atw 2019-02

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atw Vol. 64 (2019) | Issue 2 ı February ENVIRONMENT AND SAFETY 96 started by the connected protection and control signals, and the operation history of these safety systems is recorded on the SOER/Alarm List. Thus, as a means to analyze system behaviors, this research focuses on the SOER/Alarm List as it contains information on actual abnormal events that took place in the plants. Basically, the introduced method determines the behavior adequacy of systems in the following manners: two comparable events are selected and the SOER/Alarm List of each event is collected. Then, one SOER/Alarm List is set as a standard point, and the other List is moved towards the standard point to check whether their alarm names are matching. The existing string-searching algorithms, including Sing-Pattern Algorithm, Native String Search, Knuth- Morris-Pratt Algorithm, calculates the percentage of matching words or sentences in the TEXT being analyzed as compared to a reference text.[2, 3] However, if SOER/Alarm lists are compared with each other using the existing string-searching algorithms, the result would simply be the mere comparison of words or sentences, rather than an insights into plant’s physical phenomena (for example, dead band of alarming actuation signal, differences caused by system scan times, etc.) and deeper understanding of the conditions (for example, dropping of rods in the sequence of number 1, 2 and 3, as compared to 2, 3, and 1). Drawing such a simple percentage does not help anyone to understand actual phenomena that took place in the plants. To address this situation, this research p aper intends to introduce an analysis method of comparing the SOER/Alarm lists to get the similarity analysis of system behaviors during the plant abnormal conditions. The stages of the SOER/Alarm list comparative analysis are as follows: pp Compare and analyze the number of matching alarm types between the lists; pp Analyze the weighted value to be applied on the similarity results; and pp Compensate considering the total number of alarms on the SOER/ Alarm List. Considering the above conditions, a computing program has been developed in order to conduct the behavior similarity analysis on the abnormal plant conditions. When the SOER/ Alarm Lists recorded during the abnormal conditions are registered into the program, it generates the following analysis based on Microsoft’s Excel as well as Visual-Basic; pp Removal of reset alarms on the SOER/Alarm List; pp Acquiring selective reset information on the SOER/Alarm List; pp Arranging alarm names by time on the SOER/Alarm List; pp Arranging systems by time on the SOER/Alarm List; and pp Data processing programming on the SOER/Alarm List. 3) The result of case analysis to verify and utilize the computer program Two similar events were selected that occurred in the plants with same reactor type to apply the SOER/Alarm List methodology, which is featured in this research. One event involved a reactor trip caused by a single reactor coolant pump (RCP) shutting down, while the other involved a reactor trip by two RCPs stopping. Both the power plants had a 2-loop system and the RCPs stopped in a different loop in each case. The result generated by using the SOER/Alarm List methodology and tools to analyze system behaviors Order System Weighted Value Compensation Factor Result 1 13.8kV Power System - - - 2 Reactor Coolant System 0 % 0.5 0 % 3 Reactor Trip Switch Gear System 100 % 1 100 % 4 Control Element Drive Mechanism 100 % 1 100 % 5 Main Turbine system 87.18 % 0.886 77.27 % 6 Turbine Hydraulic Fluid 100 % 1 100 % 7 Steam Bypass Control System 100 % 1 100 % 8 Reactor Power Cutback system 100 % 1 100 % 9 Main Power System 100 % 1 100 % 10 Feed Water System 100 % 1 100 % 11 Reactor Protection System 75 % 0.8 60 % 12 Main Steam System 78.26 % 0.958 75 % | | Tab. 2. Analysis result on the system adequacy and similarity of two events. of two events is featured in following Table 2. The analysis on the behaviors and similarity of these two events concluded that their system behaviors during the transient status were approximately 82.93 % similar. Moreover, additional analysis on the systems with dissimilar behaviors revealed that there was one valve out of many in the main steam bypass system that was abnormal. Based on the result of behavior and similarity analysis of each system, the methodology and analysis tools were verified to be useful in analyzing behavior adequacy and similarity of plant systems. As the previously mentioned result indicates, the method of analyzing the system behaviors by comparing similar events not only helps in determining the behavior adequacy of systems according to its design, but also in identifying the system with abnormal behavior and conducting cause analysis so that it can be used for the plant maintenance activities. 