J — v ft INIS-mf—15B1 7 INTERNATIONAL ATOMIC ENERGY AGENCY NUCLEAR ELECTRIC Ltd. Monitoring and Diagnosis Systems to Improve Nuclear Power Plant Reliability and Safety PROCEEDINGS OF THE SPECIALISTS’ MEETING JOINTLY ORGANISED BY THE IAEA AND NUCLEAR ELECTRIC Ltd. AND HELD IN GLOUCESTER, UK 14-17 MAY 1996 NUCLEAR ELECTRIC Ltd. 1996 VOL INTRODUCTION The Specialists ’ Meeting on Monitoring and Diagnosis Systems to Improve Nuclear Power Plant Reliability and Safety, held in Gloucester, UK, 14 - 17 May 1996, was organised by the International Atomic Energy Agency in the framework of the International Working Group on Nuclear Power Plant Control and Instrumentation (IWG-NPPCI) and the International Task Force on NPP Diagnostics in co-operation with Nuclear Electric Ltd. The 50 participants, representing 21 Member States (Argentina, Austria, Belgium, Canada, Czech Republic, France, Germany, Hungary, Japan, Netherlands, Norway, Russian Federation, Slovak Republic, Slovenia, Spain, Sweden, Switzerland, Turkey, Ukraine, UK and USA), reviewed the current approaches in Member States in the area of monitoring and diagnosis systems. The Meeting attempted to identify advanced techniques in the field of diagnostics of electrical and mechanical components for safety and operation improvements, reviewed actual practices and experiences related to the application of those systems with special emphasis on real occurrences, exchanged current experiences with diagnostics as a means for predictive maintenance. Monitoring of the electrical and mechanical components of systems is directly associated with the performance and safety of nuclear power plants. On-line monitoring and diagnostic systems have been applied to reactor vessel internals, pumps, safety and relief valves and turbine generators. The monitoring techniques include nose analysis, vibration analysis, and loose parts detection. Complicated signal analysis may be involved, e g. conversion into the frequency domain, application of correlation and pattern recognition methods, etc. Comparison to reference or “signature ” information and trending are important tasks. More recently, expert system methods have been introduced in order to improve the performance of such systems. The advantages of performance, therefore, cause computers to be increasingly used to enhance monitoring and diagnostic functions to make the methods applied more user friendly and to achieve the necessary user acceptance. Since the main goal of the diagnosis systems is the early detection of a developing mechanical and electrical deficiency, the importance for maintenance and inspection is obvious. Experience shows that due to findings of the on-line diagnosis systems, the preparation of repair actions can be considerably improved, and maintenance and inspection times can be reduced. Monitoring and diagnosis systems can be considered as a type of operator support systems (OSS) which provide more processed, integrated information than it is available from conventional instrumentation. They guide and advise operators and enable them to make better strategic decisions during both normal and abnormal operation. They also provide a capability for supervisory management during emergency conditions. Several factors have led to increased interest in operator support systems in NPPs like e g.: - Increasing complexity of nuclear power plants and increasing demands for higher productivity and safety, require the operator to be more aware of plant conditions so that correct actions can be taken; - Many of the originally installed plant information systems have come to the end of their lives. The need for replacement of these systems has stimulated a significant upgrading of their functionality for operator support; - From a technology viewpoint, developments in computers, such as in artificial intelligence, neural networks and display technology have identified opportunities for operator support that were not possible in the past. Some types of operator support systems received special emphasis during the meeting. a) Fault detection and diagnosis. This alerts operators to problems and aids diagnosis before the normal alarm limits are reached. This function is also valuable when simple alarm monitoring is impractical or where complex situations cannot be revealed by alarms or alarm logic. Examples are: _ V _ 1 - Fault monitoring of protection logic and associated electrical supplies, fuel pin failure detection and prediction; - Detection and identification of leakage, e g., in the primary circuit; - Model based fault detection for components (e g. pre-heaters) and measurement loops. b) Performance monitoring. This function calculates and monitors the efficiency and optimum operation of main pumps, turbine, generator, condenser