• Nuclear Engineering and Technology
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• v.44 no.6
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• pp.561-586
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• 2012

This paper describes a summary of final prediction results by system-scale safety analysis codes during the OECD/NEA/CSNI ISP-50 exercise, targeting a 50% Direct Vessel Injection (DVI) line break integral effect test performed with the Advanced Thermal-Hydraulic Test Loop for Accident Simulation (ATLAS). This ISP-50 exercise has been performed in two consecutive phases: "blind" and "open" phases. Quantitative comparisons were performed using the Fast Fourier Transform Based Method (FFTBM) to compare the overall accuracy of the collected calculations. Great user effects resulting from the combination of the possible reasons were found in the blind phase, confirming that user effect is still one of the major issues in connection with the system thermal-hydraulic code application. Open calculations showed better prediction accuracy than the blind calculations in terms of average amplitude (AA) value. A total of nineteen organizations from eleven countries participated in this ISP-50 program and eight leading thermal-hydraulic system analysis codes were used: APROS, ATHLET, CATHARE, KORSAR, MARS-KS, RELAP5/MOD3.3, TECH-M-97, and TRACE.

• The Journal of Korean Medicine
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• v.19 no.1
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• pp.339-348
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• 1998

We can have the following summary regarding the apple, what is called, 'the king of fruits' through the study of bibliographic science. 1. Im-keum(林檎) could be translated into 'Neung-keum'(능금)(Malus asiatiaz Nakai), Nea(奈) into 'Meut'(멋), and Bin-gwa into 'apple'(사과)(Malus pumila Mill), and Bin-gwa was reformed from Meut. Thus, Neung-keum is similar to the apple, yet it is' different each other. 2. The imported year of the apple which was reformed from Meut(멋) from China was in 1654 whereas Neung-keum(능금) is a native kind. 3. The apple inscribed by Sa-gwa(沙果) on the present korean language dictionary should be changed into Sa-gwa. The Sa-gwa(沙果) is used as another name of Neug-keum(능금) in China. 4. We can find the bibliographic record that an apple or Neug-keum(능금) had been used as a substitution of San-sa(山사) to be used to Soe-um-in(小陰人). 5. The apple and Neug-keum(능금) are recommended to the Soe-um-in(少陰人) as a food for Yang-ran-ji-gi(陽煖之氣) to be served as Bo-myung-ji-ji(保險之主) to Soe-um-in(少陰人).

• Nuclear Engineering and Technology
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• v.41 no.6
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• pp.753-764
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• 2009

JAEA started the LSTF experiments in 1985 for the fourth stage of the ROSA Program (ROSA-IV) for the LWR thermal-hydraulic safety research to identify and investigate the thermal-hydraulic phenomena and to confirm the effectiveness of ECCS during small-break LOCAs and operational transients. The LSTF experiments are underway for the ROSA-V Program and the OECD/NEA ROSA Project that intends to resolve issues in thermal-hydraulic analyses relevant to LWR safety. Six types of the LSTF experiments have been done for both the system integral and separate-effect experiments among international members from 14 countries. Results of four experiments for the ROSA Project are briefly presented with analysis by a best-estimate (BE) code and a computational fluid dynamics (CFD) code to illustrate the capability of the LSTF and codes to simulate the thermal-hydraulic phenomena that may appear during SBLOCAs and transients. The thermal-hydraulic phenomena dealt with are coolant mixing and temperature stratification, water hammer up to high system pressure, natural circulation under high core power condition, and non-condensable gas effect during asymmetric SG depressurization as an AM action.

• Nuclear Engineering and Technology
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• v.50 no.2
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• pp.280-291
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• 2018

In the framework of OECD/NEA Working Group on Fuel Safety, a RIA fuel-rod-code Benchmark Phase I was organized in 2010-2013. It consisted of four experiments on highly irradiated fuel rodlets tested under different experimental conditions. This benchmark revealed the need to better understand the basic models incorporated in each code for realistic simulation of the complicated integral RIA tests with high burnup fuel rods. A second phase of the benchmark (Phase II) was thus launched early in 2014, which has been organized in two complementary activities: (1) comparison of the results of different simulations on simplified cases in order to provide additional bases for understanding the differences in modelling of the concerned phenomena; (2) assessment of the uncertainty of the results. The present paper provides a summary and conclusions of the second activity of the Benchmark Phase II, which is based on the input uncertainty propagation methodology. The main conclusion is that uncertainties cannot fully explain the difference between the code predictions. Finally, based on the RIA benchmark Phase-I and Phase-II conclusions, some recommendations are made.

• Nuclear Engineering and Technology
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• v.50 no.6
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• pp.829-841
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• 2018

An experiment was conducted for the OECD/NEA ROSA-2 Project using the large-scale test facility (LSTF), which simulated a 17% hot leg intermediate-break loss-of-coolant accident in a pressurized water reactor (PWR). In the LSTF test, core uncovery started simultaneously with liquid level drop in crossover leg downflow-side before loop seal clearing, and water remaining occurred on the upper core plate in the upper plenum. Results of the uncertainty analysis with RELAP5/MOD3.3 code clarified the influences of the combination of multiple uncertain parameters on peak cladding temperature within the defined uncertain ranges. For studying the scaling problems to extrapolate thermal-hydraulic phenomena observed in scaled-down facilities, an experiment was performed for the OECD/NEA PKL-3 Project with the Primarkreislaufe Versuchsanlage (PKL), as a counterpart to a previous LSTF test. The LSTF test simulated a PWR 1% hot leg small-break loss-of-coolant accident with steam generator secondary-side depressurization as an accident management measure and nitrogen gas inflow. Some discrepancies appeared between the LSTF and PKL test results for the primary pressure, the core collapsed liquid level, and the cladding surface temperature probably due to effects of differences between the LSTF and the PKL in configuration, geometry, and volumetric size.

