ORNL has unique capabilities in the development and implementation of technologies for measuring, monitoring, and controlling a variety of systems. We apply our expertise and instrumentation in electronics, photonics, imaging, and signal processing to biological, chemical, and nuclear concerns. Our goals are improved environmental quality and health protection as well as more accurate data to support science missions. The capabilities represented by this competency span the range from basic research in materials and processes through prototype development to production-scale facilities for precision manufacturing and inspection.
ORNL and Oak Ridge Y-12 Plant user facilities that promote the development of these technologies are the Metrology Research and Development Laboratories, the Metals Processing Laboratory User (MPLUS) Center, and the Oak Ridge Centers for Manufacturing Technology. With all these capabilities, we measure up to most peoples expectations.
Helping U.S.Textile Firms Weave Quality Fabric
ORNLs Jack LaForge is a member of a team that seeks to make the U.S. textile industry more competitive worldwide. ORNL and five other DOE laboratories contribute to the Computer-Aided Fabric Evaluation project, which incorporates on-line fabric inspection into weaving looms to dramatically increase the quality of U.S.-produced fabric. Photograph by Bill Norris.
Faced with looming job losses because of stiff foreign competition, the U.S. textile industry is weaving new technology into its strategy to regain the competitive edge. Heres the problem. Since 1980 the U.S. textile industry has lost businessand 400,000 jobsto foreign textile companies because of its higher labor costs; if the trend continues, another 600,000 jobs could be lost by 2002 in an industry that produces not only clothing but also carpeting, medical dressings, and automotive airbags. Heres a possible solution. The domestic textile industry can compete more effectively if it finds an economical way to produce visually flawless fabrics of a quality high enough that consumers will buy them in large quantities. To improve weaving technology to increase demand for its textiles, the U.S. industry has been collaborating with Department of Energy laboratories (including ORNL) in the Computer-Aided Fabric Evaluation (CAFE) Project.
Todays textile mills use high-speed looms to weave yarn into cloth. Inspectors in the mill manually feel and visually examine the cloth, looking for defects. Sometimes they miss the less obvious ones, and defective material passes through the entire textile system, eventually reaching the marketplace where retailers and consumers notice the flaws and the material is marked down or returned as a loss.
One strategy for stemming such financial losses is to develop a technology to inspect fabric while it is being woven. During the weaving process, horizontal filling, or pick, yarn is laid down at a right angle to the warp yarns that run lengthwise through the fabric. Fabric quality and the amount of yarn used, both of which can affect product cost, strongly depend on the regularity and density of the pick yarn (strands per inch). Thus, the CAFE project called for the development of a user-friendly inspection of defect detection system for industrial looms that measures pick density and locates flaws in fabric in real time. This system should help textile mills and apparel manufacturers minimize their production of reduced-price, second-grade merchandise and bad cloth that must be discarded, cutting their financial losses and saving jobs.
ORNL and Oak Ridge Y-12 Plant researchers have invented an optical device that meets the CAFE criteria. The new linear diode pick measurement device, which is cheaper than conventional camera systems and easily installed on existing looms, images and inspects textiles on the loom in real time. Using this simple and reliable combination of lasers, diodes, and lenses linked to a computer, loom operators can measure pick density and variability, map defects electronically, and identify fabric anomalies as the fabric is woven. From this real-time information, operators will instantly correct loom operation to halt production of defects and tag defective material for rejectionwithout stopping the loom. Tests of the on-line sensor system began at three U.S. textile mills in July 1996 and continue to run through 1997. Operation of the high-tech weaving systems was successful. Technology may save the day for U.S. textiles.
Funding for this development came from DOEs Defense programs, Office of Technology Partnerships.
Heartbeat Detector Senses Persons Hiding in Vehicles
The heartbeat detector can detect a prisoner or intruder hidden in a truck. Drawing by Reneé Balogh.
An 18-wheeler pulls into the portal of a nuclear defense plant to deliver heavy equipment, The guard says to the driver, Please turn off your engine and everybody get out of the truck for a few minutes. A man and woman step out. The guards next task is to search every nook and cranny, every box and package, in the truck. The object of the time-consuming search is a hidden armed terrorist bent on holding the plants personnel hostage.
