• Title/Summary/Keyword: supporting grid

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Design of Insert type supports for a tube bundle of a large diameter (큰 외경을 갖는 튜브집합체의 삽입형 지지체 설계)

  • Kim, Jae-Yong;Kim, Hyung-Kyu;Yoon, Kyung-Ho;Lee, Young-Ho;Lee, Kang-Hee
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.1373-1376
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    • 2008
  • A supporting structure for a long tube bundle of a large diameter is considered in this paper. The primary purpose of the present study is to develop a spacer grid structure for a so-called "dual cooled nuclear fuel", which has been being studied for a nuclear power uprate. The outer diameter of the fuel rod increases considerably from the conventional one. So a completely new shape of the supporting structure (spacer grid) needs to be developed. One of the challenges is to insert a supporting tube into the cross points of the grid straps. To meet a supporting performance, the load vs. displacement characteristics should be obtained. So the present study focuses on the finite element analysis technology to evaluate the characteristics through a parametric study. As a result, major influencing parameters are investigated for an optimized spacer grid design.

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Synthesis of Graphene Using Thermal Chemical Vapor Deposition and Application as a Grid Membrane for Transmission Electron Microscope Observation (열화학증기증착법을 이용한 그래핀의 합성 및 투과전자현미경 관찰용 그리드 멤브레인으로의 응용)

  • Lee, Byeong-Joo;Jeong, Goo-Hwan
    • Korean Journal of Materials Research
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    • v.22 no.3
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    • pp.130-135
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    • 2012
  • We present a method of graphene synthesis with high thickness uniformity using the thermal chemical vapor deposition (TCVD) technique; we demonstrate its application to a grid supporting membrane using transmission electron microscope (TEM) observation, particularly for nanomaterials that have smaller dimensions than the pitch of commercial grid mesh. Graphene was synthesized on electron-beam-evaporated Ni catalytic thin films. Methane and hydrogen gases were used as carbon feedstock and dilution gas, respectively. The effects of synthesis temperature and flow rate of feedstock on graphene structures have been investigated. The most effective condition for large area growth synthesis and high thickness uniformity was found to be $1000^{\circ}C$ and 5 sccm of methane. Among the various applications of the synthesized graphenes, their use as a supporting membrane of a TEM grid has been demonstrated; such a grid is useful for high resolution TEM imaging of nanoscale materials because it preserves the same focal plane over the whole grid mesh. After the graphene synthesis, we were able successfully to transfer the graphenes from the Ni substrates to the TEM grid without a polymeric mediator, so that we were able to preserve the clean surface of the as-synthesized graphene. Then, a drop of carbon nanotube (CNT) suspension was deposited onto the graphene-covered TEM grid. Finally, we performed high resolution TEM observation and obtained clear image of the carbon nanotubes, which were deposited on the graphene supporting membrane.

Vibration Analysis for a Fuel Rod Continuously Supported by a Spacer Grid (지지격자 스프링으로 다점 지지된 환형 핵연료봉의 고유 진동 해석)

  • Kang, Heung-Seok;Yoon, Kyung-Ho;Kim, Hyung-Kyu;Song, Kee-Nam
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.639-646
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    • 2000
  • Estimation for the vibration behavior of a nuclear fuel rod with its supporting structure called spacer grid has been made by the both of experimental and analytical methods in order to compare the supporting performance of two kinds of the spacer grids which have been newly developed. For the analytical method the fuel rod was modeled as a beam continuously supported by the springs of the spacer grid, and ABAQUS computer code was utilized. After a modal testing was performed for the fuel rod supported by five spacer grids, two results has been compared to justify and compensate the both methods. It has been found that the spring design of the spacer grid could give significant effect to natural frequency and vibration amplitude of the fuel rod.

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Development of A Methodology for In-Reactor Fuel Rod Supporting Condition Prediction (노내 연료봉 지지조건 예측 방법론 개발)

  • Kim, K. T.;Kim, H. K.;K. H. Yoon
    • Nuclear Engineering and Technology
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    • v.28 no.1
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    • pp.17-26
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    • 1996
  • The in-reactor fuel rod support conditions against the fretting wear-induced damage can be evaluated by residual spacer grid spring deflection or rod-to-grid gap. In order to evaluate the impact of fuel design parameters on the fretting wear-induced damage, a simulation methodology of the in-reactor fuel rod supporting conditions as a function of burnup has been developed and implemented in the GRIDFORCE program. The simulation methodology takes into account cladding creep rate, initial spring deflection, initial spring force, and spring force relaxation rate as the key fuel design parameters affecting the in-reactor fuel rod supporting conditions. Based on the parametric studies on these key parameters, it is found that the initial spring deflection, the spring force relaxation rate and cladding creepdown rate are in the order of the impact on the in-reactor fuel rod supporting conditions. Application of this simulation methodology to the fretting wear-induced failure experienced in a commercial plant indicates that this methodology can be utilized as an effective tool in evaluating the capability of newly developed cladding materials and/or new spacer grid designs against the fretting wear-induced damage.

