atw - International Journal for Nuclear Power | 06.2021

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atw Vol. 66 (2021) | Issue 6 ı November ENVIRONMENT AND SAFETY 36 Imprint Official Journal of Kerntechnische Gesellschaft e. V. (KTG) Publisher INFORUM Verlags- und Verwaltungsgesellschaft mbH Robert-Koch-Platz 4, 10115 Berlin, Germany Phone: +49 30 498555-33 www.nucmag.com @atw_Journal @atw-international-journal-for-nuclear-power General Manager Dr. Thomas Behringer unnecessary model enlargement. Therefore, even in such case, it is necessary to select equipment that has a significant influence on seismic events, and applying the equipment selection methodology proposed in this paper can contribute to the simplification of the SPSA model and the accuracy of the analysis of the quantitative results, and minimize unnecessary analysis. Therefore, it is expected that uncertainty errors will be minimized. References [1] Seismic Probabilistic Risk Assessment Implementation Guide. USA: Electric Power Research Institute; 2013, 3002000709. [2] Standard for Level 1/Large Early Release Frequency Probabilistic Risk Assessment for Nuclear Power Plant Applications. USA: The American Society of Mechanical Engineers; 2009, ASME/ANS Ra-SA-2009. [3] White Paper: Criterion for Capacity-based Selection of SSCs for Performing Fragility Analysis in a Seismic Risk-based Evaluation. USA: Nuclear Energy Institute; 2012. [4] FTeMC Quick Guide Fault Tree Top Event Probability Evaluation Using Monte Carlo Simulation. Korea: Korea Atomic Energy Research Institute; 2017, KAERI-ISA- memo-FTeMC-01, Rev. 1. [5] Development and Validation of the Seismic Probabilistic Safety Assessment Software PRASSE. Korea: Korea Atomic Energy Research Institute; 2012, KAERI/TR-4649. [6] Probabilistic safety assessment for seismic events. IAEA; 1993, TECDOC-724. [7] M Vermaut, Ph Monette P Shah R.D Campbell, Methodology and results of the seismic probabilistic safety assessment of Krško Nuclear Power Plant, Nuclear Engineering and Design, 2 May 1998, Volume 182, Issue 1, Pages 59-72 [8] Risk Assessment of Operational Events Handbook Volume 2 – External Events. USA: Nuclear Regulatory Commission; 2008, Revision 1.01 [9] Seismic Evaluation Guidance Screening, Prioritization and Implementation Details (SPID) for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic. USA: Electric Power Research Institute; 2013, 1025287 [10] A Methodology for Analyzing Precursors to Earthquake- Initiated and Fire-Initiated Accident Sequences. USA: Nuclear Regulatory Commission; 1998, NUREG/CR-6544. [11] Surry Seismic Probabilistic Risk Assessment Pilot Plant Review. USA: Electric Power Research Institute; 2010, 1020756. [12] Identification of External Hazards for Analysis in Probabilistic Risk Assessment. USA: Electric Power Research Institute; 2011, 1022997. Authors Editor in Chief Christopher Weßelmann +49 2324 4397723 christopher.wesselmann @nucmag.com Advertising and Subscription info@nucmag.com Editor Nicole Koch +49 163 7772797 nicole.koch @nucmag.com Managing Editor Nicolas Wendler +49 30 498555-21 nicolas.wendler @nucmag.com Junghyun Ryu PhD Candidate Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea yarya@hanyang.ac.kr Editorial Advisory Board Frank Apel Erik Baumann Dr. Erwin Fischer Carsten George Eckehard Göring Dr. Florian Gremme Dr. Ralf Güldner Carsten Haferkamp Dr. Anton Kastenmüller Prof. Dr. Marco K. Koch Herbert Lenz Jan-Christan Lewitz Andreas Loeb Dr. Thomas Mull Olaf Oldiges Dr. Tatiana Salnikova Dr. Andreas Schaffrath Dr. Jens Schröder Norbert Schröder Thomas Seipolt Prof. Dr. Jörg Starflinger Dr. Brigitte Trolldenier Dr. Walter Tromm Dr. Hans-Georg Willschütz Dr. Hannes Wimmer Layout zi.zero Kommunikation Antje Zimmermann Berlin, Germany Printing inpuncto:asmuth druck + medien gmbh Buschstraße 81, 53113 Bonn, Germany Price List for Advertisement Valid as of 1 January 2021 Published bimonthly, 6 issues per year Germany: Per issue/copy (incl. VAT, excl. postage) 32.50 € Annual subscription (incl. VAT and postage) 183.50 € All EU member states without VAT number: Per issue/copy (incl. VAT, excl. postage) 32.50 € Annual subscription (incl. VAT, excl. postage)183.50 € EU member states with VAT number and all other countries: Per issues/copy (no VAT, excl. postage) 30,37 € Annual subscription (no VAT, excl. postage) 171.50 € Copyright The journal and all papers and photos contained in it are protected by copyright. Any use made thereof outside the Copyright Act without the consent of the publisher, INFORUM Verlags- und Verwaltungsgesellschaft mbH, is prohibited. This applies to repro ductions, translations, micro filming and the input and incorpo ration into electronic systems. The individual author is held responsible for the contents of the respective paper. Please address letters and manuscripts only to the Editorial Staff and not to individual persons of the association's staff. We do not assume any responsibility for unrequested contributions. Signed articles do not necessarily represent the views of the editorial. ISSN 1431-5254 Junghyun Ryu is a doctoral student in the Department of Nuclear Engineering at Hanyang University. He works in FNC Technology in South Korea. Prof Dr Moosung Jae Professor at Hanyang University, South Korea jae@hanyang.ac.kr Moosung Jae is Professor of Department of Nuclear Engineering, Hanyang University, Seoul, Korea. He is now Director of MUR Risk Assessment Group ( MURRG Center) at HYU. Prior to joining Hanyang University, Seoul, Korea, he had worked for as a senior researcher for Korea Atomic Energy Research Institute (KAERI). He received B.S. and M.S. in Nuclear Engineering fromSeoul National University and Ph.D. in Nuclear Engineering from University of California, Los Angeles, USA (1992). Now he is a member of INSAG (International Nuclear Safety Group), IAEA as well as a member of the National Academy of Engineering of KOREA. Environment and Safety Equipment Selection Methodology of Seismic Probability Safety Assessment for Nuclear Power Plant ı Junghyun Ryu and Moosung Jae
atw Vol. 66 (2021) | Issue 6 ı November Experimental Study of Convective Heat Transfer Through Fuel Pins of a Nuclear Power Plant Atif Mehmood, Ajmal Shah, Mazhar Iqbal, Ali Riaz, Muhammad Ahsan Kaleem and Abdul Quddus Cylindrical heat sources are used to model the fuel pins in the reactor core of a nuclear power plant and also in the spent fuel storage. This research was aimed at studying convection through slender cylinders arranged in a square array, placed inside a ventilated enclosure. Four cylindrical heat sources were manufactured, each having L/D ratio of 6.1. These heat sources were placed inside an enclosure which had one inlet and three outlets. At first, optimum configuration of outlets for heat transfer was found by keeping the inlet speed of air and heat flux constant. This optimum outlet configuration was then used to study the effect of changing heat flux on heat transfer. Speed of air was kept constant at 0.7 m/s throughout this study. The heat flux was changed, ranging from 79.83 W/m 2 to 513.59 W/m 2 and Rayleigh number changed accordingly from 2.093x10 9 to 8.575x10 9 . It was observed that by increasing Rayleigh number, Nusselt number decreased along with the heat transfer. 1 Introduction Convective heat transfer is one of the important areas of research in heat transfer. Efficient heat transfer from heat sources has been an important topic of research over the past few years. Cylindrical heat sources are widely used in many industries such as building, solar and nuclear industry. In nuclear industry, fuel pins inside reactor core and spent fuel storage can be modeled as cylindrical heat sources with convective fluid flowing around them. Due to such vast applications and importance, researchers around the world have studied heat transfer through cylindrical heat sources both experimentally and computationally to solve issues related to temperature control. There are many configurations in which convective heat transfer through cylindrical heat sources can be studied. The medium through which the heat is transferred, could be finite or infinite, the heat sources could be single or multiple, and could be ranged in a horizontal, vertical or inclined orientation, the