That was the old way. Now, the guard attaches six vibration sensors to the outside of the truck. These sensors are linked by cables to a signal-amplifying box attached to a sturdy laptop PC. The guard hits a function key on the laptop keyboard and watches signals ripple across the computer screen. In 20 seconds, a green rectangular flag appears at the top right of the screen. The message at the bottom of the screen says, No intruder detected. PASS. But had the flag come up red, the message would have read, INTRUDER DETECTED!! SEARCH.
In the early 1990s, the Department of Energy, concerned that terrorists concealed in vehicles could be sneaked into its defense installation (such as the Oak Ridge Y-12 Plant), called for the design and construction of smart portals. Two Y-12 researchers began work to develop a heartbeat detector to find hidden intruders after learning that in 1991, researchers at Michigan State University had developed a microwave sensor to detect heartbeats at a distance. The Y-12 approach was to detect the telltale heartbeat using vibration sensors and a laptop computer to tease out the heartbeat signal from the trucks other vibrations induced by natural resonances, wind, and other influences.
Such an enclosed space detection system, popularly known as the heartbeat detector, has been built and installed at Y-12s portal of the future, which will also incorporate undervehicle surveillance cameras, fiber-optic weigh-in-motion technology, and detectors of special nuclear materials and explosives. Portals of the future will economically reduce the time needed to inspect each vehicle while increasing the level of security. In fact, the heartbeat detector is 10 to 250 times faster than human inspection, and its cost is only 3% that of conventional methods.
As the heart uses energy to pump blood, its regular, vigorous pulsations send shock waves through the body. The energy of the bodys vibrations is transferred to any object the body touches, such as the inside of a truck. Amazingly, a hidden persons heart transmits pulsating energy that can be detected at the trucks exterior surface by vibration sensors linked to a computer.
To make it possible to detect the presence or absence of a heartbeat among the trucks other vibrations, ORNL researchers were asked to develop a mathematical procedure called an algorithm. The algorithm they developed uses a mathematical function called a waveleta small wave that rapidly dies out. The wavelets in the algorithm have a characteristic shape that closely matches typical human heartbeat signals. Using the wavelet function algorithm, the computer compares the wavelet functions to vibration signals from the truck. If theres a close match, the computer tells the guard to search the truck; if theres no match, the guard gets the green light and lets the truck pass through the portal without a search.
The heartbeat detector has other obvious applications. For example, it could detect any prisoner who tries to escape by hiding in a laundry truck. It could pinpoint illegal aliens from Mexico who sometimes sneak across the border to the United States in cars after taking the stuffing out of car seats and squeezing in under them. In 1996 the heartbeat detector was tested at two prisons: the Riverbend Maximum Security Institution in Nashville, Tennessee, and the Centinela State Prison in California. It was also tested for eight hours each at the San Ysidro and Otay Mesa portals at two border crossings between Mexico and the United States.
Because of its practical uses, the Oak Ridge heartbeat detector was licensed by Lockheed Martin Energy Systems to Geovox Security, Inc., which introduced a commercial version in the fall of 1996. The company has sold one heartbeat detector to the British Home Office (equivalent of the U.S. departments of Justice and the Interior), which operates all United Kingdom prisons. Many U.S. prison facilities are interested in purchasing heartbeat detectors, as well. They want to guard against letting the wrong people out just as DOEs nuclear defense plants want to guard against letting the wrong people in.
The project was funded by DOEs Office of Security Affairs.
ORNL Devises Way To Prevent Steam Explosions
|Schematic of the SETS facility. Inside a steel crucible a pool of molten aluminum is supported by a tungsten plate that lets heat pass through it back and forth almost as fast as the molten aluminum would. However, tungsten melts at a much higher temperature. Therefore, accurate, instrumented, quick-turnaround, and safe lab-scale simulations of large and small amounts of aluminum pouring over submerged surfaces become possible. The plate is heated by a radiant heater. The energy of the molten aluminum is transferred through the plate to the entrapped water when the crucible is lowered toward the tank of water. A pneumatic impact hammer is used for some experiments to simulate an external shock. Coated samples (steel disks coated with epoxies, absorbent paper, lubricants, etc.) or uncoated samples (e.g., rusted steel or concrete disks) are mounted at the base of the tank for testing. Variations of back pressure and diameters of heater and base surfaces permit simulations of small- to large-scale events. The instruments detect early pressure pulses and heat transfer phenomena that would eventually trigger a steam explosion, but an actual explosion is avoided in this apparatus.|
In the metal casting industry worldwide, workers have been killed and large buildings and heavy equipment have been destroyed by steam explosions caused by contact of molten metal with water. According to data collected by the Aluminum Association, from 1980 through 1995 the aluminum industry experienced several hundred explosions during casting operations which resulted in hundreds of injuries, about 10 deaths, and extensive property damage. Three devastating explosions occurred in 1986 alone. The steel, magnesium, and pulp and paper industries also encounter steam explosion events. The most famous metal-water explosion of 1986, however, occurred not in these industries but at the Chernobyl nuclear power plant, causing an uncontrollable release of radioactivity over much of Europe.
