O ak Ridge National Laboratory (ORNL) is investigating embedded instrumentation and controls (I&C) technology for next generation nuclear power generation applications. Embedded systems encompass a wide range of configurations and technologies; we define embedding in this instance as the integration of the sensors and the control system design into the component design using a systems engineering process. Embedded I&C systems are often an essential part of developing new capabilities, improving reliability, enhancing performance, and reducing operational costs. The next generation reactor technologies with passive safety features will benefit from the development and application of new I&C technologies. Some of these new designs raise extreme environmental challenges such as high temperatures (over 1,400 °C) and material compatibility (e.g., molten salts). The desired reliability and functionality requires measurements in these extreme conditions including high radiation environments which previously were not monitored in real time. The U.S. Department of Energy, Nuclear Energy Advanced Sensors Initiative (ASI) is a technology cross-cutting initiative under the Nuclear Energy Enabling Technologies (NEET) program that currently has several projects investigating I&C technologies that will make new reactor designs more efficient and practical. The ASI project described in this paper has the specific goal of investigating embedded I&C with the following objectives:◗ Explore and quantify the potential gains from embedded I&C -improved component reliability, increased performance, and reduced cost. ◗ Identify practical control, sensing, and measurement techniques for the extreme environments found in hightemperature reactors. ◗ Design and fabricate a functional prototype hightemperature pump for molten salts -represents target demonstration of improved performance, reliability, and widespread usage. There are many engineering challenges in the design of a high-temperature liquid salt pump. The pump and motor are in direct contact with molten fluoride salt at 700 °C (1,292 °F) as part of a reactor loop. The motor-pump combination during normal operation would be glowing cherry red (Fig. 1). This environment challenges every facet of the design including seals, wiring, magnetic materials, and sensors.In this paper, we will focus our discussion on the challenges of sensor design in extreme environments and specifically the sensor design for a high-temperature fluoride salt pump. The high temperature pump, while not the goal of the project, will be used to demonstrate the performance improvements that embedded I&C can bring to nuclear power plant components and as a test-bed to assist in the development and validation of I&C techniques for extreme environments.
Sensors in Extreme EnvironmentsMany extreme environments require highly specialized and sensitive engineering tactics. Enterprises in aerospace, energy, deep sea, subsea, deep mining, and transportation present challenges unassociated with standard circumstances, a...