SUCCESSFUL DEPLOYMENT OF THE SCARAB III REMOTELY OPERATED VEHICLE FOR COLLECTION OF SLUDGE SAMPLE FROM UNDERGROUND RADIOACTIVE WASTE STORAGE TANK

In May 1999, the Scarab III remotely operated vehicle was successfully utilized to retrieve sludge samples from numerous locations within Tank T-14, an inactive underground radioactive waste storage tank at Oak Ridge National Laboratory (ORNL). This activity completed the first deployment of the Scarab III system in a radiological environment, and resulted in the collection of representative samples of Tank T-14. The Scarab III system was developed under the auspices of the Department of Energy (DOE) Office of Science and Technology (OST) and the Robotics Crosscutting Program in coordination with the Tanks Focus Area. Deployment was performed as a joint project funded by the ORNL Environmental Restoration Program and DOE OST Accelerated Site Technology Deployment (ASTD) Program. This system is a robotic operating platform originally developed by ROV Technologies, Inc. to perform inspection, sampling, and clean out of reactor pools. The system was modified for inspection/sampling of underground tanks with small accesses containing several inches of sludge across the DOE complex. The key modifications included use of stainless steel construction for corrosion prevention, higher capacity drive motors to compensate for the increased weight of stainless steel, chassis sized for 45.7-cm (18-in) diameter riser openings, rubber-treaded metal tracks for improved traction, and several control system modifications. The ORNL Robotics and Process Systems Division (RPSD) designed and provided oversight for fabrication of a deployment and containment module (DCM) to support the deployment of the Scarab III remote system. The DCM provides storage, containment, interface with tank, glove ports, bag-in/bag-out ports, transfer chamber, and decontamination capabilities. In addition, the Scarab III requires a control console for vehicle operation and video/photo documentation. The Scarab III system was integrated with the DCM and tested at the ORNL Tank Technology Cold Test Facility (TTCTF) prior to deployment in a radiologically contaminated tank. After successful integration and operation at the TTCTF, the Scarab III system was deployed in Tank T-14 satisfying all objectives of the sampling campaign. Observations indicated that the vehicle could operate effectively in radioactive sludge up to about 20.3 cm (8 in) in depth. Operating time for retrieval of the required nine waste samples was 7.6 hours. Many of the techniques developed and practiced extensively during cold testing proved quite valuable during the Tank T-14 sample collection activities and ensured a smooth and successful campaign. Videotape records were created and are available for essentially all in-tank activities. The system has since been demobilized and placed in storage at ORNL awaiting future deployment opportunities.