convective fluid could be air, water or any other suitable fluid, the type of convection could be free, forced or mixed convection and the enclosure could be ventilated or non-ventilated. All these different types of configurations have been studied previously. Popiel [1] reviewed heat transfer through slender cylinders in which he used the data put forth by Cebeci [2] and differentiated between heat transfer through thick and slender cylinders. This is important since thick cylinders can be approximated as flat plates and thin cylinders cannot. Griffiths and Davis [3] studied convection in 1922, where they studied vertical cylinders in isothermal condition. They did experiments on various cylinders, keeping their diameters constant and varying the length of the cylinders and determined the average Nusselt numbers. Later on, Morgan [4] used that data to find two correlations, which are valid over their respective ranges of dimensionless number. Fujii et al. [5] did experiments on isothermal vertical cylinders, using three different fluids i.e. water (Pr = 5), mobiltherm oil (Pr = 100) and spindle oil (Pr = 100). Separate correlations were then developed for the local Nusselt numbers for each of the fluids used. Jarral and Campo [6] carried out an experimental study, using isoflux boundary condition and determined local Nusselt numbers in terms of Rayleigh number for air. They did their experimentation using cylinders with three different slenderness ratios. Ali Riaz et al. [7] performed experiments on vertical cylinders and horizontal cylinders to find the heat transfer coefficients. The Nusselt number was observed to decrease from the bottom of the cylinder, towards the top, up to a certain point after which it started to increase. The reason behind this is that thermal boundary layer thickness increases from bottom to top of the cylinder. In the horizontal configuration, however, the local Nusselt number was least at the outlet and maximum at the inlet. Arshad et al. [8] performed experiments with natural convection at high Rayleigh numbers using nine cylinders in a 3x3 array placed vertically and enclosed inside an enclosure. It was observed that surface temperatures increased up to a specific point and then decreased, this is attributed to mixing, which results in increase in heat transfer. K. Hata et al. [9] studied heat transfer through natural convection in laminar region, using vertical rods placed in a 7x7 array placed in liquid sodium. The effect of pitch-to-diameter (P/D) ratio, array size, bundle geometry and Rayleigh number on heat transfer, was observed by calculating Nusselt number under different conditions. Yuji Isahai and Naozo Hattori [10] worked on a numerical study of heat transfer through natural convection in a heated rod bundle, that was placed vertically in an equilateral triangle configuration inside an enclosure. They used a total of 19 cylinders in their study in a hexagonal formation, with the center cylinder dedicated for instrumentation. Five different P/D ratios were studied which varied between minimum of 1.1 to maximum of 7.0. Abdul Jabbar Khalifa and Zaid Ali [11] studied heat transfer through natural convection in single and in multiple cylinders. For multiple cylinder configuration, they used nine cylinders in a 3 x 3 array, out of which only three cylinders were heated. A square array configuration was used for cylinders having a P/D ratio of 2. The fluid used for heat transfer was water. Heat flux was varied and its effect was studied. K. Tehseen et al. [12] performed a numerical study, using ANSYS, to find the effects of different orientations of core on heat transfer along bare circular tubes and tube bundles. They found that the heat transfer was directly proportional to the heated length and inversely proportional to the inside diameter of the tube. 37 RESEARCH AND INNOVATION Research and Innovation Experimental Study of Convective Heat Transfer Through Fuel Pins of a Nuclear Power Plant ı Atif Mehmood, Ajmal Shah, Mazhar Iqbal, Ali Riaz, Muhammad Ahsan Kaleem and Abdul Quddus
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