• Nuclear Engineering and Technology
• /
• 제48권5호
• /
• pp.1109-1119
• /
• 2016

Although, the direct use of spent pressurized water reactor (PWR) fuel in CANda Deuterium Uranium (CANDU) reactors (DUPIC) cycle is still under investigation, DUPIC cycle is a promising method for uranium utilization improvement, for reduction of high level nuclear waste, and for high degree of proliferation resistance. This paper focuses on the effect of DUPIC cycle on CANDU reactor safety parameters. MCNP6 was used for lattice cell simulation of a typical 3,411 MWth PWR fueled by $UO_2$ enriched to 4.5w/o U-235 to calculate the spent fuel inventories after a burnup of 51.7 MWd/kgU. The code was also used to simulate the lattice cell of CANDU-6 reactor fueled with spent fuel after its fabrication into the standard 37-element fuel bundle. It is assumed a 5-year cooling time between the spent fuel discharges from the PWR to the loading into the CANDU-6. The simulation was carried out to calculate the burnup and the effect of DUPIC fuel on: (1) the power distribution amongst the fuel elements of the bundle; (2) the coolant void reactivity; and (3) the reactor point-kinetics parameters.

• 대한공간정보학회지
• /
• 제10권5호
• /
• pp.53-65
• /
• 2002

The most widespread techniques for DEM generation are stereoscopy for optical sensor images and SAR interferometry(InSAR) for SAR images. These techniques suffer from certain sensor and processing limitations, which can be overcome by the synergetic use of both sensors and DEMs respectively. This study is associated with improvements of accuracy with consistency of image's characteristics between two different DEMs coming from stereoscopy for the optical images and interferometry for SAR images. The MWD(Multiresolution Wavelet Decomposition) and HPF(High-Pass Filtering), which take advantage of the complementary properties of SAR and stereo optical DEMs, will be applied for the fusion process. DEM fusion is tested with two sets of SPOT and ERS-l/-2 satellite imagery and for the analysis of results, DEM generated from digital topographic map(1 to 5000) is used. As a result of an integration of DEMs, it can more clearly portray topographic slopes and tilts when applying the strengths of DEM of SAR image to DEM of an optical satellite image and in the case of HPF, the resulting DEM.

• Corrosion Science and Technology
• /
• 제18권5호
• /
• pp.175-181
• /
• 2019

A failed spent fuel rod with 53,000 MWd/tU from a nuclear power plant was characterized, and the fission products and oxygen layer in the pellet-clad mechanical interaction region were observed using an EPMA (Electron Probe Micro-Analyzer). A sound fuel rod burned under similar conditions was used to compare and analyze, the results of the failed fuel rod. In the failed fuel rod, the oxide layer represented $10{\mu}m$ of the boundary of the cladding, and $35{\mu}m$ of the region outside the cladding. By comparison, in the sound fuel rod, the oxide layer was $8{\mu}m$, observed in the cladding boundary region. The cladding inner surface corrosion and the resulting fuel-cladding bonding were investigated using an EPMA. Zirconium existed in the bonding layer of the (U, Zr)O compound beyond the pellet cladding interaction gap of $20{\mu}m$, and composition of UZr2O3 was observed in the failed fuel rod. This paper presents the results of the EPMA examination of a spent fuel specimen, and a technique to analyze fission products in the pellet-clad mechanical interaction region.

• Nuclear Engineering and Technology
• /
• 제53권9호
• /
• pp.2830-2838
• /
• 2021

This work deals with the assessment of the burnup capabilities of the Serpent Monte Carlo code to predict spent nuclear fuel (SNF) isotopic concentrations for low-enriched uranium (LEU) fuel at different burnup levels up to 47 MWd/kgU. The irradiation of six UO₂ experimental samples in three different VVER-1000 reactor units has been simulated and the predicted concentrations of actinides up to ²⁴⁴Cm have been compared with the corresponding measured values. The results show a global good agreement between calculated and experimental concentrations, in several cases within the margins of the nuclear data uncertainties and in a few cases even within the reported experimental uncertainties. The differences in the performances of the JEFF3.1.1, ENDF/B-VII.1 and ENDF/B-VIII.0 nuclear data libraries (NDLs) have also been assessed and the use of the newly released ENDF/B-VIII.0 library has shown an increased accuracy in the prediction of the C/E's for some of the actinides considered, particularly for the plutonium isotopes. This work represents a step forward towards the validation of advanced simulation tools against post irradiation experimental data and the obtained results provide an evidence of the capabilities of the Serpent Monte-Carlo code with the associated modern NDLs to accurately compute SNF nuclide inventory concentrations for VVER-1000 type reactors.