steam generators, preheaters, etc. to detect developing anomalies. The reactor thermal energy as well as heat, electricity and mass heat balance can be calculated. c) Maintenance support. Several systems exist for specialists and maintenance staff. For example, vibration monitoring and analysis, loose parts monitoring and materials stress monitoring. Systems for on-line diagnosis were attempted in the early 1980s following initial developments at the Hal den project. The actual use of such systems was limited due to a number of reasons, including: - Complexity; - Inability to assure completeness of accident sequences and the combination of accident sequences; - The large effort needed for maintenance. The availability of fast, low cost computers, as well as new technologies such as expert systems have, however rekindled interest in on-line diagnosis and several such systems have been implemented or are under development. A wide range of monitoring diagnostic systems are under development and trial at many NPPs. Advanced diagnostic systems using expert system technology and modem computer technology have been attempted and are under development. Special attention was paid during the meeting to advanced techniques which can potentially improve the ability of monitoring and diagnosis systems to enhance nuclear power plant reliability and safety, like neural network, for example. In order to facilitate a structured discussion and not to omit important areas of interest, papers on the following subjects were considered to be within the scope of the Specialists ’ Meeting: - Diagnostic and monitoring systems: state of the art, practical experience and new developments; - Impact of diagnostic systems on NPP performance and safety; - Advanced techniques for safety and operational improvements; - Safety and licensing consideration, e g. matching of new systems to safety requirements, extending plant life cycle, applicability of existing safety standards. - 3 — CONTENTS INTRODUCTION Session I CURRENT APPROACHES Chairpersons: Mr. R.E. Uhrig, USA Mr. V. Beckett, UK. Mr. K. Welboume, UK. Enhancing the Functionality of Reactor Protection Systems to Provide Diagnostic and Monitoring Information: The IS AT ™ Approach J.A. Baldwin, C.D. Jones, BJ. Rowe Moderator Behaviour and Reactor Internals Integrity at Atucha 1 NPP S. Berra, M. Chocron, M. Guala, P.Herzovich, A. Lorenzo, Ma. del C. Rqffo Calderon , G. Urrutia Experience with an Expert System Technology for Real-Time Monitoring and Diagnosis Q.B. Chou, J. Mylopoulos, J. Opala Detection of Leaks in Steam Lines by Distributed Fibre-Optic Temperature Sensing (DTS) N.G. Craik Leak Detection System for RBMK Coolant Circuit Ju. M. Cherkashov, B.P. Strelkov, Yu. V. Korolev, A.P. Eperin, E.P. Kozlov, L.A. Belyanin, V.N. Vanukov Fault Detection Using Parameter Transfer Functions 7. Salamun, B. Mavko, A. Stritar Reliability of Operating WER Monitoring System M.A. Yastrebenetsky, VM. Goldrin,A.V. Garagulya Session 2 EXPERIENCES WITH MONITORING AND DIAGNOSIS SYSTEMS Chairpersons: Mr. M. DeVemo, Canada Mr. F. Binns, UK. Condition Monitoring of Rotormachinery in Nuclear Power Plants U. Sudmersen, J. Runkel, A. Vortriede, W. Reimche, D. Stegemann External Vibration Measurement of Reactor Components S.A. Rogers, J. Sugden Prophylactic and Thermovision Measurements of Electric Machines and Equipment R Jedlicka, L. Brestovansky Systems for Noise Diagnosis ofWWER Nuclear Power Plants G. Por TG 220 Mw Hydraulic Control System Diagnostic A. Svabak Diagnostic and Monitoring Systems Produced in VUJE G. Oksa, J. Bahna, V. Murin, P. Kucharek, $. Smutny 3 - Session 3 IMPACT ON NPP PERFORMANCE AND SAFETY Chairpersons: Mr. U. Sudmersen, Germany Mr. D.W. Anderson, UK. Data Fusion and Sensor Management for Nuclear Power Plant Safety 0. Cifticioglu, £. Tiirkcan Canadian CANDU Plant Data Systems for Technical Surveillance and Analysis M. DeVemo, J. de Grosbois, M Bosnich, H. Pothier, C. Xian Process Variables Consistency at Atucha 1 NPP E. Arostegui, Aparicio, P. Herzovich, G. Urrutia, J. Wenzel Session 4 ADVANCED TECHNIQUES Chairpersons: Ms. J. Baldwin, UK. Mr. G.B. Moutiy, UK. Instrument Surveillance and Calibration Verification Through Plant Wide Monitoring Using Autoassotiative Neural Networks DJ. Wrest, J.W. Hines, REUhrig Development of Nuclear Power Plant Monitoring System with Neural Network Using On-line PWR Plant Simulator K. Nabeshima, K. Suzuki, S. Nose, fC Kudo An Object-Oriented-Database-System to Assist Control Room Staff G.H. Schildt New Technologies in Nuclear Power Plant Monitoring and Diagnostics E. Tiirkcan, 0. Ciftcioglu, J.P. Verhoef General Knowledge Structure for Diagnosis T.S. Brendeford Advanced Software Tools for Digital Loose Part Monitoring Systems Y. Ding Session 5 PANEL