The U.S. Department of Energy's Office of Science and Technology has successfully dovetailed several of its technologies, demonstrating how they can be used together for remote retrieval of radioactive liquid and sludge from underground storage tanks. During December and January, Oak Ridge National Laboratory hosted open-house demonstrations of three remotely operated technologies: the Modified Light Duty Utility Arm, Houdini, and a waste dislodging and conveyance system. True to the collaborative nature of this project, the December open house was attended by more than 230 visitors from all over the DOE complex, from the U.S. Environmental Protection Agency and other regulatory bodies, universities, environmental technology manufacturers, remediation contractors, and other stakeholders. January attendees included Congressman Zachary Wamp from Tennessee, and Clyde Frank, OST's deputy assistant secretary. OST's tanks focus area decided in May 1994 to combine and modify mature and emerging technologies to optimize its technology investment in tank characterization and retrieval. Previous attempts to sluice (suspend waste in a removable liquid) the contents of gunite and associated tanks at ORNL during the 1980s removed about 500,000 gallons of waste, leaving 350,000 gallons of liquid and 50,000 gallons of sludge. The use of an integrated retrieval system will tackle the remaining liquid and sludge, dropping the projected cost to remediate ORNL tanks from $400 million to $74 million. By meshing technologies from various private and national laboratories, OST has achieved an integrated system that tackles the challenges posed by ORNL's gunite and associated tanks better than any of the retrieval systems could have done working alone. Similar systems may also be applicable to other DOE tanks at the Hanford Site in Washington state, the Savannah River Site in South Carolina, the Fernald Site in Ohio, and the Idaho National Engineering and Environmental Laboratory. These tanks--many of which are beginning to deteriorate--store radioactive and chemical byproducts of weapons research and production. Major collaborators in this project include six national labs, four universities, several management and operations contractors, and more than 15 private companies from all over the United States and Canada. By working closely with site managers, the demonstration team has ensured that system designs will adequately meet retrieval requirements. ORNL proudly describes this widespread collaboration as one of the major reasons for the project's timeliness and success. Modified Light Duty Utility Arm The MLDUA is the newest version of the OST-funded LDUAs built by Spar Aerospace of Toronto. The original LDUA, deployed at Hanford in September 1996, is truck mounted and carries a payload of 75 pounds. Spar modified the arm to meet ORNL specifications: the MLDUA can fit through 12-inch-diameter risers and lift 200 pound payloads, all from a skid-mounted base. The MLDUA can reach 50 feet down and 15 feet horizontally with eight degrees of freedom. A tool interface at the end of the arm provides utilities and communications to end effectors, including sluicers and characterization equipment. To access an entire 50-foot-diameter tank, the MLDUA would need to be inserted at four separate ports. Encased in confinement housing, the MLDUA withstands radioactive and low-pH environments. Housing pressurization deters contaminants from entering the arm. The system also features a tank riser interface and containment box, allowing operators to attach end effectors using glove ports and to decontaminate the unit using a spray ring and wand. Operators control the MLDUA from a trailer up to 900 feet away, reviewing input from a workstation. They can either manipulate the MLDUA using joysticks and other controls or program the arm for automated operation. Four LDUAs have already been delivered or scheduled for deployment: the first went to Hanford in April 1996; and the second, the modified arm, went to ORNL in November. The third arm, built to the original LDUA specifications, is due this spring at Hanford. And the fourth, due this spring at INEEL, will be skid mounted like the ORNL version. Houdini Houdini is aptly named for its ability to get in and out of tight spaces--24-inch tank risers, to be precise. It unfolds into a hydraulically powered combination bulldozer and backhoe with a footprint of roughly 4 feet square. The 1,000-pound, tethered vehicle moves on continuous tracks with rugged tread. Its Schilling Titan manipulator arm has six degrees of freedom, a six-foot reach, and a 240-pound payload. The arm can carry specialized end effectors, such as the sluicer described below. Houdini can deliver roughly 650 pounds of plowing force, pushing sludge to a removal hose or auger. Much like the MLDUA, Houdini can be cleaned, inspected, and modified above ground through a casing equipped with view panels and glove boxes. Operators control the initial deployment from the Power Distribution and Control Unit, located up to 75 feet from the tank. In subsequent operations, workers can control Houdini from another 300 feet away in a room housing four camera monitors for teleoperation, joystick and foot-pedal controls, and other instrumentation. Houdini's initial development by RedZone Robotics was funded by OST through the Morgantown Office of the Federal Energy Technology Center. After testing a Houdini prototype for use in Fernald silos, the Robotics Technology