SUMMARYNew and enhanced nuclear fuels are a key enabler for new and improved reactor technologies. For example, the goals of the next generation nuclear plant (NGNP) will not be met without irradiations successfully demonstrating the safety and reliability of new fuels. Likewise, fuel reliability has become paramount in ensuring the competitiveness of nuclear power plants. Recently, the Office of Nuclear Energy in the Department of Energy (DOE-NE) launched a new direction in fuel research and development that emphasizes an approach relying on first principle models to develop optimized fuel designs that offer significant improvements over current fuels. To facilitate this approach, high fidelity, real-time, data are essential for characterizing the performance of new fuels during irradiation testing. A three-year strategic research program has been initiated for developing the required test vehicles with sensors of unprecedented accuracy and resolution for obtaining the data needed to characterize three-dimensional changes in fuel microstructure during irradiation testing. When implemented, this strategy will yield test capsule designs that are instrumented with new sensor technologies for irradiations at facilities primarily relied upon by the Fuel Cycle Research and Development (FCR&D) program, the Advanced Test Reactor (ATR) and the High Flux Isotope Reactor (HFIR). Prior laboratory testing, and as needed, irradiation testing of sensors in these capsules will have been completed to give sufficient confidence that the irradiation tests will yield the required data.From the onset of this instrumentation development effort, it was recognized that obtaining these sensors must draw upon the expertise of a wide-range of organizations not currently supporting nuclear fuels research. Hence, a draft version of this document was developed to provide necessary background information related to fuel irradiation testing, desired parameters for detection, and an overview of currently available in-pile instrumentation. Then, a workshop was held in which U.S. and foreign experts from fuels, irradiation, and instrumentation fields participated. Prior to this workshop, copies of a draft version of this document were distributed to participants to stimulate expert interactions at this meeting. During the workshop, candidate sensor technologies identified in this document were discussed and ranked by the experts using agreed upon criteria. The final version of this document describes the consensus reached during the workshop with respect to recommendations for the path forward for accomplishing the goals of this research program.Based on the activities completed to develop this strategic plan, it is recommended that the FCR&D instrumentation development program be initiated as a three year program that includes the following three tasks:• Ultrasonics-Based Evaluations -In this task, laboratory evaluations and necessary irradiations will be completed to demonstrate the viability of this technology for in-pile applications. Specif...
This paper reports the testing results of radiation resistant fiber Bragg grating (FBG) in random air-line (RAL) fibers in comparison with FBGs in other radiation-hardened fibers. FBGs in RAL fibers were fabricated by 80 fs ultrafast laser pulse using a phase mask approach. The fiber Bragg gratings tests were carried out in the core region of a 6 MW MIT research reactor (MITR) at a steady temperature above 600°C and an average fast neutron (>1 MeV) flux >1.2 × 10 n/cm/s. Fifty five-day tests of FBG sensors showed less than 5 dB reduction in FBG peak strength after over 1 × 10 n/cm of accumulated fast neutron dose. The radiation-induced compaction of FBG sensors produced less than 5.5 nm FBG wavelength shift toward shorter wavelength. To test temporal responses of FBG sensors, a number of reactor anomaly events were artificially created to abruptly change reactor power, temperature, and neutron flux over short periods of time. The thermal sensitivity and temporal responses of FBGs were determined at different accumulated doses of neutron flux. Results presented in this paper reveal that temperature-stable Type-II FBGs fabricated in radiation-hardened fibers can survive harsh in-pile conditions. Despite large parameter drift induced by strong nuclear radiation, further engineering and innovation on both optical fibers and fiber devices could lead to useful fiber sensors for various in-pile measurements to improve safety and efficiency of existing and next generation nuclear reactors.
Several programs funded by the Department of Energy Office of Nuclear Energy (DOE-NE), such as the Fuel Cycle Research and Development, Advanced Reactor Concepts, Light Water Reactor Sustainability, and Next Generation Nuclear Plant programs, are investigating new fuels and materials for advanced and existing reactors. A key objective of such programs is to understand the performance of these fuels and materials during irradiation. The Nuclear Energy Enabling Technology (NEET) Advanced Sensors and Instrumentation (ASI) in-pile instrumentation development activities are focused upon addressing cross-cutting needs for DOE-NE irradiation testing by providing higher fidelity, real-time data, with increased accuracy and resolution from smaller, compact sensors that are less intrusive.Ultrasonic technologies offer the potential to measure a range of parameters during irradiation of fuels and materials, including geometry changes, temperature, crack initiation and growth, gas pressure and composition, and microstructural changes under harsh irradiation test conditions. There are two primary issues that currently limit in-pile deployment of ultrasonic sensors. The first is transducer survivability. The ability of ultrasonic transducer materials to maintain their useful properties during an irradiation must be demonstrated. The second issue is signal processing. Ultrasonic testing is typically performed in a lab or field environment, where the sensor and sample are accessible. The harsh nature of in-pile testing and the variety of desired measurements demand that an enhanced signal processing capability be developed to make in-pile ultrasonic sensors viable. To address these issues, the NEET ASI program funded a three year Ultrasonic Transducer Irradiation and Signal Processing Enhancements project, which was completed as a collaborative effort between the
Abstract. As part of the Advanced Test Reactor National Scientific User Facility (ATR-NSUF) program, the Idaho National Laboratory (INL) has developed in-house capabilities to fabricate, test, and qualify new and enhanced temperature sensors for irradiation testing. Clearly, temperature sensor selection for irradiation tests will be determined based on the irradiation environment and budget. However, temperature sensors now offered by INL include a wide array of melt wires in small capsules, silicon carbide monitors, commercially available thermocouples, and specialized high temperature irradiation resistant thermocouples containing doped molybdenum and niobium alloy thermoelements. In addition, efforts have been initiated to develop and evaluate ultrasonic thermometers for irradiation testing. This array of temperature monitoring options now available to ATR and other Material and Test Reactor (MTR) users fulfills recent customer requests.
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