• 한국초전도ㆍ저온공학회논문지
• /
• 제4권1호
• /
• pp.99-104
• /
• 2002

This study deals with the optimal design of a DC reactor type high-Tc superconducting fault current limiter(SFCL). The condition in which the cost function is minimized under given constraints is one of the things to be first considered in developing SFCLS. This condition is a group of the values corresponding to the variables the cost function depends on. In this paper, the length of tape was taken as a dependent variable, the inductance of DC reactor and the turns ratio of magnetic core reactors as independent variables. For the SFCL available at the level of 6.6kV-200A, we examined 4 cases; at the fault times of 80msec, 50msec, 30msec and 10msec. Since thyristors would be utilized instead of diodes, we chose the result at 10msec as the basic data. Considering safety factor 30%, our optimal design was decided to be the inductance 570mH, the critical current over 620A, the turns ratio 0.89 and the fault time within 20msec.

• 한국표면공학회지
• /
• 제47권6호
• /
• pp.354-361
• /
• 2014

In order to utilize silicon carbide (SiC) as an inner part of fluidized bed reactor (FBR) for manufacturing poly-silicon, we have carried out the thermodynamic calculation on the overall reactions including poly-silicon synthesis and compatibility of SiC with FBR process. The resources of silicon included $SiH_4(MS)$, $SiHCl_3(TCS)$ and $SiCl_4(STC)$ and the thermodynamic yield of the FBR with MS, TCS and STC were compared each other with variable range of temperature, pressure and hydrogen to silicon ratio. The silicon yield of MS, TCS and STC were 100%, 28% and 4%, respectively, throughout the conventional FBR conditions. Silicon carbide having high hardness and strength showed strong resistance to granule collisions during the FBR process using a lab-scale reactor. And it also showed quite good compatibility with the typical FBR processes of MS and TCS resources.

• Nuclear Engineering and Technology
• /
• 제55권7호
• /
• pp.2395-2406
• /
• 2023

To study the influence of parameter uncertainty in small pressurized water reactor (SPWR) once-through steam generator (OTSG), the nonlinear mathematical model of the SPWR is firstly established. Including the reactor core model, the OTSG model and the pressurizer model. Secondly, a control strategy that both the reactor core coolant average temperature and the secondary-side outlet pressure of the OTSG are constant is adopted. Then, the uncertainty quantification method is established based on Latin hypercube sampling and statistical method. On this basis, the quantitative platform for parameter uncertainty of the OTSG is developed. Finally, taking the uncertainty in primary-side flowrate of the OTSG as an example, the platform application work is carried out under the variable load in SPWR and step disturbance of secondary-side flowrate of the OTSG. The results show that the maximum uncertainty in the critical output parameters is acceptable for SPWR.

• 품질경영학회지
• /
• 제37권2호
• /
• pp.46-57
• /
• 2009

The traditional approach to economic design of control charts is based on the assumption that a process is monitored using a performance variable. However, various types of automatic test equipments recently introduced as a part of factory automation usually measure surrogate variables instead of performance variables that are costly to measure. In this article we propose a model for economic design of a control chart which uses a surrogate variable that is highly correlated with the performance variable. The optimum values of the design parameters are determined by maximizing the total average income per cycle time. Numerical studies are performed to compare the proposed $\bar{X}$ control charts with the traditional model using the examples in Panagos et al. (1985).

• Nuclear Engineering and Technology
• /
• 제56권3호
• /
• pp.933-940
• /
• 2024

A macroscopic cross section generation model was developed for the conceptual horizontal, compact high temperature gas reactor (HC-HTGR). Because there are many sources of spectral effects in the design and analysis of the core, conventional LWR methods have limitations for accurate simulation of the HC-HTGR using a neutron diffusion core neutronics simulator. Several super-cell model configurations were investigated to consider the spectral effect of neighboring cells. A new history variable was introduced for the existing library format to more accurately account for the history effect from neighboring nodes and reactivity control drums. The macroscopic cross section library was validated through comparison with cross sections generated using full core Monte Carlo models and single cell cross section for both 3D core steady-state problems and 2D and 3D depletion problems. Core calculations were then performed with the AGREE HTR neutronics and thermal-fluid core simulator using super-cell cross sections. With the new history variable, the super-cell cross sections were in good agreement with the full core cross sections even for problems with significant spectrum change during fuel shuffling and depletion.

• Nuclear Engineering and Technology
• /
• 제55권11호
• /
• pp.4102-4111
• /
• 2023

In order to better perform thermal hydraulic calculation and analysis of supercritical water reactor, based on the experimental data of supercritical water, the model training and predictive analysis of the heat transfer coefficient of supercritical water were carried out by using the support vector machine (SVM) algorithm. The changes in the prediction accuracy of the supercritical water heat transfer coefficient are analyzed by the changes of the regularization penalty parameter C, the slack variable epsilon and the Gaussian kernel function parameter gamma. The predicted value of the SVM model obtained after parameter optimization and the actual experimental test data are analyzed for data verification. The research results show that: the normalization of the data has a great influence on the prediction results. The slack variable has a relatively small influence on the accuracy change range of the predicted heat transfer coefficient. The change of gamma has the greatest impact on the accuracy of the heat transfer coefficient. Compared with the calculation results of traditional empirical formula methods, the trained algorithm model using SVM has smaller average error and standard deviations. Using the SVM trained algorithm model, the heat transfer coefficient of supercritical water can be effectively predicted and analyzed.

