Wireless Sensors for Equipment and Process Condition Monitoring in Nuclear Power Plants

Transcription

1 Wireless Sensors for Equipment and Process Condition Monitoring in Nuclear Power Plants H.M. Hashemian B.D. Shumaker President Systems Engineer AMS Corporation AMS Corporation AMS Technology Center AMS Technology Center 9111 Cross Park Dr., Bldg. A 9111 Cross Park Dr., Bldg. A. Knoxville, TN Knoxville, TN G.W. Morton C.J. Kiger Software Development Manager Systems Engineer AMS Corporation AMS Corporation AMS Technology Center AMS Technology Center 9111 Cross Park Dr., Bldg. A 9111 Cross Park Dr., Bldg. A. Knoxville, TN Knoxville, TN KEYWORDS Condition Monitoring, Cyber Security, Nuclear Power Plant, Wireless Sensors ABSTRACT Equipment condition monitoring in industrial processes depends on measurement of temperature, vibration, pressure, strain, humidity, and other parameters. Often, no sensors are installed on or near the equipment to provide these measurements for condition monitoring applications. Of course, new sensors can be installed on or near the equipment or the process; but the wiring costs would be prohibitive. Wireless sensors provide a cost effective alternative and are being used more and more for equipment and process condition monitoring and other applications in a variety of industrial processes. Although these efforts have been successful, a number of challenges must be resolved to establish the foundation for the widespread use of wireless technologies for industrial applications. These challenges are being addressed through a number of research and development (R&D) activities currently underway at vendor facilities, universities, government laboratories, and other organizations. These R&D activities are concentrated not only on resolution of wireless technology issues such as reliability, security, battery life, and latency, but also on implementation and other challenges such as installation issues, electromagnetic and radio frequency interference (EMI/RFI) issues, network issues, data acquisition and data qualification algorithms, analysis of wireless data, and interpretation of the results. This paper reports on an R&D effort sponsored by the U.S. Department of Energy to demonstrate the feasibility of wireless sensors for equipment conditioning monitoring and other

2 applications in nuclear power plants. The project is aimed at development of an integrated online monitoring (OLM) system that takes signals from existing wired sensors and new wireless sensors to provide a holistic view of the health of equipment and processes as installed in nuclear power plants. INTRODUCTION Power generation utilities are striving to use wireless technologies in nuclear power plants but they are faced with a number of important challenges including infrastructural issues, security risks, reliability questions, and interference problems. Furthermore, wireless technologies are still maturing and a number of critical questions must be addressed as to how and in which areas they can best serve the nuclear industry. These questions are under investigation in a R&D project being conducted by the authors of this paper at the Analysis and Measurement Services Corporation (AMS). The project is funded by DOE in two Phases to be completed over a period of three years. The Phase I effort is completed and the Phase II project is pending. In Phase I, the feasibility of wireless sensors for equipment condition monitoring in nuclear power plants was successfully addressed. In Phase II, this R&D effort will continue for another two years to address the technical issues that must be resolved to establish the foundation for widespread use of wireless technologies in nuclear power plants. The R&D will focus not only on equipment condition monitoring, but also, and as importantly, for a variety of other applications such as equipment aging and obsolescence management, manpower savings, reduction of radiation dose to maintenance personnel, asset management, and process measurements. This paper summarizes the work that is planned for Phase II and provides a review of what was accomplished in Phase I. Figure 1 illustrates the potential applications of wireless technology in nuclear power plants. During Phase I, a survey of 20 nuclear power plants was conducted to determine the current extent of wireless use in these plants. The results are shown in Figure 2. It is clear that voice and data communication is currently the most prominent application in these plants. It is expected, however, that wireless technologies for equipment condition monitoring, process measurement, and other applications will find their way into the nuclear industry over the next five to ten years depending on how soon researchers resolve the implementation issues through R&D efforts like the one that is described in this paper. Although wireless sensors and related technologies are still evolving, through the Electric Power Research Institute (EPRI), utilities have been rather proactive in assessment of these technologies for nuclear power plants. In particular, EPRI has launched numerous efforts over the last few years to examine the potential of wireless sensors for equipment condition monitoring and other applications in both fossil and nuclear power plants. For example, in cooperation with EPRI, the Comanche Peak Nuclear Power Station in Texas has taken advantage of wireless technologies to build a communication and networking infrastructure in the plant that also incorporates wireless sensors for equipment condition monitoring and diagnostics.

