Droplet/particle sizing systems used for heat transfer measurements and simulation of loss-of-cooling incident in a pressurised nuclear reactor
When Penn State University's department of mechanical and nuclear engineering was studying what might happen in a loss-of-coolant accident in a pressurised nuclear reactor, it used an Oxford Lasers VisiSizer system to find the answer.
Penn State researchers taking part in the Nuclear Regulatory Commission's 'Rod Bundle Heat Transfer' programme decided to simulate a loss-of-coolant accident when the core of the reactor was re-flooded following coolant expulsion.
As the water level rose, water droplets were created by contact with fuel rods now at elevated temperatures.
Droplets entrained in steam rising from the surface of the water helped to cool the exposed portions of the rods but the cooling efficiency of these droplets was a significant part of the study.
Very fast re-flooding made it almost impossible to capture images or data. As well as being capable of very high speeds, the measurement system chosen had to be non-invasive and able to operate using the small quartz viewing windows already designed for the RBHT housing.
An Oxford Lasers VisiSizer was selected.
It was able to measure droplet population size and velocity distributions simultaneously, allowing researchers for the first time to make accurate predictions of heat transfer and set safety standards. Better understanding of safety parameters indicated that a 1% increase in power output would be possible in pressurised water nuclear reactors.
The technique works by capturing images of droplets or particles using high resolution cameras together with short pulse laser illumination to freeze the motion.
VisiSize Solo Software then measures the particle size and shape and calculates the size distribution.
Size and shape measurement of a wide range of solid particles, powders, liquid drops/droplets, gas bubbles, bubbly flows, bubbles in chemical reactors etc can be performed by Oxford Lasers range of VisiSizer systems.
No other diagnostic tool is as intuitive to use as direct imaging equipment - if you can operate a camcorder or digital camera, you can master a VisiSizer analyser, says the company.
VisiSizer not only provides accurate particle size distributions but also records images of the subject (particle/drop/droplet/bubble). This gives VisiSizer the unique ability to generate particle sizing, drop sizing, (such as spray nozzle droplets), bubble sizing and velocity measurements and images of the particles/drops/droplets/bubbles simultaneously.