• Korean Chemical Engineering Research
• /
• 제59권1호
• /
• pp.77-84
• /
• 2021

Plug flow reactor (PFR) 내의 과열점(hot spot) 온도를 조절하는 것은 생성물의 수득률 및 순도, 안전성 측면에서 중요하다. 본 연구에서는 더 현실에 가깝게 모델링 하기 위하여 PFR 내부의 냉각액 온도를 상태변수로 설정하고 방사 방향의 열 및 물질전달을 고려하였다. 모델은 반응물의 농도 및 온도와 냉각액의 온도 총 3개의 상태변수로 이루어져 있으며, 등온 냉각액의 유량을 조작변수로 가진다. 본 연구에서는 방사 방향의 열 및 물질전달을 고려한 제어식이 그렇지 않은 제어식보다 과열점의 온도를 set point 부근으로 더 효과적으로 유지한다는 것을 보였다. 본 연구에서 제안한 제어식은 냉각액의 온도가 반응물 온도의 약 0.7배 부근일 때 St가 1.3 이상이고 Ac/A가 2.0 이하인 조건에서 강건성을 유지하였다. 이 조건에서 반응기로 유입되는 반응물의 온도가 5% 범위에서 바뀔 때 본 연구에서 제안된 제안식을 이용하면 과열점의 온도를 set point의 1% 이내로 유지할 수 있다.

• 한국안전학회지
• /
• 제6권4호
• /
• pp.45-52
• /
• 1991

The purpose of a fatigue crack arrest desing is to prvent a fatigue fracture of machine and structure resulted from unstable crack growth. In all cases of load transfer to second elements such as stringers, doublers or flangers, crack arrest is possible; arrest occuring when the fatigue crack reaches the second element. In the present work, the possibility of crack arrest and the design criterion of fatigue crack arrest in the variable thickness plates are examined numericaiiy by using fatigue crack arrest thresthod $\Delta$K$_{th}$of SA-508 reactor vessel steel and stress intensity factor which was obtained in the previous work as a result of 3-dimensional finite element analysis for CT type variable thickness plates having discontinuous interface.e.

• Nuclear Engineering and Technology
• /
• 제17권4호
• /
• pp.247-255
• /
• 1985

본 논문은 가변구조모델추종제어(VSMFC)계 설계의 새로운 방법을 고찰한 것이다. 설계 개념은 가변구조계(VSS)와 슬라이드모드 이론을 사용하여 비선형 시변다변수계가 파라미터 변동이 있을지라도 모델추종을 정확히 하게끔 제어측이 가변구조를 갖게 하는 것이다. 본 논문의 방법을 실제 물리계에 적용할 때 컴퓨터 계산시간의 감소와 파라미터변동에 무관한 동적응답을 기대할 수 있다. 이론의 유효성을 밝히기 위해 VSMPC를 1000MWe의 불등경수형 원자로(BWE)에 적용하였다. 즉 원자로의 출력요구가 정격출력의 85∼90% 범위에서 변할 때 부하추종출력제어가 원활히 이루어지는가를 컴퓨터 시뮬레이션하였다. 12개의 비선형미분방정식으로 동특성이 주어지는 원자로에서 6차계 선형모델을 85% 정격치에서 구하고 여러범위에 걸쳐서 부하변동이 있을 때 파라미터변동을 극복하면서도 출력제어를 원활히 하는가를 연구하였다.

• Nuclear Engineering and Technology
• /
• 제53권8호
• /
• pp.2616-2628
• /
• 2021

The results of effective irradiation swelling in a wide range of burnup levels are numerically obtained for an inert matrix fuel, which are verified with DART model. The fission gas swelling of fuel particles is calculated with a mechanistic model, which depends on the external hydrostatic pressure. Additionally, irradiation and thermal creep effects are included in the inert matrix. The effects of matrix creep strains, external hydrostatic pressure and temperature on the effective irradiation swelling are investigated. The research results indicate that (1) the above effects are coupled with each other; (2) the matrix creep effects at high temperatures should be involved; and (3) ranged from 0 to 300 MPa, a remarkable dependence of external hydrostatic pressure can be found. Furthermore, an explicit multi-variable mathematic model is established for the effective irradiation swelling, as a function of particle volume fraction, temperature, external hydrostatic pressure and fuel particle fission density, which can well reproduce the finite element results. The mathematic model for the current volume fraction of fuel particles can help establish other effective performance models.