After the Daiichi nuclear disaster, the US Congress placed emphasis on accident tolerant fuels for reactors. During accident events, voids in cooling fluid can cause cladding weakening, and it is important to measure these effects in a controlled test.The project develops a fast void detector that can detect and localize voids, with a quantifiable detection limit superior to a capacitive void sensor. The project uses modeling and simulation of the RF sensor and environment, designs RF elements for the harsh environment, and fabricates the devices for temperature and pressure requirements. During Phase I, the effort performed theoretical work to simulate performance. Second, the effort refined the RF sensor designs. Third, the effort fabricated devices. Fourth, the effort demonstrated feasibility with a demonstration of the technology. First, the effort performs theoretical work required to form numerical models and simulations of performance. Second, the effort brings into service an autoclave to produce the temperatures and pressures needed. Third, the project develops the component and sensors to prepare for commercial application. Fifth, the effort develops the software for void sensing and bubble size characterization and migrates experimental software set to a commercialized product. Finally, the project completes by validating the system through a design of experiments and system testing. The proposed effort is a critical part of fuel technology optimization for LWR. The benefits include improved: fuel safety, LWR fuel burnup, and accident tolerance. Understanding void formation will help determine new reactor type fuel safety criteria. The new reactors have applicability for commercial power production, science experimentation (e.g., neutron science), and space propulsion.
