Maintenance of Process Instrumentation in Nuclear Power Plants

This book is written for the instrumentation and control engineers, technicians, and managers in nuclear power plants. It focuses on process temperature and pressure sensors and the veri?cation of these sensors’ calibration and response time. It also provides examples of typical problems and solutions with temperature and pressure measurements in nuclear power plants. Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1. 1 Reference Plant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1. 2 On-Line Monitoring of Process Instruments Calibration . . . . . . . . . . 3 1. 3 Dynamic Testing of Pressure Transmitters and Sensing Lines . . . . . . 3 1. 4 On-Line Detection of Venturi Fouling . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1. 5 Measuring the Vibration of Reactor Internals . . . . . . . . . . . . . . . . . . . . 8 1. 6 Detecting Core Flow Anomalies . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . 10 1. 7 CANDU Reactor Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 1. 8 In-Situ Response-Time Testing of Temperature Sensors . . . . . . . . . . . 12 1. 9 Testing Cables In-Situ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 1. 10 Automated Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2 Origins of This Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2. 1 Collaborative R&D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2. 2 Government R&D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2. 3 Utility R&D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 2. 4 IAEA Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2. 5ISA and IEC Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 3 Maintenance of Nuclear Plant Instrumentation . . . . . . . . . . . . . . . . . . . 27 4 Nuclear Plant Temperature Instrumentation . . . . . . . . . . . . . . . . . . . . . 29 4. 1 History of RTDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 4. 2 Nuclear-Grade RTDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 4. 3 Nuclear Plant Temperature Measurement Terminology . . . . . . . . . . . 34 4. 4 Problems with Nuclear-Grade RTDs . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 4. 4. 1 Dynamic Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 4. 4. 2 Failure of Extension Leads . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 4. 4. 3 Low Insulation Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 4. 4. 4 Premature Failure . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . 44 4. 4. 5 Wrong Calibration Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 X Contents 4. 4. 6 Loose or Bad Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The resurgence of the nuclear power industry at a time when the nuclear plant I&C workforce is diminishing due to aging and retirements has been the motivation for writing this book. This book compiles 30 years of practical knowledge gained by the author and his staff in testing the I&C systems of nuclear power plants around the world. It focuses on process temperature and pressure sensors and the verification of these sensors calibration and response time.

In spite of great advances in electronics, computers, and measurement technologies, important process parameters such as temperature and pressure are still measured with conventional sensing techniques found in RTDs, thermocouples, and conventional pressure and differential pressure sensors. Furthermore, no improved technology providing comparable performance is currently on the horizon. Therefore, it is important to understand how these sensors function and the testing techniques for verifying their performance. This book is intended to help provide this understanding.