• Nuclear Engineering and Technology
• /
• 제51권2호
• /
• pp.377-383
• /
• 2019

Targeting at simulating the application of thorium-uranium (TU) fuel in the CANDU-6 reactor, this paper analyzes the process using the code DRAGON/DONJON where the discrete TU fuel pins are applied in the CANDU-6 reactor under the time-average equilibrium refueling. The results show that the coolant void reactivity of the assembly analyzed in this paper is lower than that of 37-element bundle cell with natural uranium and 37-element bundle cell with mixed TU fuel pins; that the max time-average channel/bundle power of the core meets the limits - less than 6700kW/860 kW; that the fuel conversion ratio is higher than that of the CANDU-6 reactor with natural uranium; and that the exit burnup increases to 13400 MWd/tU. Thus, the simulation in this paper with the fuel in the 37-element bundle cell using discrete TU fuel pins can be considered to be applied in CANDU-6 reactor with adequate modifications of the core structure and operating modes.

• 대한한의학회지
• /
• 제44권4호
• /
• pp.193-207
• /
• 2023

Objectives: The purpose of this study was to evaluate the effectiveness and safety of traditional herbal medicine as a stand-alone treatment group through major English databases due to the lack of RCTs in Korea, and to provide a review of the herbal interventions used. Methods: Using four databases (Pubmed, EMBASE, OASIS, RISS), combination of words such as "Coronavirus" "RCT" "Herb" "Decoction" "TCM" were used. RCTs using herbal medicines to treat coronavirus were searched. Final 4 studies were selected by two authors according to inclusion and exclusion criteria. Results: A total of 1,435 patients were studied. The Chinese herbs used in the treatment group were Shengmai Yin, JingYinGuBiao granules, Jinhua Qinggan granules, and Bufei Huoxue capsules. The intervention group showed greater attenuation of pneumonia lesions on CT. Also, improvement in 6-min walk distance (6MWD), and negative conversion rate in treatment group were reported. Furthermore, scores on the Fatigue Assessment Inventory (FAI) were lower in the herbal group than in the placebo group. The median time to recovery of COVID-19 related symptoms was shorter in TCM group compared to the control group. Reported adverse effects were diarrhea, liver dysfunction, and excessive menstruation, and two papers did not mention side effects in detail. Conclusion: Herbal medicine alone can increase the conversion rate of viral negativity and relieve COVID-19 related symptoms without significant adverse effects.

• Tuberculosis and Respiratory Diseases
• /
• 제64권6호
• /
• pp.433-438
• /
• 2008

연구배경: COPD 환자에서 최대산소섭취량의 측정은 호흡재활치료에서 운동 강도의 결정과 치료 반응을 평가 하는데 사용된다. 하지만 운동부하 심폐기능 검사는 공간및 비용 등의 문제로 우리나라에서는 보편화되어 있지 않다. 한편 6분 보행검사는 간단하게 운동능력을 평가할 수 있는 방법으로 신뢰도가 높고 운동능력의 변화를 비교적잘 반영한다. 본 연구에서는 중등도 이상의 COPD 환자에서 $6M_{work}$을 이용해 최대산소섭취량을 예측하는 공식을 구하고자 하였다. 방 법: 중등도 이상의 COPD 남성 33명을 대상으로 전향적 다기관 연구를 진행하였다. 최초 방문시 폐기능검사, 운동부하 심폐기능 검사와 6분 보행검사를 실시하였고, 보행거리와 체중을 곱하여 $6M_{work}$을 구한 다음 최대산소섭취량과 상관관계가 높은 변수들을 찾아 다중회귀분석법을 이용하여 추정 예측식을 구하였다. 결 과: 환자의 평균 연령은 67.7세, 신체질량지수는 $22.5kg/m^2$였다. $FEV_1$의 평균값은 1.33 L (정상 예측치의 51.1%)이었고, 최대산소섭취량도 1,015.9 ml/min (정상 예측치의 50.8%)로 낮게 측정되었다. 평균 6분 보행거리는 516 m, $6M_{work}$는 32,811이었으며, $6M_{work}$가 6분 보행거리보다 최대산소섭취량과 더 높은 상관관계를 보였다. 또한 $FEV_1$, 폐확산능, FVC가 최대산소섭취량과 높은 상관관계를 보였다. 다중회귀분석으로 얻어진 예측식은 [최대산소섭취량(ml/min)=($274.306{\times}FEV_1$)+($36.242{\times}DLco$)+($0.007{\times}6M_{work}$)-84.867]이었다. 결 론: 최대산소섭취량 검사가 불가능한 상황에서의 대안으로 시행이 간편한 6분 보행검사를 보조적으로 이용할 수 있을 것으로 사료되며, 본 연구에서 얻어진 추정공식의 타당성에 대한 대규모 연구가 필요하다.