• Publications of The Korean Astronomical Society
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• v.38 no.2
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• pp.25-36
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• 2023

Since interstellar objects like 1I/'Oumuamua and 2I/Borisov originate from exoplanetary systems, even if we do not visit the exoplanetary systems, flyby, rendezvous, and sample return missions of interstellar objects can provide clues to solve the mysteries of cosmic life phenomena such as the origin of exoplanetary systems, galactic evolution, biosignatures (or even technosignatures), and panspermia. In this paper, we review space missions for interstellar object exploration in the stage of mission design or concept study such as Project Lyra, Bridge, Comet Interceptors, and Lightcraft^TM. We also review space missions, OSIRIS-REx and NEA Scout, designed for Near Earth Asteroids(NEA) explorations, to investigate the current state of basic technologies that can be extended to explore interstellar objects in a velocity of ~ 6AU/year. One of the technologies that needs to be developed for interstellar object exploration is a spacecraft propulsion method such as solar sail, which can catch up with the fast speed of interstellar objects. If this kind of propulsion becomes practical for space explorations, interstellar object explorations will mark a new era and serve as a driving force to provide evidences of cosmic life.

• Nuclear Engineering and Technology
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• v.56 no.9
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• pp.3654-3667
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• 2024

Expanding upon the framework of the steady-state pin-by-pin 2D/1D decoupling method, a novel and highperformance pin-by-pin transient calculation method has been introduced. This transient method, consistent to the steady-state formulation, is designed for time-dependent calculations utilizing a 3D diffusion-based finite difference method (FDM). The inherent complexity of the large 3D problem is effectively managed by decoupling it into a series of planar (2D) and axial (1D) problems. In addition, tens of thousands of pin-cells are grouped into hundreds of boxes to reduce the computing burden for the 1D calculations without essential loss of the accuracy. Two-level coarse mesh finite difference (CMFD) formulation comprising multigroup nodewise CMFD and twogroup assemblywise CMFD is employed as well to accelerate the convergence. Errors originating from the pinlevel homogenization, energy group condensation, and the use of lower order calculation methods are simultaneously corrected by the pinwise super homogenization (SPH) equivalence factor. The transient method is evaluated with OECD/NEA PWR MOX/UO2 benchmark. Code-to-code comparison with the nTRACER direct whole core calculation code yielded highly satisfactory results for the transient scenario as well as the steady-state problems. Furthermore, comparative analyses with conventional nodal calculations show superiority of the pin-by-pin calculation.

• Nuclear Engineering and Technology
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• v.44 no.2
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• pp.151-160
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• 2012

The advantages for using Monte Carlo methods to analyze full-core reactor configurations include essentially exact representation of geometry and physical phenomena that are important for reactor analysis. But this substantial advantage comes at a substantial cost because of the computational burden, both in terms of memory demand and computational time. This paper focuses on the challenges facing full-core Monte Carlo for keff calculations and the prospects for Monte Carlo becoming a routine tool for reactor analysis.

• Nuclear industry
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• v.18 no.9 s.187
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• pp.66-77
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• 1998

온실 가스 배출로 인하여 지구 온난화 문제가 심각성을 더해가고 있는 차제에 지난해(1997) 12월 일본 교토에서 제3차 기후변화협약 조약국 회의가 개최되었으며, 회의 결과 일차적으로 선진국에서 온실 가스 배출 감축 목표를 설정하여 2008년부터 시행토록 합의하였다. 우리 나라는 이 회의에서 온실 가스 배출 감축 대상국에서는 제외되었지만 OECD에 가입한 국가로서 멀지 않아 감축 목표 이행 대상국에 들게 될 것으로 예측된다. 이와 관련하여 OECD/NEA는 지난 4월 $\ulcorner$원자력발전과 기후변화$\lrcorner$라는 보고서를 발표하였다. 이 보고서는 비교적 최근의 연구 자료를 인용하여 원자력이 온실 가스 배출 억제에 어떤 역할을 하는가를 연구한 내용으로서 우리 나라에서도 에너지 정책 입안 등에 도움이 될 것으로 판단된다.

• Nuclear industry
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• v.37 no.4
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• pp.72-83
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• 2017

'미래 세대를 위한 우리의 에너지 선택'을 주제로 한 국내외 원자력 에너지 전문가 좌딤회가 4월 5일 경주 힐튼호텔 오크룸에서 열렸다. 원자력산업회의와 원자력문화재단이 공동 주최한 이번 좌담회는 4월 5~6일 열린 '2017 한국원자력연차대회'에 참석한 해외 원자력 전문가를 초청하여 마련된 것으로, 강재열 한국원자력산업회의 상근부회장(좌장), 김호성 한국원자력문화재단 이사장, William D. Magwood IV OECD-NEA 사무총장, Gordon Mackerron 영국 Sussex 대학교 과학정책연구소(SPRU) 교수, Tomoko Murakami 일본에너지경제연구소(IEEJ) 연구책임자, Michael Shellenberger 미국 Environmental Progress 회장 등이 참석하여 2시간에 걸쳐 의견을 나누었다. 좌담회 전문을 게재한다.