3 Conclusion The analysis result generated by using the suggested methodology in this research paper showed that these two events showed a high level of similarity in terms of their behaviors during abnormal conditions. Furthermore, the result found that system behaviors were adequate, while few systems did not behave as it is supposed to have according to its design. As such, by utilizing the method to analyze similarities of events that occurred during abnormal situations, the behavior adequacy of plant systems could be determined as well as identify the systems with abnormal behaviors and gain insights for cause analysis. The computer program developed as part of the research also proved to be useful for the behavior analysis of plant systems in abnormal conditions. Thus, the expectation of the safer operation of the plants would be possible when using the analysis methodology; it offers a prompt and standardized behavior adequacy analysis as well as a cause analysis of the systems identified to have abnormal behaviors. 4 Further study In order to use the method suggested in this research as an analysis tool in a more effective and prompt way, it would be necessary to establish standards for various abnormal situations and further verify this method. After Environment and Safety Research for the Adequacy Analysis of Plant System Behaviors During Abnormal Conditions ı Yeong Jin Yu , Ho Cheul Shin and Jae Heung Lee
atw Vol. 64 (2019) | Issue 2 ı February establishing the standards and conducting additional verification with other similar events, it would be necessary to create a foundation so that system behaviors during various plant abnormal events are promptly and effectively analyzed and determined, and the result can be used for the plant maintenance activities. References [1] American National Standard Revision and Addendum to Nuclear Safety Criteria for the Pressurized water Reactor Plants, ANSI N18.2, (1973). [2] Aoe, J-I.: Computer algorithms: string pattern matching strategies, IEEE Computer Society Press, (1994). [3] Knuth D.E., Morris(jr) J.J., Pratt V.R.: Fast pattern matching in strings, SLAM Journal on Computing 6(1) : 323-350, (1977). Authors Yeong Jin Yu Ho Cheul Shin Korea Institute of Nuclear Safety (KINS) 62 Gwahak-ro, Yu-seong, Daejeon, Korea, 34142 Jae Heung Lee, Ph.D Computer Engineering Hanbat National University Rep. of Korea Advertisement ENVIRONMENT AND SAFETY 97 Ihre schriftliche Bewerbung richten Sie bitte bis zum 20.03.2019 an: Dekan der Fakultät für Georessourcen und Materialtechnik der RWTH Aachen, Univ.-Prof. Dr. Peter A. Kukla, 52056 Aachen. Gerne können Sie Ihre Bewerbung auch per E-Mail an: dekanat@fb5.rwth-aachen.de senden. Bitte beachten Sie, dass Gefährdungen der Vertraulichkeit und der unbefugte Zugriff Dritter bei einer Kommunikation per unverschlüsselter E-Mail nicht ausgeschlossen werden können. Auf Wunsch kann eine Teilzeitbeschäftigung ermöglicht werden. Die RWTH Aachen University ist als familiengerechte Hochschule zertiiziert und verfügt über ein Dual Career Programm. Wir wollen an der RWTH Aachen University besonders die Karrieren von Frauen fördern und freuen uns daher über Bewerberinnen. Frauen werden bei gleicher Eignung, Befähigung und fachlicher Leistung bevorzugt berücksichtigt, sofern nicht in der Person eines Mitbewerbers liegende Gründe überwiegen. Bewerbungen geeigneter schwerbehinderter Menschen sind ausdrücklich erwünscht. W3 Universitätsprofessur Untertägige Raumplanung und Endlagerkonzepte Fakultät für Georessourcen und Materialtechnik Zum nächstmöglichen Zeitpunkt wird eine Persönlichkeit gesucht, die dieses Fach in Forschung und Lehre vertritt. Es sind Aufgaben in den genannten Themenbereichen zu erfüllen: - Endlagerkonzepte für verschiedene Wirtsgesteine - Langzeitsicherheitsanalysen, Langzeitsicherheitsnachweise inkl. Nachweiskonzepte - Freisetzungsverhalten, Stofftransport und Ausbreitung - Regulatorische Anforderungen für die Verbringung von Abfällen im geologischen Untergrund - Untertägige Raum- und Infrastrukturplanung sowie Modellierung der Nutzung untertägiger Räume - Monitoring von Endlagern und Geosystemen Voraussetzungen sind ein abgeschlossenes Universitätsstudium, Promotion und zusätzliche wissenschaftliche Leistungen, die durch eine Habilitation, im Rahmen einer Juniorprofessur, einer wissenschaftlichen Tätigkeit an einer Hochschule, Forschungs- einrichtung, in Wirtschaft, Verwaltung oder einem anderen gesellschaftlichen Bereich erbracht wurden. Des Weiteren werden didaktische Fähigkeiten erwartet. Den Bewerbungsunterlagen sollen Belege über Lehrerfolge beigefügt werden. Bitte füllen Sie zusätzlich den Bewerbungsfragebogen aus, die Datei nden Sie im Internet unter http://www.fb5.rwth-aachen.de/Berufung Die Fakultät sucht bevorzugt eine Pe Die Fakultät sucht bevorzugt eine Perönlichkeit mit einer Ausbildung in den Ingenieuroder Geowissenschaften in den Themenbereichen Bergbau, Rohstoffgewinnung oder Endlagerung mit nachgewiesenen, fundierten Kenntnissen und Erfahrungen im Themenfeld der Entsorgung radioaktiver Abfälle. Environment and Safety Research for the Adequacy Analysis of Plant System Behaviors During Abnormal Conditions ı Yeong Jin Yu , Ho Cheul Shin and Jae Heung Lee
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