The primary challenges associated with Very High Temperature Reactors (VHTR) stem from their extremely high operating temperatures, especially during accident conditions which way has necessitated new material systems to be developed for most of the core construction, including fuel. There currently exists no method to characterize the mechanical properties of advanced refractory materials used in emerging Gen-IV reactors. Lambda Instruments, Inc. is developing extremely high-temperature, radiation-hardened fiber optic strain sensors based on our unique sapphire waveguide technology. Sapphire is an inherently high-temperature material and has been shown to retain excellent transmission properties in moderate radiation and extreme high-temperature environments. All of the primary objectives of the Phase I were achieved with great success. Sapphire fibers were shown to survive in both high temperature (1600C) and moderate radiation (3.3x1017n/cm2, & gt;1MeV) environments. Strain sensor fabrication methods for high-temperature operation were designed and implemented. These initial fabrication methods demonstrated success at high temperatures up to 1600C. Additional fabrication methods for improved sensor ruggedization and survivability were also conceived and will be implemented during the Phase II project. The primary objectives for Phase II include: 1) Improving strain sensor ruggedization, 2) Design and build optimized readout system, 3) Demonstrate extended survivability in high-temperature and high-radiation environments, 4) Demonstrate operation in high-radiation environment, and 5) Develop commercialization and transition to manufacturing strategy. Commercial Applications and Other
Benefits: The primary commercial applications include emerging Gen-IV VHTR plants. The primary public benefit will be improving the safety and performance of emerging high temperature gas-cooled reactors. With growing international competition in nuclear power, the U.S. is at risk of losing our preeminent position in new reactor development. The development and international acceptance of these advanced reactors could result in a significant export for the U.S.. Key to that development, however, is safety, reliability, performance and cost. The proposed sensor development in Phase II supports all of these thrusts.