3 WRLSS021-3 Dosimetry and Dose Reduction Voice and Data Communications Process Measurements Nuclear Plant Nuclear Plant Condition Monitoring Security Figure 1. Potential Wireless Technology Applications in Nuclear Power Plants WRLSS034-2 Wireless Dosimetry Voice Communications Equipment Monitoring Laptops, PDAs Camera Monitoring Heavy Equipment Operation Percentage of Wireless Use Figure 2. Results of Survey of Current Wireless Use in Nuclear Power Plants

4 PROJECT OBJECTIVES A Phase II R&D project is pending with the goal to establish the foundation for commercial implementation of wireless technologies for equipment and process condition monitoring and other applications in the current and next generation of nuclear power plants. This goal will be achieved through a hands-on R&D effort to meet the following objectives: 1. Design and development of a prototype system for acquisition, qualification, storage, and display of data from wireless sensors. 2. Testing of the prototype system using data from wireless sensors as installed in a laboratory flow loop at AMS. These tests will be aimed at verifying the operation of the prototype system and to validate its software. 3. Assessment of wireless technology security risks and development of recommendations and procedures for risk reduction. 4. Investigation of EMI/RFI to include the effects of wireless transmission on existing plant equipment, including digital systems. Conversely, investigate the potential interference issues associated with the effects of plant equipment on wireless systems. 5. Identification of target application(s) for wireless technologies in a host utility plant and implementation of the prototype system. 6. Resolution of implementation issues and development of procedures and guidelines for implementation of wireless technologies in nuclear power plants. 7. Recommendations for wireless equipment integration in the design of next generation of nuclear reactors. The project will focus on implementation issues and will not directly address questions such as battery life, power harvesting to extend battery life, modulation, encryption, bandwidth, and latency. These issues are related to development of wireless technologies as opposed to applications of wireless technologies and are under investigation by other groups including manufacturers, trade organizations, and researchers. Table 1 presents examples of common terms and issues with wireless technologies and identifies the topics that will be addressed in Phase II. Figure 3 illustrates the elements of this R&D including the effort to be conducted to commercialize the product of this work over a three-year period.

5 Table 1. Typical Wireless Technology Issues and those that are Addressed in this Project Issues Antenna Type Bandwidth Carrier Frequency Channel Access Coexistence Coverage Area Data Rate EMI/RFI Encryption Latency Modulation Network Topology Packet Path Loss Reliability Security Signal Propagation Spread Spectrum Definition or Effect The selection of antenna gain, direction, orientation, and type affects the performance of wireless transmission and reception. The maximum amount of data that can travel through communication path in a given amount of time. Frequency of the waveform used to modulate the message signal for transmission. The technique employed by the communication system to accommodate multiple users. This can include time division, frequency assignment, or code separation. Ability for a device to perform its intended function without affecting or being affected by other devices. The geographic area in which the signal strength is sufficient to allow for a wireless signal to be correctly received and decoded. The amount of data transferred per second, usually expressed in bits/second. The effect of radiated emissions of the plant equipment and wireless system on each other s performance. The conversion of data into a form that cannot easily be understood by unauthorized users. The delay associated with the transmission of a wireless signal from a transmitter to a receiver. The process of incorporating information onto an RF carrier signal for transmission. Defines how wireless devices are linked to each other and the routing of data traffic. The grouping of bits composed of data and overhead information which is combined and transmitted. The reduction in power density associated with free space propagation. Ability of a system to perform a required function under stated conditions for a specified period of time The protection of system resources from accidental or malicious access, use, modification, destruction, or disclosure. Deals with how a signal travels through the air and the physical characteristics of the environment which could affect transmission such as reflection, diffraction, and scattering. Technique used to avoid interference and/or detection. Addressed in Project Reasons for Addressing the Issue in this Project Implementation Issue The selection of the antenna impacts the orientation, placement, and coverage area for a transmitter or receiver. Implementation Issue Different operating frequencies have a different EMI/RFI impact on existing plant equipment. Development Issue The wireless devices must be able to operate in the presence of other wireless devices and not affect their performance. ImplementationIssue The coverage area must be determined in order to maintain a reliable communication link. Implementation Issue The wireless system must have no negative impact on existing plant equipment. Development Issue Affects the coverage area and placement of wireless transmitters and receivers. WRLSS048-5 Implementation Issue Reliability is an important consideration in nuclear power plantapplications. Development Issue Security must be addressed for a wireless system to be deployed at a nuclear facility. Implementation Issue Due to the harsh environment in a nuclear facility, the signal propagation must be taken into account.

