Currently there is a significant need for harsh environment sensors, sensor systems, and sensor packaging materials/components that can provide monitoring and prognostic capabilities for operations inside advanced nuclear power plants. These sensors must be tolerant to high radiation/neutron fluences and high operating temperatures (up to 700 C), while also being able to operate wirelessly, require little/no power, and possess small form factors. To meet this need, the objectives of the proposed work are to perform in-situ studies on the effects of intense gamma and neutron irradiation on langasite (LGS)-based surface acoustic wave resonator (SAWR) sensor devices. LGS has been shown to withstand temperatures up to its melting point above 1400 C while still retaining its piezoelectric properties, and has been extensively studied by UMaine as a SAWR temperature sensor device in several high-temperature and harsh-environment applications, including turbine engines and power plant boilers. To extend its utility and potential use in advanced nuclear reactor power plants, LGS SAWR sensors will be fabricated and fully instrumented at UMaine, and tested at Ohio State University (OSU) Nuclear Research Laboratory and/or other Nuclear Science User Facilities (NSUF) partner institutions to monitor the effects of gamma and neutron irradiation on sensor performance over time and temperature. Specifically, the proposed studies will involve in-situ vector network analyzer (VNA) RF electronic monitoring and characterization of the LGS SAWR sensors frequency response, thus measuring potential changes in signal amplitude, bandwidth/Q-factor, and/or resonant frequency as a result of irradiation exposure. Both LGS sensors and VNA instrumentation will be provided and installed by UMaine personnel at the OSU/NSUF partner institution to conduct the irradiation studies over a test period of approximately 1-2 weeks. The anticipated scientific outcomes will include the filling of knowledge gaps regarding LGS SAWR sensor functionality and overall performance characteristics when exposed to high levels of gamma/neutron irradiation, and will significantly advance the state-of-knowledge and the technical maturity of LGS-based SAWR sensors for applications within existing and future advanced reactor fleets. In particular, SAWR sensors designed, fabricated, and packaged by the UMaine team have already undergone test and evaluation within a coal power plant, municipal waste power plant, aerothermal generator facility, and small / large scale turbine engines, and the proposed work will extend the applicability of these SAWR sensors into nuclear environments.

The work proposed in this application will advance the mission of the Office of Nuclear Energy by developing advanced sensors and sensor systems that are capable of long-term, stable operation in extreme environments found in many advanced nuclear reactor facilities and concepts, thus contributing to the long-term viability and competitiveness of existing and future advanced reactor fleets. Specifically, the proposed research supports and advances several DOE-NE topics related to advanced sensor development and sensor testing found within the Advanced Sensors and Instrumentation (ASI) Program; and in the FY 2024 CINR FOA topic areas: Topic Area 9 – Measuring, Monitoring, and Controls; and NSUF 1.2 and 2.2 – Testing of Advanced Materials for Sensors.



Currently there is a significant need for harsh environment sensors and sensor systems that can provide monitoring and prognostic capabilities for operations inside advanced nuclear power plants. These sensors must be tolerant to high radiation/neutron fluences and high operating temperatures (up to 700 C), while also being able to operate wirelessly, require little/no power, and possess small form factors. To meet this need, the objectives of the proposed work are to perform in-situ studies on the effects of intense gamma and neutron irradiation on langasite (LGS)-based surface acoustic wave resonator (SAWR) sensor devices. The proposed irradiation exposure studies of LGS SAWRs are to be conducted at an NSUF partner institution facilities, and will involve in-situ RF electronic measurements of the SAWR device responses as a function of gamma/neutron fluence levels, exposure time and temperature.

The proposed work will leverage over two decades of experience in microwave acoustic sensor research at UMaine. Specifically, in a recently funded project through DOE NETL, the UMaine research team fabricated, installed and tested 18 wireless LGS SAWR sensors in a coal fired power plant (Longview Power, Maidsville, WV), where these sensors survived harsh conditions and successfully enabled remote monitoring of temperatures inside a high temperature reheater boiler (approximately 500 C) wirelessly and continuously for 3 years. The proposed work will investigate the usage of this technology and fill knowledge gaps regarding the functionality and overall performance characteristics of high temperature harsh environment LGS-based SAWR sensors when exposed to high levels of gamma/neutron irradiation commonly found within advanced nuclear power plants.

The proposed work will also synergistically build upon an ongoing project at UMaine that is funded through the Nuclear Regulatory Commission (NRC) to develop a LGS SAWR vibration monitoring sensor that is capable of withstanding extreme temperatures and gamma radiation environments found within advanced molten salt reactors. For this project, the UMaine team is currently utilizing a Nuclear Chicago NH-3 neutron howitzer with Pu-Be neutron source, along with Cs137 gamma sources, that are available within UMaine’s Environmental Radiation Lab to perform preliminary in-situ irradiation studies on LGS SAWR sensors and sensor systems. Access to more intense irradiation sources found within NSUF partner institution facilities will expand upon this ongoing project by allowing for additional in-situ studies at significantly higher fluence levels than what are available at UMaine facilities.