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Introduction
Small Modular Reactors (SMRs) are at the forefront of new reactor development and implementation in the United States and a few are slated for operation in about a decade. For example, the Idaho National Laboratory (INL) area has been mentioned as the site of the first prototype SMR to be built in the U.S. and begin operation well before 2030. The Utah Associated Power System's Carbon Free Power Project is behind the launch of this plant and has selected the NuScale reactor which is a natural circulation type integral pressurized water reactor.
SMRs are different than conventional nuclear power plants and therefore need different measurement methods, new sensors, and alternative sensor installation mechanisms. Examples of differences between SMRs and conventional reactors which can affect the instrumentation and control (I&C) sensors are: 1) the vessel's internal structure and compact geometry which limit the size, number, and placement of the sensors; 2) operating regimes which present new challenges especially in measurement of primary coolant flow and reactor vessel level; and 3) environmental conditions around I&C sensors including the potential for placing some of the sensors underwater. Furthermore, I&C capabilities must be enhanced for SMRs to enable these plants to operate with reduced number of operation and maintenance (O&M) personnel and facilitate plant availability for an operating cycle that could be much longer than the current fleet of reactors. Figure 1 provides examples of some of the unique SMR I&C challenges.
With a grant from U.S. Department of Energy, AMS is conducting a research and development (R&D) project that is aimed at development of new sensors, adaptation of existing sensors, evaluation of wireless sensors and related technologies, assessment of emerging sensors, and development of sensor qualification standards for nuclear safetyrelated applications in SMRs. A few of these activities are presented in this article.
Background
As in conventional nuclear power plants, SMRs are expected to require numerous sensors for the control of the plant and monitoring of its safety. This requirement competes with the limited space that is available in current SMR designs; especially if the existing generation of sensors is to be used. Furthermore, the existing generation of sensors is not designed for some of the unique requirements of SMRs. For...