Instrumental and Control Systems in Nuclear Power Plants - Research Paper Example

Instrumentation and Control Systems used in Nuclear Plants Introduction Nuclear power plants are controlled, monitored, protected and managed by instrumentation and control systems. The I&C control systems have served their purpose of controlling and monitoring the nuclear power facility over the past years with considerable satisfaction. With the world of technology and processing systems constantly evolving, the new developments have been implemented in almost all fields and are slowly taking over nuclear power facilities with digitalized monitoring and control systems to meet a variety of challenges such as environmental degradation mechanical failure, aging, and obsolescence. The new technologies are slowly overcoming the complications and uncertainty that are inherent to a new technology and the problems encountered by applications of digital I&C in nuclear facilities. Without the controlling and monitoring systems, there would not be a feedback that would ensure that the system is running safely, which is the reason behind the emergence of these technologies. Instrumentation and control (I&C) systems affect all areas of plant operation and can profoundly impact plant reliability, efficiency, and operations and maintenance (O&M) costs. (epri.com). This paper discusses the developments in the instrumentation and control systems used in nuclear power plants, specifically nuclear monitoring instrumentation, process monitoring instrumentation and radiation monitoring instrumentation. Recent developments in nuclear instrumentation technology and its utilization The recent developments in the technologies are now facing challenges of producing reliable, low emission power. As a result a range of technologies have been introduced and have been utilized in nuclear power facilities. The traditional analog systems are based on current, voltage and pneumatic systems, while the present generation I&C systems are computer-based equipment and are constantly becoming more automated. (White, 1994). Some of them include neutron monitors, source range monitors, gamma and neutron traversing in-core probes, mechanical drive equipment, environment radiation monitors, local power range monitors, in-core detectors and ex-core detectors. (gepower.com). Apart from these specific monitoring systems, the technologies that have risen in the past ten years that have proved to be useful. Spectroscopy gives detailed information which would ensure that the sample and the quality of the results will be much better than other methods, making the assessment technique preferable over others. Ge detectors have more definitive nuclide identification, more accurate nuclide quantification, lower detection limits, a wider dynamic range, better stability, and much higher overall confidence in the results. (Bronson, 1996). All processes are managed by a computerized and digital system which would make it possible to use extremely sophisticated software that would enable automatic and reliable operations to be carried out, followed by the analysis of the data, recording and interpreting of results and appropriate implementation of the required action. In addition to the many benefits, it is an added advantage that the performance of the system may be predicted. With such technology taking the lead and supporting services for instrumentation, the nuclear power facilities are greatly developing, moving toward a safer and more sustainable power generation cycle. The technologies that have been developed for nuclear power plants have been utilized for a range of purposes in monitoring and controlling. It has helped in gaining better access to information on the processes that are happening inside the reactor by providing a detailed analysis of the processes as seen from the inside of the reactors. The technology of in-core probes has shown great advancements, enabling them to be used in monitoring the processes of the reactor in detail, leading to better accuracy in the processes. The applications that the technologies have found in the nuclear facility are numerous, the most important application being the monitoring of the nuclear reactor and radiation with accuracy. The technological characteristics of the digital monitoring systems are similar to those of monitoring systems for other purposes and have input and output range, response time and accuracy. (National Research Council). These aspects, however, have been structured specifically for the requirements of the nuclear facility, providing for maximum utilization of the advanced digital monitoring and controlling systems. In consideration of the high risks involved in case of failure, the I&C systems are required to be very accurate and should be thoroughly reliable even in reducing risks of low probability events. These technologies have found their rightful place in an industry that demands as much accuracy and perfection in the processes. Undoubtedly, the developments have been utilized by the facilities effectively for a wide range of purposes. Monitoring systems for nuclear power plants The aging technology of analog monitoring systems is now being replaced by advanced, hi-tech, more accurate digital monitoring instrumentation. The advent of computer-based monitoring and display systems has provided opportunities for advancements which will improve the ability of the operators to understand the plant status, and therefore, improve the operator's ability to make the best decisions during the plant transients which might otherwise become accidents. (White, 1994). The most recent and advanced technology in regard to monitoring systems is perhaps the real time artificially intelligent monitoring system, also known as AIMS. These systems are to assist nuclear facility operators. The kernel of AIMS is an object-oriented knowledge-base system, in which acquired and calculated variables, as well as their interdependencies, are mapped into a hierarchical objects network where the rules and real-time constraints are implicit in objects operators and network topology. (Schirru and Periera, 2004). Monitoring systems are integrated into various parts of the nuclear