It's taking more than hammers and cement mixers to build the Hanford vitrification plant. Workers also are using high-tech construction tools that rely on ultrasound and lasers.
Invention was a necessity.
Faced with the need to install more than 193 miles of piping at Hanford's vitrification plant, Bechtel National had to come up with new construction technologies to do the work more efficiently.
"Just the scale of the project has driven it," said Ty Troutman, Bechtel manager of construction for the plant. "There was no technology that can get this done in the time frame we have. What's there won't work for us."
The massive $12.2 billion plant must be ready in 2019 to turn much of 56 million gallons of radioactive waste left from the nation's nuclear weapons program into a stable glass form for disposal.
Workers needed more efficient ways to check welds to nuclear standards, plan complex piping installations and make sure piping modules would attach precisely to other piping within the plant.
The solutions they came up with are, in some cases, already being used on construction projects elsewhere.
That includes a new safer and more efficient way of checking welds to ensure they meet the high standards required for a nuclear processing plant.
Thousands of welds are needed on the more than 1 million linear feet of pipe being assembled and installed in the plant. For piping that will carry radioactive waste, weld inspections are required to show the details of the weld all the way through.
Traditionally that has been done with an X-ray, which requires that work be disrupted to set up an exclusion zone to protect other workers in the area from radiation.
Ultrasonic imaging, which doesn't have the risk of radiation, has been used in the construction industry, but typically for steel structures like buildings. Until advances at the vitrification plant, there was no way to do a volumetric inspection of a pipe weld with ultrasound.
The challenge over the years has been how to go around the pipe, Troutman said. X-ray was the only sure way to make sure the entire weld was examined.
Bechtel solved that by coupling automatic welding technology with an ultrasonic transponder, allowing the ultrasonic transponder to travel in a prescribed path around the pipe on a carriage usually used for automatic welding.
"We took what for years had been a static technology ... and made it dynamic," Troutman said.
It not only is safer for workers, but also more convenient. It can be done in tight spaces and without nearby piping interfering with the image. And just as digital cameras do away with film that has to be developed and stored, Automated Ultrasonic Testing creates an image on a computer in real time.
"It is a technology born out of need here, but transplantable to any process piping," Troutman said. It's already being used elsewhere in the oil, gas, chemical and power industries, he said.
Improvements in computer modeling of piping also were made with the marriage of technology already available separately.
"It was again driven out of need and complexity," Troutman said.
Three-dimensional modeling software has traditionally be used to plan construction jobs and track their progress. But Bechtel has expanded its use for day-to-day work planning.
"Because of the complexity and density of the piping, it becomes very easy to work yourself into a hole.," he said. "It has some of the highest density of any project I've seen in the world."
The new software combines information on project design with the fabrication delivery schedule of piping, to produce a color-coded model that workers can check to instantly see the status of each pipe.
Engineers in the field and other workers can peel back spaghetti-like mazes of piping on a computer screen to get to the place area are working on. They can see what piping has been installed and what piping has been fabricated and is ready to install to correctly sequence the work.
"It really is an amazing tool at the worker level," Troutman said. "It's a view of the world they have never been able to see."
Bechtel is starting to transfer it to its other projects, including power projects and chemical weapon demolition projects.
For safety, many of the complex piping modules are built on the ground and then lifted into place at higher elevations in vitrification plant buildings.
"We want to know that every single connection lines up," Troutman said. A module can have several thousand connections.
That could be done by surveying, but the process would take days and be less accurate. Instead, Bechtel is building laser maps of each module, creating millions of data points for a three-dimensional image of the location of everything on the module.
That allows a check to be done to make sure all the pipes line up before the module is placed, Troutman said.
The first piping module was lifted over the 98-foot-tall walls of the Pretreatment Facility and fitted into place just months ago. Work started with the smallest module, but it still weighed 19 tons and had 3,900 linear feet of nuclear-quality piping ranging in size from 0.5 to 26 inches in diameter.
Only one connection had to be moved after the first module was placed, and that was known in advance, Troutman said.
Laser mapping technology is not new, but Bechtel officials said this is one of its most complex uses, showing promise to cut down rework at the construction project.