The aluminum industry, which began conducting its own explosion experiments 40 years ago, concluded that, under certain conditions, a few organic coatings prevent explosions at surfaces submerged in water; however, there was no understanding of why or to what extent the coatings provided protection. The most widely used organic coating in aluminum casting pits is the coal-tar epoxy Tarset Standard. But when this industry mainstay and other similar paints were banned largely because of their toxicity, the industry turned to ORNL for help.
We were asked to conduct basic research to determine why, under what conditions, and to what extent these organic coatings prevent explosions. We were also asked to use this information to devise an alternative, environmentally friendly protective measure. ORNL was chosen because our researchers have been studying the potential problem of steam explosions in water-cooled research reactors in which fuel elements are made of uranium-aluminum mixtures sandwiched between aluminum plates.
In the aluminum industry, an aluminum ingot is formed by pouring molten aluminum into a steel mold that is lowered into a steel-lined (or concrete) pit of water. The water cools the mold, eventually solidifying the aluminum. Because of the chaotic nature of the process, significant quantities of molten aluminum can pour over submerged surfaces, sometimes leading to energetic explosions. To reduce the chance of a catastrophic event, the aluminum industry has coated the mold and pit linings with organic coatings such as Tarset Standard.
When molten aluminum first comes into contact with water, a protective steam film forms. It has been found that some sort of trigger causes the steam film to destabilize and collapse. As a result, the molten aluminum mass breaks into literally millions of hot particles, causing water they come in contact with to flash to high-pressure steam. ORNL researchers proposed that explosive boiling of entrapped water and external shocks (e.g., from jack hammers used in metal casting houses) could serve as triggers. ORNL researchers also suggested that noncondensible gases introduced into the steam film would cushion external triggers.
To test these ideas and find out why some coatings are more effective than others in preventing steam explosions, we developed a unique experimental apparatus called the Steam Explosion Triggering Studies (SETS) facility. In this facility, molten aluminum never comes in contact with water in a tank so there is no danger of a steam explosion. However, the facility can accurately simulate heat transfer from molten aluminum moving over submerged surfaces.
Tests on the SETS apparatus produced unique insights into the physics of steam explosion triggering. As the coated metal samples heat up, the coatings decompose and char, generating copious quantities of gases that tend to drive entrapped water away. Because there is no significant water to entrap, explosive forces for triggering are eliminated. Further, these gases migrate to the free aluminum surface and absorb external shocks like airbags. The charred areas and the gases generated by heating the coated surfaces repel waterbeads of water easily roll off the samples when you blow them.
On the other hand, our studies of uncoated, rusted steel samples show they are quite wettablewater spreads and coats the steel. Thus, rusted steel traps a mixture of water and steam, making it available for explosive boiling heat transfer, which can send shock waves to trigger a steam explosion. SETS tests demonstrate that the buildup of potentially explosive energy was much greater over rusted steel than over samples with coatings thought to suppress steam explosions. Other tests showed that practically achievable external shocks in casthouses, such as jackhammers or large ingots accidentally dropped onto operating floors, were much less significant as potential triggers than explosive boiling of entrapped water from submerged surfaces.
Based on our studies of explosions and coatings, we postulated that steam explosions could be prevented by injecting air (or some other noncondensible gas) at critical locations and prescribed rates based on process conditions. Lab-scale experiments indicate that gas inclusion in the steam film around molten particles can significantly stabilize the protective steam film and cushion against destabilizing shock pressures. Field demonstrations of our new gas injection technique, which are planned to demonstrate its usefulness to the aluminum industry, will be carried out later this decade by ORNL and the Aluminum Association of America under a cooperative research and development agreement.