power generation facility, from neutron monitors to source range monitors to environmental radiation monitors. Software quality assurance is seen to be an important aspect of installing a monitoring system, so as to check and monitor process compliance, ensuring that the monitoring systems will work efficiently and safely. Process monitoring instrumentation Process monitoring instrumentation plays a major role in monitoring and maintaining safe and satisfactory generation of nuclear power generation. Some of the advanced process monitoring systems that are used in nuclear power plants include neutron flux monitoring systems, reactor control and alarm subsystems, magnet power supply and scram logic assembly (reactor protection system), and rod control system. (thermo.com). The Neutron Flux Monitoring System is a life fission chamber detector for Source, Intermediate, Power Range and Post-Accident Monitoring applications. (thermo.com). Advanced core processing monitoring designs and instrumentation are now used in nuclear power generation facilities. The process signals of the plant may be measured and analyzed using the digital data acquisition system. The measured time signals are influenced by core process transients, global and local process fluctuations and by signal line transfer functions. (Pohlus, 2003). New methods of advanced time series are used to separate the process effects of different parts in a multiple signal matrix. The separation of different process influences can improve significantly the information about the process condition in the reactor core. (Pohlus, 2003). These technological advancements have certainly brought improvements in the instrumentation and monitoring systems of the nuclear power generation facilities. Radiation monitoring instrumentation There are hundred of workers in each nuclear power plant and it becomes increasingly important to monitor the radiation levels which could cause potential harm to the body and the environment equally. The use of radiation monitoring systems would enable nuclear power generation facilities to have a watch on the amount of radiation that is being released. The amount of radiation that is liberated must be constantly monitored to maintain safe levels and would help in recognizing an emergency of radiation leak. Every nuclear power plant is continuously monitored by a bevy of dosimeters that are placed at different distances and on different sides of the plant. These dosimeters measure radiation dose from the plant or any radioactivity that is released by the plant. (hps.org). Automatic systems for radiation monitoring are now widely used in power plants. The use of portable and permanently installed radiation monitoring instrumentation has improved and provides analysis of the radiation and air concentration with accurate results and details. The determination of activity concentration in the air may be based on continuously monitoring stationary or portable measuring instruments or on the analysis of separately collected samples at the laboratory. (finlex.fi). Conclusion The new concepts and technologies that have been introduced into the nuclear sector have brought significant improvements, bringing a lot of changes in the operational and functional aspects of a nuclear power plant. The new concepts, instrumentation and monitoring systems that have been discussed in this paper have satisfactorily proved their efficiency in working conditions of nuclear plants, while also considering and placing importance on the environmental damage that the plants can cause. The process monitoring systems, as discussed earlier, are very advanced in giving real time results and analysis of the ongoing operation, supported by in-core probes and reactor monitoring systems. The gamma rays, neutron activity and reactor activity are all automatically analyzed, monitored and managed. Further, advancements in technology allow for automated decision making and implementation of appropriate measures for events resultant from the process. The new concepts that have been introduced in the nuclear power plants have been reviewed and studied, giving an insight into the current advanced instrumentation and control systems used in nuclear power plants. Reference Bronson, F.L. (1996). Nuclear Instrumentation Tools For Lower Cost And Higher Reliability Decommissioning Of Buildings And Grounds. Retrieved April 29, 2010 from http://www.canberra.com/literature/1025.asp epri.com. instrumentation and Control. Retrieved April 29, 2010 from http://my.epri.com/portal/server.pt?open=512&objID=242&&PageID=371&mode= 2&in_hi_userid=2&cached=true finlex.fi. Radiation monitoring system and equipment of a power plant. Retrieved April 29, 2010 from http://www.finlex.fi/data/normit/26218-YVL7-11e.pdf gepower.com. Reactor instrumentation for the new era of nuclear power. Retrieved April 29, 2010 from http://www.gepower.com/prod_serv/products/oc/en/reuter_stokes/downloads/rea ctor_instru.pdf hps.org. Instrumentation and measurement. Retrieved April 29, 2010 from http://www.hps.org/publicinformation/ate/q1069.html National Research Council. (U.S). (1997). Digital instrumentation and control systems in nuclear power plants. National Academy Press. Retrieved April 29, 2010 Pohlus, J. (2003). Application of advanced core processing monitoring procedures in German power reactors. Retrieved April 29, 2010 from http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V3X-48WF871- 4&_user=10&_coverDate=12%2F31%2F2003&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1315372386&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=76a79f9c17b99f55e4f7e46ae958dad2 Schirru, R. and Periera,C . (2004). A Real-Time Artificially Intelligent Monitoring System for Nuclear Power Plants Operators Support. Retrieved April 29, 2010 from http://portal.acm.org/citation.cfm?id=973605&CFID=88316786&CFTOKEN=3538 6176 thermo.com. Retrieved April 29, 2010 from http://www.thermo.com/com/cda/landingpage/0,10255,607,00.html White, J.D. (1994). Comparative assessments of nuclear instrumentation and controls in the United States, Canada, Japan, Western Europe and the former Soviet Union. Retrieved April 29, 2010 from http://www.wtec.org/loyola/ar93_94/canic.htm Read More