Advanced Laser Ultrasonic Sensor for Fuel Rod Characterization

Advanced sensors and instrumentation are required to extend the life of current nuclear power reactors, and for use in the family of next generation reactors. Such sensors must operate effectively in cooling pools and eventually in the harsh reactor environment. Current fuelrod sensors suffer from one or more of the following critical disadvantages: low reliability, requiring disassembly of the fuel rod array, requiring slow procedures, and/or inability to measure pressure increase above nominal. Laser ultrasonic testing will be applied to meet the requirements for inpool and inreactor measurements of fuelrod pressure and cladding wall thickness. In Phase I the feasibility of applying laser ultrasonic testing for noncontact measurements of the internal pressure in nuclear fuel rods, as well as strain and cladding wall thickness, was demonstrated. This feasibility was shown for both measurements conducted in air and under water, such as in a cooling pool. The sensitivity of the measurement technique, combined with novel signalprocessing algorithms, enables detection of either overpressure or underpressure conditions. A prototype measurement system to be tested in a simulated storage pool environment will be developed. Specifications will be prepared for a radiation and temperaturehardened system to be demonstrated in a utility cooling pool during a followon Phase II effort. The end users of products developed in this project are the nuclear power utilities, and laboratories with test reactors. There is also potential for use in the International Nuclear Fusion Research and Engineering project fusion reactor and future fusion power reactors. Dualuse commercial markets include conventional coalfired or gasfired power utilities. This project will advance the Department of Energy Nuclear Sciences mission by contributing to the scientific foundation for life extension of current nuclear power plants and improved instrumentation for more efficient functioning of the next generation of power plant designs. It addresses the need for improved harsh environment sensors. Beyond the monitoring of fuel rods, the sensor is expected to also find application in monitoring other reactor components such as the containment vessel and cooling components. Use of the sensor will benefit the commercial plant operators and the manufacturers of plant components, particularly fuel rods. The public will benefit from reduced power costs and from safer, more reliable, and sustaining power generation.