36i: Fiber-Optic Multifunctional Sensor for Crack Monitoring in Harsh Environments

Statement of the problem or situation that is being addressed:
Nuclear power is a key component in enabling our nation to develop and deploy clean, affordable, domestic energy sources. One of the main challenges in expanding the use of nuclear power is developing technologies which improve the reliability, sustain the safety, and extend the life of current reactors. Safe and reliable reactor operation requires knowledge of how new advanced materials will behave and age in the environment. Novel sensors capable of withstanding harsh environments are vital measurement tools for building material performance databases of novel advanced materials, enabling key information such as material displacement at high temperatures. The environments of interest for Gen IV reactors include high radiation, very-high-temperature, and chemically harsh conditions. The proposed sensor will provide material scientists an innovative advanced sensor able to withstand the extreme conditions of Gen IV reactors.
General statement of how this problem is being addressed:
Luna is proposing to develop a compact fiber-optic multifunctional sensor that will monitor material crack growth in the harsh environments of Gen IV nuclear reactors. The novelty of this sensor lies within its capability to measure temperature and displacement simultaneously as well as being able to operate in electrically conductive environments such as liquid metal where electronic sensors are not viable. The core technology behind the sensor lies in Luna’s Fabry-Perot Interferometer (FPI) based displacement gauge and the combination of this FPI sensor with inline femtosecond laser-induced Fiber Bragg Grating sensors, both of which are radiation tolerant.
Phase I activity:
During the Phase I effort, Luna will investigate the feasibility of the approach through experimental validation to demonstrate the sensor’s ability to measure temperature, and displacement simultaneously in a series of notched sample stress corrosion cracking (SCC) experiments. The sensors will be integrated into samples for Virginia Tech’s SCC tester. Data will be collected and analyzed at room temperature and at temperatures up to 320?, with the sample being submerged in water and inert gas. In addition, the sensor will be immersed in molten metal to observe any damages to the sensor. Luna will also prepare plans for commercialization and Phase II testing. During Phase II, the team will target sensor operation in molten metal, molten salt, and at very-high-temperatures (750?+).
Commercial applications and other benefits
Due to the uniquely small form factor and ability to operate in harsh environments, Luna sees great opportunity in research markets such as nuclear reactors, oil and gas refinery operations, and solar power concentrators amongst other energy-based markets. In the nuclear market, distributed temperature and crack formation sensing in the reactor containment areas will increase efficiency and safety. Since the radiation tolerant developed sensors will also be high-temperature capable, they will also find application in rocket engine monitoring, rocket engine development, gas and coal power plants, solar salt power plants, and in gas turbine health monitoring.