Multi-Parameter Sensor for Next-Generation Nuclear Reactors

The next generation of nuclear reactors will offer significant improvements over the existing fleet of light water reactors, namely inherent safety features, greater siting flexibility, lower operations and maintenance costs, load-following capabilities, greater fuel utilization, and proliferation resistance. In addition, these new reactors offer the ability to support applications such as hydrogen production, water desalination, and industrial heat generation among others. Next-generation nuclear reactors under development in the United States and elsewhere comprise a wide range of designs to realize these benefits including molten salt reactors, liquid metal cooled reactors, gas cooled reactors, and heat pipe reactors. These reactor technologies range from transportable micro-modular systems to large-scale power plant facilities. Despite their differences, many prominent next-generation nuclear reactors share key attributes including elevated temperatures, corrosive coolants, high radiation levels, harsh process and/or environmental conditions, extended refueling cycles, and limited space to accommodate redundant sensors; all of which challenge the performance of conventional nuclear grade safety related instrumentation like resistance temperature detectors, thermocouples, and pressure transmitters which have not been qualified for service in next-generation reactors. Existing nuclear grade sensors cannot survive the long-term effects of the harsh process conditions and environmental stressors expected in next-generation reactors without frequent and costly replacements or untimely maintenance due to calibration drift or premature degradation. As a result, to meet the needs of the next generation of nuclear reactors, the authors of this paper are developing a high-temperature and irradiation-resistant sensor capable of providing accurate and reliable temperature, level, and/or flow measurements.