6 WRLSS047-2 Year 1 Activities (Preparation Work) Year 2 Activities (Field Implementation) Year 3 Activities (Commercialization) Develop Prototype Data Acquisition, Qualification, and Storage System Prepare Procedure for In- Plant Implementation of Phase II Prototype Develop Commercial System Validate the Prototype System using Laboratory Data Perform EMI/RFI Mapping of Selected Nuclear Plant Develop and Distribute Marketing and Advertising Material Select a Nuclear Power Plant to Host the Phase II Implementation Install Wireless Equipment in the Nuclear Plant Make Presentations to Nuclear Industry Select Specific Nuclear Power Plant Application(s) for Phase II Implementation Acquire and Qualify Data Participate in Conferences and Exhibitions to Showcase the Phase II Product Research Cyber Security Risks and Regulatory Concerns Demonstrate the Operation of Phase II Prototype Sell the Product of Phase II Figure 3. Phase II Objectives and Milestones

7 RESULTS OF PHASE I EFFORT The Phase I effort had six objectives; all of which were successfully met during the time allotted for the project starting on June 28, 2007 and ending on March 28, 2008 (nine months). The key accomplishments of the Phase I project are listed in Table 2 and examples of some of the more important achievements of the Phase I work are summarized below. Evaluation and Selection of Wireless Sensors Eleven manufacturers of wireless sensors and transmitters were evaluated during Phase I of which eight have products that can be used for the R&D work proposed in this paper. The results of this evaluation are in Table 3. Three of these manufacturers (Honeywell, Emerson, and Techkor) loaned wireless sensors to AMS for the Phase I project. The three manufacturers that were evaluated but are not listed in Table 3 are Siemens, Telesensors, and Azima. Laboratory Research With Wireless Sensors An existing test loop at AMS was used to take data from wireless sensors, compare them with data from wired sensors, and analyze them to demonstrate the feasibility of wireless sensors for equipment condition monitoring and other applications in nuclear power plants. Figure 4 shows traces of raw data from these tests. Integration of Wireless with Wired Sensors A prototype data acquisition system to acquire both wireless and wired sensor data was developed and tested in Phase I. With this system, wired and wireless sensor data were sampled simultaneously and stored in a common database (historian) for subsequent analysis. Equipment Fault Detection Using Wireless Sensors Artificial faults were introduced in the equipment and/or the processes (simulated by the test loop) to determine if the faults can be detected using data from wireless sensors. The purpose of this experiment was to validate the data collection and data analysis algorithms and software packages used in Phase I. This effort was very successful. Nuclear Industry Interviews and Surveys Interviews and surveys were conducted with technical representatives in nuclear power plants to identify the areas of greatest interest in wireless technologies and potential roadblocks to implementation of these technologies in nuclear power plants such as reliability problems, security concerns, and regulatory issues.

8 Table 2. Summary of Work Completed to Satisfy Each Objective of the Phase I Project Technical Objectives of Phase I Project Phase I Accomplishments 1. Select and acquire wireless sensors for lab testing. Wireless sensors from eleven manufacturers were evaluated. Six of these manufacturers visited AMS during the Phase I project and discussed their products. Three of the manufacturers (Emerson, Honeywell and Techkor) loaned wireless sensor systems for the laboratory tests in Phase I. 2. Develop a matrix of industrial equipment versus condition monitoring parameters. The work toward this objective concluded that temperature, vibration, pressure, humidity, and radiation dose are among the most important parameters for nuclear power plant applications. This work included an evaluation of nuclear power plant equipment and processes that can be monitored with wireless sensors and the faults that can be detected using wireless sensor data. 3. Identify filtering, qualification, and analysis algorithms and software packages for handling wireless sensor data. New and existing algorithms and software packages at AMS were used for this objective and were found to be adequate for handling of wireless sensor data for the Phase I feasibility study. The largest issue is qualifying and synchronizing the wireless data which required the development of new algorithms. 4. Perform laboratory experiments to evaluate the algorithms and software packages. Significant progress was made during Phase I toward this objective. Data were collected in two AMS test loops using both wired and wireless sensors under the same conditions. Then, artificial faults were introduced in the equipment as installed in the AMS test loops and wireless data were collected and analyzed to demonstrate that the faults can be detected and characterized using data from wireless sensors. 5. Create a design for prototype system for equipment health and condition monitoring. A system was designed using wireless sensors which also allows for the incorporation of existing wired sensors to provide a holistic assessment of the health of a nuclear power plant and its equipment and processes. 6. Identify a host utility for in-plant testing of the product of this project in Phase II. Many utilities came forward during Phase I as volunteers to participate in the Phase II project. Four of these provided support letters for the Phase II project.

