• Nuclear Engineering and Technology
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• 제7권2호
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• pp.159-165
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• 1975

The Nuclear power industry today faces a serious and rapidly emerging problem in reactor maintenance and occupational radiation exposure control. The basic problem is the need for much maintenance on nuclear power plants. The problem is seriously compounded by radiation exposure control requirements. Many studies are underway seeking solutions tut the industry is developing rapidly and new plants will not await the results of such studies. It is essential that attention be given to maintenance and exposure control in all phases of plant design, construction and operation.

• 융합보안논문지
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• 제15권6_1호
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• pp.33-42
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• 2015

2015년 7월 이란과 서방국가와의 잠재적인 핵협상이 극적으로 체결됨에 따라 오랜 기간 동안 문제되었던 이란의 핵 문제가 서서히 해결되고 있다. 이란의 핵협상 과정을 눈여겨 봐야 하는 이유는 한반도 역시 북한의 핵문제로 인해 큰 위협을 받고 있기 때문이다. 북한과 이란의 핵문제를 비교할 경우 양 국의 정치체계와 구조, 핵협상 과정에서 큰 차이가 있기 때문에 북한의 핵문제를 해결하기 위한 정책적 시사점을 찾기가 사실상 어렵다. 일부에서는 이란의 핵문제와 북한의 핵문제와는 상당한 차이가 있기 때문에 이란의 핵협상으로부터 북한의 핵문제 해결을 위한 시사점을 찾기 힘들 것이라는 부정적 견해를 내고 있고 또 다른 한편에서는 이란의 핵협상 결과가 분명 북한의 핵문제에 긍정적 영향을 미칠 수 있는 요인을 찾을 수 있을 것이라는 견해를 제시하고 있다. 이란과 북한의 핵문제가 상당한 차이가 있음에도 불구하고 이란의 핵 협상과정에서 북핵문제 해결을 위한 긍정적인 방안을 찾고자 하는 것은 그만큼 북한의 핵문제가 한반도 전체의 사활과 관련된 문제이기 때문이다. 본 연구에서는 이란의 핵협상 타결과정과 성공요인을 분석하는 데 초점을 맞추고, 분석된 요인으로부터 북한의 핵문제 해결을 위한 시사점을 알아보고자 한다.

• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1350-1364
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• 2023

2D/1D coupling method is an important neutron transport calculation method due to its high accuracy and relatively low computation cost. However, 2D/1D coupling method may diverge especially in small axial mesh size. To analyze the convergence behavior of 2D/1D coupling method, a Fourier analysis for k-eigenvalue neutron transport problems is implemented. The analysis results present the divergence problem of 2D/1D coupling method in small axial mesh size. Several common attempts are made to solve the divergence problem, which are to increase the number of inner iterations of the 2D or 1D calculation, and two times 1D calculations per outer iteration. However, these attempts only could improve the convergence rate but cannot deal with the divergence problem of 2D/1D coupling method thoroughly. Moreover, the choice of axial solvers, such as DGFEM SN and traditional SN, and its effect on the convergence behavior are also discussed. The results show that the choice of axial solver is a key point for the convergence of 2D/1D method. The DGFEM SN based 2D/1D method could converge within a wide range of optical thickness region, which is superior to that of traditional SN method.

• Nuclear Engineering and Technology
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• 제51권4호
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• pp.968-976
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• 2019

This paper presents a number of verification case studies for a recently developed sensitivity/uncertainty code package. The code package, ROMUSE (Reduced Order Modeling based Uncertainty/Sensitivity Estimator) is an effort to provide an analysis tool to be used in conjunction with reactor core simulators, in particular the Virtual Environment for Reactor Applications (VERA) core simulator. ROMUSE has been written in C++ and is currently capable of performing various types of parameter perturbations and associated sensitivity analysis, uncertainty quantification, surrogate model construction and subspace analysis. The current version 2.0 has the capability to interface with the Design Analysis Kit for Optimization and Terascale Applications (DAKOTA) code, which gives ROMUSE access to the various algorithms implemented within DAKOTA, most importantly model calibration. The verification study is performed via two basic problems and two reactor physics models. The first problem is used to verify the ROMUSE single physics gradient-based range finding algorithm capability using an abstract quadratic model. The second problem is the Brusselator problem, which is a coupled problem representative of multi-physics problems. This problem is used to test the capability of constructing surrogates via ROMUSE-DAKOTA. Finally, light water reactor pin cell and sodium-cooled fast reactor fuel assembly problems are simulated via SCALE 6.1 to test ROMUSE capability for uncertainty quantification and sensitivity analysis purposes.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 추계학술발표회
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• pp.578-579
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• 2005

• 전기의세계
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• 제27권6호
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• pp.58-62
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• 1978

The problem of optimal shutdown control of nuclear reactor having nonlinear dynamics is considered. Since the problem, being a bounded state space problem, is difficult to solve by conventional analytic methods such as Pontryagin's maximum principle, it is approached directly by the quasilinearization technique, and solved numerically. The solution obtained in this manner proves to be an improvement over the previous results.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 추계학술발표회논문집(1)
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• pp.21-26
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• 1996

The identification of radioactive source in a medium with a limited number of external detectors is introduced as an inverse radiation transport problem. This kind of inverse problem is usually ill-posed and severely under-determined, however, its applications are very useful in manu fields including medical diagnosis and nondestructive assay of nuclear materials. Therefore, it is desired to develop efficient and robust solution algorithms. As an approach to solving inverse problems, an artificial neural network is proposed. We develop a modified version of the conventional Hopfield neural network and demonstrate its efficiency and robustness.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.520-525
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• 2024

The optimization design problem of nuclear reactor radiation shield is a typical multi-objective optimization problem with almost 10 sub-objectives and the sub-objectives are always demanded to be under tolerable limits. In this paper, a design method combining multi-objective optimization algorithms with paralleling discrete ordinate transportation code is developed and applied to shield design of the Savannah nuclear reactor. Three approaches are studied for light-weighted and compact design of radiation shield. Comparing with directly optimization with 10 objectives and the single-objective optimization, the approach by setting sub-objectives representing weight and volume as optimization objectives while treating other sub-objectives as constraints has the best performance, which is more suitable to reactor shield design.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2001년도 춘계학술발표회요약집
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• pp.122-122
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• 2001

• Nuclear Engineering and Technology
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• 제28권3호
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• pp.311-319
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• 1996

We reconstruct the assembly pinwise flux using several types of boundary conditions and confirm that the reconstructed fluxes are the same with the reference flux if the boundary condition is exact. We test EPRI-9R benchmark problem with four boundary conditions, such as Dirichlet boundary condition, Neumann boundary condition, homogeneous mixed boundary condition (albedo type), and inhomogeneous mixed boundary condition. We also test reconstruction of the pinwise flux from nodal values, specifically from the AFEN [1, 2] results. From the nodal flux distribution we obtain surface flux and surface current distributions, which can be used to construct various types of boundary conditions. The result show that the Neumann boundary condition cannot be used for iterative schemes because of its ill-conditioning problem and that the other three boundary conditions give similar accuracy. The Dirichlet boundary condition requires the shortest computing time. The inhomogeneous mixed boundary condition requires only slightly longer computing time than the Dirichlet boundary condition, so that it could also be an alternative. In contrast to the fixed-source type problem resulting from the Dirichlet, Neumann, inhomogeneous mixed boundary conditions, the homogeneous mixed boundary condition constitutes an eigenvalue problem and requires longest computing time among the three (Dirichlet, inhomogeneous mixed, homogeneous mixed) boundary condition problems.