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Structural Design Considerations on the Spacer Grid Assembly of PWR Nuclear Fuel (경수로 핵연료 지지격자체 구조설계에 대한 소고)

  • Song, Kee-nam
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.7 no.3
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    • pp.54-60
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    • 2011
  • A spacer grid, which supports nuclear fuel rods laterally and vertically with a friction grip, is one of the most important structural components in a PWR fuel. The form of grid strap and supporting parts such as grid spring and dimple is known to be closely related with the mechanical/structural performance of spacer grid and nuclear fuel assembly. In this study, reviewing various research results for enhancing the performance of the spacer grid, some structural design considerations and research directions on the spacer grid assembly are suggested for further study.

The Effect of Water Flow on Fretting Wear of the Nuclear Fuel Cladding Tubes against the Supporting Grids (핵연료 피복관과 지지격자 사이에 발생하는 프레팅 마멸에 미치는 유동의 영향)

  • Lee, Young-Ze;Kim, Jin-Seon;Park, Se-Min;Park, Dong-Shin
    • Tribology and Lubricants
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    • v.24 no.4
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    • pp.186-189
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    • 2008
  • The flow induced vibration in the nuclear fuel assembly causes the fretting wear between the fuel cladding tubes and the supporting grids. The reduction in tube thickness due to the fretting wear could be related to the serious damage on nuclear fuel assembly. In this paper, the effect of the water flow on fretting wear of nuclear fuel cladding tube against supporting grid was investigated through the fretting wear tester with water spout equipment. The test results were compared with the data conducted in the stationary water. At stationary water environment the wear debris was trapped between fretting surfaces, and then the fretting wear occurred by three-body abrasion. However, in the case of water flow, the two-body abrasive wear was the dominant wear mechanism, because the wear debris was easily removed by water flow.

Service Development Tool for Micro Grid Common Platform (마이크로 그리드용 공통플랫폼 서비스 개발 도구)

  • Lee, Hyun-Hee;You, Dae-Sang
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.19 no.6
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    • pp.1455-1461
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    • 2015
  • Micro Grid is a new concept of electrical grid to solve several problems of Mega-Grid and it is under research and development at the national level around the world. With this background, Micro Grid Common Platform has been developed for interoperability technology of devices-systems in Micro Grid and securing enabler for new market. For supporting business models, Micro Grid Common Platform provides electric power information to Third-Party licensee via Open API function. Licensee, who want to develop electric power application by connecting to Micro Grid Common Platform, needs IDE(Integrated Development Environment) for service development and distribution. The paper proposes a service development tool for developing applications of Micro Grid Common Platform as a PaaS (Platform as a Service).

Shape Modification for Decreasing the Spring Stiffness of Double-plated Nozzle Type Spacer Grid Spring (이중판 노즐형 지지격자 스프링의 지지 강성감소를 위한 형상 개선)

  • Kang, H.S.;Song, K.N.;Lee, J.H.;Lee, K.H.
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.400-405
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    • 2001
  • Nozzle of the double-plated grid plays the role of the spring to support a fuel rod as well as to provide the coolant path in grid. The nozzle was known to be necessary to reduce the spring stiffness for supporting performance. In this study the contact analysis between the fuel rod and the nozzle type spacer grid was performed by using ABAQUS standard to propose the preferable shape in tenn of spring performance. Two small cuts at the upper and lower part of the nozzle appeared to have a minor effect in decreasing the nozzle stiffness. A long slot at the center of the nozzle was turned out not only to decrease the spring constant as desired but also to increase the elastic displacement.

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FRETTING WEAR OF A SPRING SUPPORTED TUBE SUBJECTED TO TRANSVERSE VIBRATION

  • Kim, Hyung-Kyu;Yoon, Kyung-Ho;Lee, Young-Ho;Ha, Jae-Wook;Kim, Seock-Sam
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.195-196
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    • 2002
  • Studied is fretting wear behaviour of transversely vibrating tube which is supported by springs and dimples. This simulates the fuel rod fretting due to flow-induced vibration in a nuclear reactor. The contact between spacer grid springs and fuel cladding tubes arc brought into focus in this paper. From the mechanical viewpoint, a concave contact shape of spring is considered to perform a wider distribution of the contact stress. Sliding/impacting experiments are conducted in air at room temperature with the conditions of positive contact force and gap existence to accommodate the mechanical condition between the fuel rod and the grid spring during reactor operation. It is found that wear region is separated and wear volume becomes larger as the supporting condition becomes poorer. Spring and dimple cause similar wear.

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