9 Table 3. Manufacturers and Product Specifications for Wireless Equipment Evaluated in Phase I Item Manufacturer Operating Frequency Fastest Sampling Frequency Optimum Battery Life Range Network Topology Security 1 Accutech 900 MHz 1 sec 20 yrs 3000 ft LOS 1000 ft NLOS STAR Proprietary 2 Cirronet 2.4 GHz 10 Hz 5 yrs 4000 ft LOS 300 ft NLOS MESH 128 bit AES 3 Honeywell 2.4 GHz 1 sec 10 yrs 1000 ft LOS MESH 4 Oceana 2.4 GHz 48 khz AC 300 ft LOS Piconet WPA2,AES FIPS Bluetooth RLW 2.4 GHz 192 khz AC 300 ft MESH b 6 Rosemount Emerson 900 MHz or 2.4 GHz 15 sec 10 yrs 650 ft MESH AES FIPS Sensicast 900 MHz or 2.4 GHz *1 min default 2 yrs 700 ft LOS 230 ft NLOS MESH Proprietary 8 Techkor 900 MHz 40 khz 1 yr 250 ftlos STARw/ repeaters Encrypted

10 Differential Pressure 1.2 Differential Pressure (psi) Pump Vibration :36 10:48 12:00 13:12 14:24 15:36 16:48 18: Time (hours) Temperature Near Pump Vibration (rms) Temperature (deg F) :36 10:48 12:00 13:12 14:24 15:36 16:48 18:00 Time (hours) :36 10:48 12:00 13:12 14:24 15:36 16:48 18:00 Time (hours) 1.00E E E 01 Wireless (Rosemount) 1.00E E E E 05 Wired (Wilcoxon) 1.00E E E E E E+04 Figure 4. Raw Data Traces from Laboratory Experiments Conducted in Phase I

11 Table 4 summarizes the results of these interviews in terms of potential wireless applications in nuclear power plants. Review of Related Research Related work by other researchers regarding wireless technologies in the nuclear industry were reviewed. This included the work of EPRI, Oak Ridge National Laboratory (ORNL), the U.S. Nuclear Regulatory Commission (NRC), Pacific Northwest National Laboratory (PNNL), Idaho National Laboratory (INL), and others. The purpose of this review was to establish the state-of-the-art in wireless technologies for nuclear power plants. This review concluded that wireless technologies are currently used to some extent for voice and data communications in nuclear power plants but their use for other applications are very limited due to infrastructural issues and security concerns. That is, most nuclear power plants do not have a wireless backbone to build upon and include wireless sensors for the variety of applications that exist in nuclear power plants. It should be mentioned that work in wireless application areas for nuclear power plants is also proceeding at international research organizations, laboratories, and universities. In Phase I, however, only the work of representative U.S. organizations was reviewed. CONCLUSIONS A Phase I R&D project sponsored by DOE has been completed to establish the feasibility of wireless technologies for equipment and process condition monitoring in nuclear power plants. The next step is to begin a Phase II effort that is due to run for two years to develop and implement a prototype system to use wireless technologies for a variety of applications in nuclear power plants. This paper presented the key results of the Phase I project and the plan for Phase II. REFERENCES 1. Hashemian, H.M., Sensor Performance and Reliability." Book published by ISA The Instrumentation, Systems, and Automation Society, Hashemian, H.M, Maintenance of Process Instrumentation in Nuclear Power Plants. Book published by Springer-Verlag, 2006.

12 Table 4. Summary of Potential Nuclear Power Plant Applications of Wireless Technologies Identified in Phase I Nuclear Plant System Heat Exchangers Secondary Side Valves Inlet Water Intake Rotating Equipment (pumps, valves, motors, compressors, fans) Diesel Generators Spent Fuel Dry Cask Storage Weather Station Wireless Measurement(s) Temperature Position Indication Level, Temperature, Flow Temperature, Vibration, Motor Current Temperature, Level, Vibration, Motor Current Temperature, Radiation Temperature, Wind Velocity, Pressure, Humidity, etc. Application Monitor ambient temperature to take into account the effects of such factors as seasonal changes in weather. Replace periodic, labor-intensive valve indication readings with continuously monitored wireless measurements. Monitor factors that affect performance such as changes in level, seasonal temperature variations, and intake flow. Monitor temperatures, vibration signatures, and load fluctuations to assess condition and improve performance. Augment existing sensor readings to provide redundancy and comprehensive performance assessment. Eliminate need for underground cabling and conduit by monitoring temperature and radiation with wireless sensors. Improve monitoring by replacing failure-prone equipment and cabling with wireless measurements.