Engineers from Lancaster University, the National Physical Laboratory, and Hybrid Instruments Ltd, inspired by bats' echolocation, have developed a new scanning technique to detect corroding metals in oil and gas pipelines. The technique mimics the different ultrasonic wavelengths used in echolocation in a system which combines two separate types of radiation: fast neutrons and gamma rays. The radiation works together to detect corrosion, which is a major cause of pipeline leaks.
This new technique was developed specifically for underground pipelines and those covered with insulating layers of concrete or plastic, as traditional electromagnetic techniques aren't effective enough. With endless miles of pipes transporting endless gallons of gas and oil around the world, a leak could cost millions, not to mention cause harm to workers and the environment, and so it's crucial they're detected and taken care of as quickly as possible.
Two Types of Radiation
Before they are slowed down by a large number of nuclear collisions, neutrons produced by fission reactions are considered fast, according to Radioactivity EU. They can be used in fast neutron reactors as a source of clean energy, but much research is still being done on the subject. Fast neutrons interact mainly with low density materials, like plastics.
Gamma rays are the highest energy electromagnetic radiation. They are sometimes used in radiation therapy to treat cancer, and are also heavily studied in astronomy, according to Live Science. Gamma rays interact mainly with metals.
The New System
The new system exploits the reflected back scatter of isolated fast-neutron and gamma radiation. According to Phys Org, fast neutrons have a high-penetrating power and are suitable for probing thick materials, while gamma rays interact mainly with metals and are not always able to penetrate materials of high density. When the two rays are measured together, however, they produce a different electronic signal. Phys Org says this signal can be detected using a Mixed Field Analyser, which was developed by Lancaster University and Hybrid Instruments Ltd previously. The new system shoots a beam of fast neutrons and gamma radiation at the metal to inspect for corrosion.
The team of developing engineers tested the two imaging techniques in real time in a laboratory on samples of carbon-steel of different thicknesses, and were able to see significant differences, meaning the device and system were functional as intended. The sensors were also successful when used through an insulating layer of concrete or plastic in order to simulate the surroundings of many actual gas and oil pipelines. This means the system could be used on actual pipelines to detect potential issues early on, likely before gas or oil is even able to escape.
Inspired by Echolocation
Mauro Licata, a Ph.D. researcher from Lancaster University, explained how the system was inspired. "The combined beams of neutrons and gamma rays in parallel bouncing back to an array of detectors yield a comprehensive and fast representation of the inner structure of steel. This system works a bit like the chirps made by bats," he said. "These chirps are a superposition of different ultrasound wavelengths, which bounce back to the bats' ears. As well as highlighting the benefits of combining multiple reflection sensing techniques to detect problems such as corrosion, our work further illustrates the significant potential that can be had from taking inspiration from, and mimicking, systems that have evolved in the natural world."
Further directions this technology could be taken in include inspecting the integrity of other large scale buildings and structures. Although the possibilities appear to be endless, the developers emphasized that more research in the field of neutron detectors is crucial to making their system more efficient.