Development Program decided to reroute and slightly reconfigure the first complete Houdini system for its current testing and use at Oak Ridge. As a result, Fernald should have a second-generation Houdini late this year, modified based on ORNL hot tests. Brack Hazen, senior robotics engineer at Fluor Daniel Fernald, was happy to be preempted: "We are thrilled to death that Oak Ridge has been the guinea pig for us. Our retrieval will be much longer and involve more material than Oak Ridge's. By watching their demonstration, we were able to capture reams of information in terms of lessons learned." He was also glad for the opportunity to take his operators to the open house to gain some field experience with the systems: "We got to kick the tires and test drive the whole system." Waste dislodging and conveyance Waste dislodging and conveyance was performed by a Confined Sluicing End Effector mounted on a Hose Management Arm. ORNL and Pacific Northwest National Laboratory worked with private contractors to tackle this prolonged remediation task. Waterjet Technologies built the CSEE, and Advanced Systems Technologies collaborated with ORNL to design the HMA, which was built by Tennessee Tool and Engineering. The CSEE consists of three rotating jets that pump 10 gallons of water per minute at up to 10,000 psi on four- to six-inch-wide target areas. The waste conveyance line suctions slurries of dislodged waste from 25 horizontal feet away and up 50 vertical feet, drawing the waste to aboveground storage. The 45-pound CSEE has two grasping handles designed for deployment on either Houdini or the MLDUA. The Hose Management Arm bears much of the weight of and acts as a pipeline for the CSEE. The HMA and CSEE have a combined horizontal reach of 25 feet, allowing them to access an entire 50-foot diameter tank, as found in the gunite and associated tank farm at ORNL. As they leave a contaminated tank, the CSEE and HMA are sprayed with water at 2,100 psi and then drawn into a containment box. Glove ports allow access for further decontamination and maintenance. The entire system, including flow control equipment, is operated remotely and may eventually be automated. ORNL has ordered a higher- pressure CSEE from Waterjet. The 30,000-psi CSEE unit will increase the gunite scarification depth capability from 0.1 inches to the desired 0.25 inches. By using the Houdini and MLDUA simultaneously, ORNL investigators will be able to aim the higher-pressure CSEE on the walls, while using the 10,000-psi CSEE on sludge. Integrated versus solo deployment Barry Burks, who coordinated the entire ORNL demonstration, expressed his satisfaction with both the arm and vehicle retrieval systems. "ORNL is committed to using both systems in its hot tanks. I think you'll find other sites giving this integrated system serious consideration, especially for retrieving complex waste forms." Speaking from field experience with both systems, Burks was able to describe the unique strengths of the two systems. For example, Burks described the Houdini vehicle as "fast and efficient at grabbing objects." Moving around the tanks at 1.2 feet per second, Houdini can pick up large clumps weighing up to 250 pounds. In contrast, "The MLDUA effectively has a much smaller payload for retrieving, since its grabber end effector weighs 60 pounds, reducing the effective payload to 140 pounds." (Houdini's grabbing arm is pre-installed.) The MLDUA also moves much more slowly--roughly five inches per second. While the MLDUA operates above the waste surface and is doubly encased against contamination, Houdini sits on or in the sludge. "Houdini has lots of crevices and exposed cables that collect sludge and require extra downtime for manual decontamination through glove boxes," Burks explained. Another obvious difference between the two is their mode of operation: teleoperated versus automatable. Houdini is fully teleoperated--operators rely on cameras to guide them in steering the vehicle. In contrast, "MLDUA operators always know the exact position of the arm," said Burks, "since each joint has a position encoder." Lee Maher of SPAR explained that these position devices "allow operators to encode any trajectory they want. For example, the arm can be programmed to follow the inner curvature of the tank in an auto-mated, controlled mining-type sweep. Alternately, operators can perform a task and have the arm "learn" to duplicate the task on command. According to Burks, the individual characteristics of each system make them a perfect team for complex waste retrieval: "I think this combined demonstration really turned a lot of heads. Site managers seem to be realizing the benefits of integrated deployment of these two systems." Fernald's Hazen confirmed this supposition: "Site managers here have always focused on using Houdini; but after seeing the two working together, they are giving some consideration to using both Houdini and the MLDUA." Further information Complete details on the ORNL demonstration may be found in an article by B.L. Burks et al. that appeared in the March 1997 Radwaste Magazine. Burks may reached at (423) 576-7350 or burksbl@ornl.gov. For more information on the MLDUA, contact Lee Maher of SPAR Aerospace Ltd. at (905) 760-4414 or lmaher@spar.com. Regarding the Houdini system, contact Tim Denmeade of RedZone Robotics at (412) 765-3064 or tdenmeade@redzone.com. And for details on the CSEE, call Dan Alberts of Waterjet Technologies at (206) 872-1366 or dama@qi2.com.