ORNL researchers have also suggested that gas injection and special coatings at the bottom of pressure vessels or reactor cavities may prevent steam explosions in DOE research reactors and commercial nuclear power plants. We hope our research results will help improve the safety of the metal casting and nuclear industries.
The research is sponsored by DOEs Office of Energy Research, Laboratory Technology Research Program, and by DOEs Office of Energy Efficiency, Office of Industrial Technologies.
Monitor Warns of Need To Change Oil Drill Bit
David Holcomb (left) and Nance Ericson show where the electronic temperature monitor they developed will fit into an oil drill bit to warn of failure before it actually occurs. Photograph by Tom Cerniglio.
One of the worst nightmares of oil and gas exploration companies is a broken drill bit. Suspended from an oil drilling rig by a string of pipes, this knee-high steel mechanism is the key to striking oil and gas. A succession of drill bits bores through up to 6000 meters (~20,000 feet) of rock with roughly 200,000 newtons (50,000 pounds) of weight on each bit while enduring downhole pressures that can reach 130megapascals (~20,000 pounds per square inch). Operation of a drilling rig can cost as much as $10,000 an hour. If the bit breaks into pieces while drilling on the way down, the cost to a drilling company of the time required to fish the pieces out with a magnet before drilling is resumed could exceed $1 million for a single bit. Thus, to prevent failure, oil drilling companies replace drill bits well before they have reached the end of their useful lives.
Because of the potential to save money, oil drilling companies are interested in a drill bit that could be used much longer. The dream solution: incorporate a device in the bit that warns of telltale changes preceding failure, signaling the need to change out the drill bit just in time. Wide-spread use of such a device would lower the cost of petroleum exploration and production and help ensure that the U.S. market receives oil at a reasonable cost, which is a primary DOE mission.
To meet this need, ORNL, Hughes Christensen Company (a manufacturer of drill bits), and the Houston Advanced Research Center have developed an implantable incipient failure monitor for drill bits through a cooperative research and development agreement. About the size of a small battery, this monitor measures the rise in drill bit temperature, which is an indicator of a number of changes that lead to failure. When drill bits mechanically degrade (say, when the lubricant seals fail), increased friction results, generating heat. So a miniaturized, ruggedized temperature measurement and logging instrument was devised to measure temperatures in the drill bit. This temperature monitor is the first electronic device ever to be incorporated directly into an oil well drill bit.
ORNL researchers designed an integrated circuit that performs four channels of temperature measurement in oil well drill bits. Electronic file enhanced by Mark Robbins.
The temperature monitor operates on very low power levels supplied by a battery. Its materials and components are tolerant of high temperatures (up to 150°C), vibrations, and mechanical shock. The heart of the device is a customized application-specific integrated circuit (ASIC) designed at ORNL. This ASIC consists of an analog circuit that performs the measurement and a mixed analog-and-digital circuit that controls the system and logs the measurements.
Several temperature sensors, whose resistance varies in a known manner with temperature, are implanted at critical points within the drill bit. Measurements are currently being made in tests downhole to identify signatures of different incipient failures for a database. The recorded measurements are retained in the modules nonvolatile memory, even if the power supply is interrupted. The information will aid the design of a more intelligent sensor module that will recognize specific types of expected impending failures.
Rather than measure electrical resistance directly with thermocouples or other conventional methods that require stable, accurate current and voltage sources, the researchers use a timing method that produces a digital result proportional to temperature even if the voltage supply is unstable. The device relies on an oscillator that generates a stable frequency (like a clock ticking, except there are many more ticks per second). The digital information on the incipient failure will be communicated from the sensor monitor by special signals that travel up the hole to oil rig drill operators .
There are other practical applications for this kind of temperature monitor. The device could be used to warn truck drivers that their brakes are on the brink of overheating. Food processors could use such a rugged temperature monitor to ensure that a large batch of stew is cooked throughout long enough and at the right temperature to sterilize it before canning. Other applications might be remote environmental sensing in the Arctic Ocean, monitoring heat-treatment furnace temperatures, and making temperature measurements on the thermal shields of vehicles re-entering the Earths atmosphere from space.
As they seek to help industry find oil and gas more economically, ORNL researchers are finding ways to make smaller, tougher electronic devices that can help other people, too.
The development was funded by DOEs Office of Energy Research, Hughes Christensen Company, and the Houston Advanced Research Center.