonsei University | Kwak S.-W.,Korea Institute of Nuclear Nonproliferation and Control | Hyun Chung Y.,Yonsei University
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2013

The purpose of this study was to develop and evaluate a gamma camera with a newly designed diverging collimator for monitoring radiation fields in nuclear medicine. Simulations using the Geant4 Application for Tomographic Emission (GATE) were performed to model the gamma camera system designed to monitor Tc-99m radioactive isotopes usually used in nuclear medicine. A gamma camera consists of a diverging collimator, a CsI(Na) scintillation crystal with dimensions of 50.0 mm×50.0 mm×6.0 mm and Hamamatsu H8500 PSPMT. The diverging collimator is composed of two layers of diverging slats stacked directly above each other, and the front layer is rotated by 90° with respect to the back layer. The point source at different positions was simulated, and the optimal slat thickness and slat height were determined by evaluating the spatial resolution and sensitivity. The slat thickness is 1.0 mm, the slat height is 40.0 mm and the angle of slats ranges from 0 to 22.5 °. The front and back layers are composed of 40 and 18 slats, respectively, to achieve equal spatial resolution in the x and y directions. The diverging collimator improves the uniformity of the spatial resolution and sensitivity across the field of view and the count rate better than the pinhole collimator. Experimental measurements were performed, and the results agreed well with simulations in terms of spatial resolution and sensitivity. The results demonstrated that the two-layer diverging-slat collimator is suitable for large area monitoring of the radiation fields. © 2012 Elsevier B.V.

Park S.,Korea Institute of Nuclear Nonproliferation and Control | Kwak S.-W.,Korea Institute of Nuclear Nonproliferation and Control | Shin J.-K.,Korea Institute of Nuclear Nonproliferation and Control
2015 4th International Conference on Advancements in Nuclear Instrumentation Measurement Methods and their Applications, ANIMMA 2015 | Year: 2015

An integrated system of X-ray Absorption Spectrometry (XAS), also called L-edge densitometry for uranium (LED) and X-ray Fluorescence spectrometry (XRF) is designed using Monte Carlo simulation for determining concentration of uranium and minor actinides for safeguards. The equipment is compact compared to the K-edge densitometer with high purity germanium detector with liquid nitrogen cooling due to using a low energy X-ray source and a heavy shielding system. The system has been validated from simulation and analysis of the LED/XRF spectrum from this feasibility study. © 2015 IEEE.

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