• 한국토양비료학회지
• /
• 제42권3호
• /
• pp.201-206
• /
• 2009

신선유기물 (이탈리안 라이그라스), 신선유기물 + 부산물비료 그리고 부산물비료 처리 후 3년 동안 토양입단 발달상태를 조사한 결과, 토양별로는 모래 함량이 상대적으로 높은 새만금 간척지 토양 보다는 미사와 점토함량이 높은 고흥 간척지 토양에서의 입단형성이 더 양호한 것으로 나타났다. 유기물 자원 처리별로는 고흥 간척지 토양에서는 유의성 있는 차이가 나타나지 않았으나 (P<0.05), 새만금 간척지 토양에서는 녹비 형태의 신선 유기물 즉, 이탈리안 라이그라스를 처리한 시험구에서 가장 입단화도가 높게 나타났다. 유기물 종류별로는 이탈리안 라이그라스와 같은 신선 유기물을 단독 처리한 시험구에서 토양 입단의 중량평균직경이 가장 크게 나타났다. 간척지 토양의 물리성 및 토양구조 개선을 위한 유기물 처리시 신선유기물의 처리가 바람직하며, 불가피할 경우 일반 유기질/부산물비료의 단독처리보다는 신선유기물과 혼합하여 처리하는 것이 타당한 것으로 조사되었다.

• Nuclear Engineering and Technology
• /
• 제52권2호
• /
• pp.248-257
• /
• 2020

This study presents an initial design for a novel system consisting in a coupled nuclear reactor and a phase change material-based thermal energy storage (TES) component, which acts as a buffer and regulator of heat transfer between the primary and secondary loops. The goal of this concept is to enhance the capacity factor of nuclear power plants (NPPs) in the case of high integration of renewable energy sources into the electric grid. Hence, this system could support in elevating the economics of NPPs in current competitive markets, especially with subsidized solar and wind energy sources, and relatively low oil and gas prices. Furthermore, utilizing a prismatic-core advanced high temperature reactor (PAHTR) cooled by a molten salt with a high melting point, have the potential in increasing the system efficiency due to its high operating temperature, and providing the baseline requirements for coupling other process heat applications. The present research studies the neutronics and thermal hydraulics (TH) of the PAHTR as well as TH calculations for the TES which consists of 300 blocks with a total heat storage capacity of 150 MWd. SERPENT Monte Carlo and MCNP5 codes carried out the neutronics analysis of the PAHTR which is sized to have a 5-year refueling cycle and rated power of 300 MW_th. The PAHTR has 10 metric tons of heavy metal with 19.75 wt% enriched UO₂ TRISO fuel, a hot clean excess reactivity and shutdown margin of $33.70 and -$115.68; respectively, negative temperature feedback coefficients, and an axial flux peaking factor of 1.68. Star-CCM + code predicted the correct convective heat transfer coefficient variations for both the reactor and the storage. TH analysis results show that the flow in the primary loop (in the reactor and TES) remains in the developing mixed convection regime while it reaches a fully developed flow in the secondary loop.

• 폴리머
• /
• 제27권5호
• /
• pp.502-507
• /
• 2003

메탈로센 선형 저밀도 폴리에틸렌 (m-LLDPE)과 저밀도 폴리에틸렌 (LDPE)을 용응 블렌딩 방법으로 블렌드를 제조하여 열적 거동 및 물성을 관찰하였다. LDPE/m-LLDPE1 블렌드는 LDPE조성이 50% 이상이면 두 개의 용융 피크가 관찰된 반면 다른 블렌드들은 단일한 용융 피크를 나타내었다. m-LLDPE에서 공단량체 함량이 감소할수록 용융 온도와 상대 결정화도가 증가하였다. 공단량체 함량이 2 wt%인 m-LLDPE1이 초기 탄성률이 가장 높게 관찰되었고, 공단량체 함량이 증가함에 따라 감소하였다. 블렌드에서 조성에 따른 초기 탄성률의 변화는 상대 결정화도의 거동과 유사하게 나타났다. 블렌드의 파괴 신율은 LDPE/m-LLDPE1과 LDPE/m-LLDPE2 블렌드에서 평균값보다 낮은 파괴 신율을 나타내었었다. m-LLDPE2의 용융 지수가 가장 높게 관찰되었고 공단량체 함량이 증가함에 따라 감소하는 경향을 나타내었다.