Assessment of Nuclear Sensors and Instrumentation Maturity in Advanced Nuclear Reactors

Abstract

In the last decade, 97% of the worldwide commercial nuclear reactors connected to the grid were Light Water Reactors (LWRs). LWRs are expected to stay the dominant type of nuclear reactors for the next few decades. Reliable and redundant safety systems are required in nuclear reactors to ensure safe operation and shutdown in abnormal conditions. These safety systems are actuated by the signals obtained from several sensors and instrumentation in and out of the reactor core. Research and Development (R&D) in advanced sensors and instrumentation has gained extra attention, particularly following the accident at the Three Mile Island Unit-2 (TMI-2). In LWRs, these sensors and instrumentation have shown a high level of maturity with long operating experience. Ensuring the compatibility of these sensors and instrumentation with advanced nuclear reactors (Generation IV) is necessary, particularly with the expected expansion of the nuclear industry in the next few decades. Nuclear Sensor and instrumentation technologies used in the current generation of LWRs were investigated. The compatibility of these technologies with advanced reactors was assessed by comparing the advanced reactors' environments with those of the currently operating reactors. In addition to that, the needed R&D for such technologies was highlighted. In comparison with the LWRs environment, it was shown that advanced reactor environments are expected to experience elevated temperatures, a fast neutron spectrum, and a harsh corrosion environment. It was demonstrated that R&D is required mainly for fixed in-core nuclear sensors and instrumentation, while it is not a priority for ex-core nuclear sensors and instrumentation.In LWRs, sensors and instrumentation passed a long way of R&D until they reached a high level of maturity. However, the advanced reactor designs pose new challenges to these sensors and instrumentation, mainly due to the differences in the operating environments of the reactors. Some sensors and instrumentation, particularly in-core sensors and instrumentation, will operate in conditions significantly different from those in the current generation of nuclear reactors. High-temperature and corrosive environments can impose significant challenges to the design of sensors and instrumentation. In addition to that, these operating conditions could also impact sensors and instrumentations' reliability and accuracy. As a result of these factors, R&D programs are emerging, intending to commercially obtain sensors and instrumentation specifically designed for these types of reactors.